the 7 most useful manganese ore beneficiation methods | fote machinery
The data recorded by Statistics in 2020 shows that although in 2019 manganese ore price fell to the bottom, the price in 2020 still gets increased to 4.5 U.S. dollars per metric ton unit CIF even under the impact of COVID-19. Manganese ore prices are forecast to remain at global prices by 2020 over the next two years, which is good news to manganese ore suppliers.
Besides, Justin Brown, managing director of Element 25said Manganese has the traditional end uses in steel, and that market is fairly stable". As people's demand for laptops and electric cars increases, the output of lithium batteries has also soared, and the most important element in lithium batteries is manganese.
Manganese ore after the beneficiation process is applied in many respects in our daily lives. Of annual manganese ore production, 90 percent is used in steelmaking, and the other 10 percent is used respectively in non-ferrous metallurgy, chemical industry, electronics, battery, agriculture, etc.
In the metallurgical industry, manganese ore is mostly used for manganese-forming ferroalloys and manganese metal. The former is used as deoxidizers or alloying element additives for steelmaking, and the latter is used to smelt certain special alloy steels and non-ferrous metal alloys. Manganese ore can also be used directly as an ingredient in steelmaking and ironmaking.
When smelting manganese-based iron alloys, the useful elements in manganese ore are manganese and iron. The level of manganese is the main indicator for measuring the quality of manganese ore. The iron content is required to have a certain ratio with the amount of manganese.
Phosphorus is the most harmful element in manganese ore. The phosphorus in steel reduces the impact of toughness. Although sulfur is also a harmful element, it has a better desulfurization effect during smelting, and sulfur is volatilized into sulfur dioxide or enters the slag in the form of calcium sulfide or manganese sulfide.
Applications in Metallurgy
Manganese content (%)
Phosphorus manganese (%)
Low carbon ferromanganese
Carbon Ferro Manganese
Manganese Silicon Alloy
Blast Furnace Ferromanganese
In the chemical industry, manganese ore is mainly used to prepare manganese dioxide, manganese sulfate, and potassium permanganate. It is also used to make manganese carbonate, manganese nitrate and manganese chloride.
Since most manganese ore is a fine-grained or fine-grained inlay, and there are a considerable number of high-phosphorus ore, high-iron ore, and symbiotic beneficial metals, it is very difficult to beneficiate.
At present, commonly used manganese ore beneficiation methods include physical beneficiation (washing and screening, gravity separation, strong magnetic separation, flotation separation, joint beneficiation), chemical beneficiation (leaching method) and fire enrichment, etc.
Washing is the use of hydraulic washing or additional mechanical scrubbing to separate the ore from the mud. Commonly used equipment includes washing sieves, cylinder washing machines and trough ore-washing machine.
The washing operation is often accompanied by screening, such as direct flushing on the vibrating screen or sifting the ore (clean ore) obtained by the washing machine to the vibrating screen. Screening is used as an independent operation to separate products of different sizes and grades for various purposes.
At present, the gravity separation is only used to beneficiate manganese ore with simple structure and coarse grain size and is especially suitable for manganese oxide ore with high density. Common methods include heavy media separation, jigging and tabling dressing.
It is essential to recover as much manganese as possible in the gravity concentration zone because its grinding cost is much lower than the manganese in the flotation process, and simple operations are more active.
Because of the simple operation, easy control and strong adaptability of magnetic separation can be used for dressing various manganese ore, and it has dominated the manganese ore dressing in recent years.
Gravity-magnetic separation plant of manganese ore mainly deals with leaching manganese oxide ore, using the jig to treat 30~3 mm of cleaned ore can obtain high-quality manganese-containing more than 40% of manganese. And then can be used as manganese powder of battery raw material.
The jigging tailings and less than 3 mm washed ore are ground to less than 1mm, and then being processed by strong magnetic separator. The manganese concentrate grade would be increased by 24% to 25%, and reaches to 36% to 40%.
Adopting strong magnetic-flotation desulfurization can directly obtain the integrated manganese concentrate product; the use of petroleum sodium sulfonate instead of oxidized paraffin soap as a collector can make the pulp be sorted at neutral and normal temperature, thus saving reagent consumption and energy consumption.
The enrichment of manganese ore by fire is another dressing method for high-phosphorus and high-iron manganese ore which is difficult to select. It is generally called the manganese-rich slag method.
The manganese-rich slag generally contains 35% to 45% Mn, Mn/Fe 12-38, P/Mn<0.002, and is a high-quality raw material to manganese-based alloy. Therefore, fire enrichment is also a promising method for mineral processing for low-manganese with high-phosphorus and high-iron.
Manganese ore also can be recovered by acid leaching for production of battery grade manganese dioxide for low-manganese ores. Leaching of manganese ore was carried out with diluted sulphuric acid in the presence of pyrite in the temperature range from 323 to 363 K.
After processed by hydraulic cone crusher, the smaller-sized manganese ore would be fed to grinding machine- ball mill. It can grind the ore to a relatively fine and uniform particle size, which lays a foundation for further magnetic separation of manganese ore.
It is indispensable grading equipment in the manganese ore beneficiation plant. Because by taking advantage of the natural settling characteristics of ore, a spiral classifier can effectively classify and separate the manganese ore size to help control the amount of grinding required.
The flexibility of flotation is relatively high. You can choose different reagents according to the type and grade of the ore. Although the entire process of froth flotation is expensive, it can extract higher-grade manganese ore.
The magnetic separator is a highly targeted magnetic separation device specially developed for the properties of manganese ore. The device not only has the advantages of small size, lightweight, high automation, simple and reasonable structure, but also has high magnetic separation efficiency and high output.
If you want to beneficiate high-grade manganese ore and maximize the value of manganese concentration, Fote Company is an ore beneficiation equipment manufacturer with more that 35-years designing and manufacturing experience and can give you the most professional advice and offer you all machines needed in the ore beneficiation plant (form crushing stage to ore dressing stage). All machines are tailored to your project requirements.
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us patent for flotation and sintering of synthetic manganese carbonate patent (patent # 4,274,866 issued june 23, 1981) - justia patents search
A process in which manganese is recovered from manganese nodules after the nodules have been treated to recover base metals such as copper, nickel, cobalt, and molybdenum. The process includes the steps of reacting the manganese in the nodules to yield a carbonate and subjecting the manganese carbonate to flotation. The manganese carbonate froth is collected from the top of a flotation cell, is dried to produce a manganese concentrate, and is sintered to produce a synthetic manganese oxide. Sintering of such concentrates at 1000.degree. C. yields a product containing greater than 50% manganese.The effect of reagent dosage, pH control, and temperature control on the yield of the synthetic manganese oxide is also disclosed.
With the earth's sources of copper diminishing rapidly, much emphasis has been placed on discovering new sources of this metal. One source of copper which has received much attention recently is manganese nodules which are found on the deep floors of oceans and lakes and which contain manganese, iron, copper, nickel, molybdenum, cobalt and other metal values.
Ocean floor deposits are found as nodules, loose-lying at the surface of the soft sea floor sediment, as grains in the sea floor sediments, as crusts on ocean floor hard rock outcrops, as replacement fillings in calcareous debris and animal remains, and in other less important forms. Samples of this ore material can readily be recovered on the ocean floor by drag dredging or by deep sea hydraulic dredging.
The character and chemical content of the deep sea nodules may vary widely depending upon the region from which the nodules are obtained. The Mineral Resources of the Sea, John L. Mero, Elsvier Oceanography Series, Elsevier Publishing Company, 1965, discusses on pages 127-241 various aspects of manganese nodules. For the purpose of illustrating this invention, the complex ores will be considered as containing the following approximate metal content range on a dry basis:
______________________________________ METAL CONTENT ANALYSIS RANGE ______________________________________ Copper 0.8-1.8% Nickel 1.0-2.0% Cobalt 0.1-0.5% Molybdenum 0.03-0.1% Manganese 10.0-40.0% Iron 4.0-25.0% ______________________________________
In general, the base metal values such as copper, nickel, cobalt and molybdenum are recovered from manganese nodules by reducing the nodules to break down the manganese oxide to enable the metal values contained therein to be leached in a leach liquor from which they are recovered. In practicing the present invention, the reduction may be performed by pyrometallurgical roasting operations or by a hydrometallurgical process known as the "cuprion" process which is disclosed in U.S. Pat. No. 3,938,017, the teachings of which are incorporated herein by reference. At this point, it should be noted that U.S. Pat. No. 3,938,017 does not disclose any method of treating the tailings which consist largely of manganese and iron even though manganese is a valuable metal which is employed in great quantities in making steel.
In U.S. patent application Ser. No. 927,272 entitled Production of Ferromanganese From Manganese Nodules, filed on even data herewith by Schapiro et al., a process is disclosed for concentrating manganese from nodule tailings. The present invention is an improvement on the process disclosed in that application.
The present invention is a process which upgrades the cuprion tailings from module processes to enable the manganese values in the tailings to be recovered economically. The process of the present invention provides a profitable outlet for material which heretofore was considered waste. The process includes the step of subjecting the cuprion tailings containing the manganese carbonate to froth flotation to produce a concentrate of manganese carbonate. An important aspect of the present invention involves conditions under which the manganese carbonate is concentrated. By critical control of the flotation reagent dosages, pH of the flotation cell and flotation temperature, the yield of synthetic manganese oxide is improved. Sintering the manganese carbonate concentrate to remove carbon dioxide, moisture and other volatiles produces a synthetic manganese oxide containing greater than 50% manganese. As used throughout this specification and claims, all percentages are by weight unless otherwise specified.
sintering the manganese carbonate concentrate to remove carbon dioxide, moisture and other volatiles to produce a synthetic manganese oxide containing greater than 50% Mn. This synthetic manganese oxide may then be reduced in a blast furnace to produce a ferromanganese alloy with an Mn-Fe ratio greater than 10.
As is stated above, during the leaching step, metals such as copper, nickle, cobalt, and molybdenum are solubilized. These solubilized values are then recovered from the leach liquor in the manner well known in this art. If the nodules are leached in an ammonical leach liquor containing cuprous ions, the residue from the leaching step, which are referred to as the cuprion tailings, may be subjected to steam stripping prior to froth flotation in order to recover the ammonia which is used to prepare fresh leach liquor. Thus, in a preferred embodiment of the invention, a steam stripped residue (cuprion tailings) from the leaching step is subjected to froth flotation.
The nodules may be reduced by a pyrometallurgical roasting process such as that set forth in U.S. Pat. No. 3,734,715 to M. J. Redman entitled EXTRACTION OF METAL VAUES FROM COMPLEX ORES issued May 22, 1973, the teachings of which are incorporated herein by reference. If the process disclosed in U.S. Pat. No. 3,734,715 is followed, the nodules are ground and reduced by gaseous reduction in, for example, a fluid bed roaster. The reduced calcine is then leached in the presence of an oxidizing agent with an aqueous solution of ammonia and an ammonium salt. Leaching solubilizes the metal values such as copper, nickel, cobalt, and molybdenum and leaves the manganese and iron in the solid residue. If leaching was not performed with an ammonium carbonate leach solution, the residue is then subjected to a solution containing from about 0.5 to about 4. M ammonium carbonate to convert the manganese in the residue to manganese carbonate. The residue is then treated in accordance with the procedure set forth above to concentrate the manganese carbonate.
In practicing the invention, the recovery of manganese from manganese nodules may be accomplished by additional steps in the so-called "cuprion" process set forth in U.S. Pat. No. 3,983,017 to L. J. Szabo entitled RECOVERY OF METAL VALUES FROM MANGANESE DEEP SEA NODULES USING AMMONIACAL CUPROUS LEACH SOLUTIONS issued Sept. 28, 1976. In the "cuprion" process, raw manganese deep sea nodules are reduced with cuprous ions (Cu+) in an aqueous ammoniacal ammonium carbonate solution. The cuprous ions reduce the manganese oxides in the nodules which enables metal values such as copper, nickel, cobalt, and molybdenum to be dissolved while leaving iron and manganese carbonate in the solid residue. In the reduction process, the manganese dioxide in the deep sea nodules is reduced by cuprous ions to manganese carbonate according to the reaction:
The "cuprion" embodiment of the present invention is illustrated by the following example. At the outset, however, it is emphasized that the following description relates to a procedure that can be performed in a pilot plant. By extrapolating the results given for the pilot plant, however, one skilled in this art can design a commercial plant for processing large quantities of nodules in accordance with the present invention. The pilot plant is shown in FIG. 1.
The pilot plant was designed for one half ton per day nodule throughput, based on a 31/2 percent solid slurry and with up to a three hour hold-up in the reduction section. The nodules utilized in the pilot plant process are in the condition that they are in after being mined from the deep sea ocean bottom. The nodules are first crushed in the primary crushing circuit to reduce their size to minus one inch. They are then passed into the second grinding circuit which includes an open circuit rod mill 100. The rod mill reduces the nodules from a particle size of minus six mesh to a particle size of approximately minus sixty mesh (U.S. Sieve Series).
The reduction-leach portion of the pilot plant is the location where the nodules are chemically reacted to make the soluble metals soluble in a strong ammoniacal ammonium carbonate solution. This is accomplished by reducing and converting the MnO.sub.2 in the nodules to MnCO.sub.3. The reduction circuit includes six reactors 103-108 connected in series. These reactors are sixty gallon capacity reactors which are used to a 42 gallon capacity in the actual processing. Gas sparging is directed underneath the agitator from the bottom of the reactor with a reduction gas containing 95 percent carbon monoxide. The reactors themselves are outfitted with gravity overflows so that there is a cascading system from the first (103) through the sixth (108) reactor. Normally, each of the first four reactors (103-106) is fed an equal amount of feed stock.
While the nodules are fed to the first four reactors, carbon monoxide is sparged into the bottom of each reactor as required. Preferably, the carbon monoxide is sparged into each reactor under pressure. The slurry in the fifth and sixth reactors is approximately 3.5 percent solids and the average residence time in the system is twenty minutes per reactor. The slurry overflowing the last reactor is flocculated to enhance settling before entering a clarifier. The clarifier is used to separate the liquid from the solids.
In order to reach a continuous steady state, the reactor vessels 103-108 must be loaded with start-up materials. Thus, each of the six reactors are filled with an ammonia-ammonium carbonate solution containing approximately 100 grams per liter total ammonia and between about 15 and 20 grams per liter total carbon dioxide. After the reactors are filled with the ammonia-ammonium carbonate solution, copper metal is added and is partially oxidized. The metal is added as a copper powder and is oxidized to convert some of the copper to cuprous ions. Enough copper metal is added so that 10 grams per liter copper in solutions results. The mixture in each reactor is analyzed to make sure that the cuprous ion concentration is at an acceptable level of about 7 grams per liter. If more cuprous ions are needed, this can be accomplished by passing the reducing gas through the bottom of the reactor.
After the reactor vessels have been loaded for start-up as set forth above, the manganese nodules are added to the first four reactors. The total rate of feed to the four reactors is about 30 pounds per hour of nodules. As the nodules are being fed into the reactors, carbon monoxide is sparged through the bottom of the reactors under a pressure of about 1-2 atmospheres at a total rate of about 70 standard cubic feet per hour.
Approximately 120 gallons per hour of reduction slurry enters the clarifier 110. The solids 112 leave the bottom of the clarifier in the form of a slurry with approximately a 40 percent solids content. The overflow 114 from the clarifier is clear liquid which constitutes the recycle reduction liquor 102. However, after leaving the clarifier, the recycle reduction liquor enters a surge tank (not shown) whereupon it is passed into an ammonia makeup unit 116. Gaseous ammonia and carbon dioxide are sparged into the ammonia makeup unit in order to keep the ammonia and carbon dioxide content of the liquid at a prescribed level. At steady state, that level is approximately 100 grams per liter ammonia and the CO.sub.2 content about approximately 25 grams per liter. After leaving the makeup unit, the liquid is pumped by a metering pump through a heat exchanger 118 into the first reactor 103 and the rod mill 100. The heat exchanger removes heat that was generated in the process and lowers the temperature of the liquid from about 55.degree. to about 40.degree. C.
In the oxidation and wash-leach circuit, the clarifier underflow is combined with second stage wash liquor and the resulting slurry is oxidized with air to convert the cuprous ion in the clarifier underflow to cupric ion to facilitate future processing. The oxidized slurry is then pumped to a countercurrent decantation system (CCD) consisting of seven stages of countercurrent washing units. In the pilot plant, the wash-leach steps are carried out on a batch basis in nine tanks 120 to 128 which are used to simulate a countercurrent wash system. In the wash-leach system, the metal solubilization is completed as the displacement wash process is carried out. Fresh wash liquor 140 is added to the seventh stage of the system as a solution containing 100 grams per liter ammonia and 100 grams per liter carbon dioxide. Liquor is transferred from one tank of the settled slurry every twelve hours to another appropriate tank in the system to effect the countercurrent washing. The carbon dioxide concentration varies throughout the washing system and exits in the pregnant liquor 130 which contains approximately 65 grams per liter CO.sub.2. Pregnant liquor 130 containing the soluble metals to be recovered, is decanted from the first wash stage and is pumped to a surge tank (not shown). Fresh ammonia solution without metals is added (not shown) to the last solids wash stage 121. The metal values in solution range from approximately 0 in the fresh wash liquor 140 to between 4-8 grams per liter copper and 5-10 l grams per liter nickel in the pregnant liquor 130.
After the wash-leach step, the pregnant metal bearing liquor is piped off for further processing as is explained below. The second stage wash is recycled back to the oxidation reactor 132. The residue (cuprion tailings), which are nothing more than reduced nodules washed of most of their non-ferrous metal values and with the manganese converted to manganese carbonate, are sent to a surge tank (not shown). From the surge tank, they are then pumped to a steam stripping operation where the ammonia and CO.sub.2 are driven off. These cuprion tailings are then treated in accordance with the present invention to recover manganese. It should be noted that in this embodiment of the invention, the manganese in the cuprion tailings has been converted to manganese carbonate.
It should also be noted that the pregnant metal bearing liquor 130 contains recoverable metals such as copper, nickel, cobalt, and molybdenum. Initially, the pregnant liquor is treated to recover copper and nickel. Basically, the preferred treatment consists of ion exchange with an organic extractant such as oxime to selectively extract copper and nickel followed by electrowinning to recover the copper and nickel metal values. Details for procedures for recovering these metals are set forth in U.S. Pat. No. 3,853,725 to Ronald R. Skarbo, entitled SELECTIVE STRIPPING PROCESS, the teachings of which are incorporated herein by reference. In this type of procedure, initially the copper and nickel are coextracted by an organic extractant in a series of mixer/settler units. The organic extractant is LIX-64N in a kerosene base which is an extractant sold by General Mills Chemicals, Inc. The copper and nickel free liquor (raffinate) is sent to a storage tank before it is steam stripped.
The organic extractant which contains copper and nickel values is washed with an NH.sub.4 HCO.sub.3 solution followed by an ammonium sulfate solution to remove ammonia picked up during extraction. This scrubbing operation is carried out in another series of mixer settlers. The organic extractant is then stripped with a weak H.sub.2 SO.sub.4 solution (pH about 3) to preferentially remove nickel. Thereafter, the copper is stripped, which is accomplished by using a stronger (160 g/l) H.sub.2 SO.sub.4 solution. The copper and nickel-free organic extractant is recycled to the metal extraction circuit of the LIX process.
The raffinate which contains only cobalt, molybdenum and some trace inpurities that were not extracted into the organic phase is sent into a surge tank for future processing to recover cobalt and molybdenum. In the cobalt and molybdenum recovery circuit, the ammonia and CO.sub.2 are stripped from the raffinate thereby precipitating cobalt. The ammonia and CO.sub.2 are condensed and sent back to the process for recycling. The cobalt precipitate is separated from the liquor and the liquor is subsequently treated with calcium ions to precipitate the molybdenum. The resulting slurry is agitated and then allowed to settle. The solution which no longer contains cobalt and molybdenum is recycled back to the process as fresh wash liquor. Ammonia and CO.sub.2 are added to the solution to bring it up to the prescribed concentration.
Of course, the recovery of metal values other than the manganese product described herein does not constitute part of the invention per se; however, in order for the present invention to be economical, as many of the metals in the manganese nodules as are possible to recover should be recovered along with the manganese product which results from practicing the present invention.
The steam stripped cuprion tailings 150 which are rich in manganese carbonate, are treated in accordance with the present invention to concentrate the manganese carbonate; and, the manganese carbonate concentrate is sintered. A characterization of the steam stripped cuprion tailings is given below:
The manganese carbonate is present as single particles or aggregates of particles not intergrown with phases "A" and "B". The occurrence of the carbonate as a physically and chemically distinct solid permits mechanical separation. Phases "A" and "B" contain the residual base metals Cu, Ni, and Cu along with a large fraction of the iron.
In accordance with the present invention, cuprion tailings 150 are added to a bank of flotation cells, such as the one shown in FIG. 2, which contains water, sodium silicate, and a fatty acid. The mixture is agitated at a high speed to produce a foam or froth. The bubbles in the froth carry the concentrated manganese carbonate to the top of the cells while the remainder of the cuprion tailings, i.e., phases "A" and "B", settle to the bottom of the cells.
Referring to FIG. 1, steam stripped cuprion tailings 150 produced in the pilot plant are upgraded by froth flotation in accordance with the present invention. For a 0.5 ton per day nodule feed to the pilot plant, 0.55 ton (1100 lbs.) of cuprion tailings are produced. [In part of the pilot plant shown in FIG. 1, copper and nickel are removed from the nodules, but carbon dioxide (CO.sub.2) is added to this weight more than making up the difference; hence the cuprion tailings are heavier than the starting material.]0.55 Ton of cuprion tailings per day are continuously fed to a bank of two flotation cells, each containing 40 liters of water. Into each cell is metered a fattey acid and sodium silicate. The fatty acid dosage is within the range of 0.5-3.0 lbs per ton of cuprion tailings and the sodium silicate dosage is between the range of 0.5 to 10 lbs. per ton of cuprion tailings. An amount of mineral acid, such as sulfuric acid, is also added to lower the pH of the cuprion tailings from 9-10 to 6.6-8.4. The pulp density in the cells is in the range of 10-22% solids, and the retention time is in the range of 14-35 minutes.
The froth containing the manganese carbonate concentrate continuously overflows the cells at the rate of 17 lbs/hr (dry basis) and the underflow is removed at the rate of 29 lbs/hr from the bottom of the cells. The underflow is pumped to a settling tank and is eventually discarded to a tailings pond or the like.
The carbonate is sintered at a temperature of 1000.degree. C. to remove CO.sub.2, moisture and other volatiles. Sintering may take place in any number of suitable types of furnaces. Reactions occurring during sintering are:
2. evaporation of water ##EQU2## A method is to pelletize the concentrate in a disc pelletizer followed by induration in a grate-kiln (travelling grate - rotary kiln). The product is hard spheres (3/8"-5/8" diameters) of sintered MnO - FeO mixture with a Mn to Fe ratio greater than 10 with a small amount of oxides of Cu, Ni, Co and the other metals orignally present in manganese nodules.
In the ferromanganese blast furnace, the sintered pellets are charged with coke and limestone, and the oxides are reduced at temperatures in the range of 1550.degree.-1700.degree. C. to the metals. The typical overall reactions are:
All of the MnO and FeO is reduced; thus, the Mn to Fe ratio is greater than ten in the metallic product, which also includes a small amount of impurity metals, Cu, Ni, Co, and Mo. The liquid slag from the process consists of the unreduced SiO.sub.2 (silica) from the pellets plus CaO (lime) from the limestone in the charge.
The present invention is based on a discovery that reagent dosages of the flotation cell is an important factor to control. More specifically, it has been discovered that the use of sodium silicate in the flotation cell segregates the iron in the cuprion tailings from the manganese which overflows the flotation cell. Indeed, by following the present invention, the manganese carbonate that is floated contains less than 1% iron.
Other aspects of the present invention involve other process parameters. In connection with this point, it has been discovered that pulp pH, temperature of the flotation cell, and the amount of fatty acid utilized in the flotation cell are significant parameters in conjunction with the use of sodium silicate.
In accordance with the present invention, fatty acid dosage is between the range of 0.5-3.0 lbs. per ton of cuprion tailings. The sodium silicate dosage is between the range of 0.5-10 lbs. per ton of cuprion tailings.
In connection with fatty acids, this material is widely used in the flotation art and is used to describe a carboxylic acid containing 12 to 18 carbon atoms. These acids are available commercially and are usually obtained as a mixture of acids. Saturated and unsaturated acids that are available include:
______________________________________ SATURATED ACIDS Lauric = C.sub.12 Palmitic = C.sub.16 Myristic = C.sub.14 Margaric = C.sub.17 Pentadecanoic = C.sub.15 Stearic = C.sub.18 UNSATURATED ACIDS Myristoliec = C.sub.14 Oleic = C.sub.18 Palmitoleic = C.sub.16 Linoleic = C.sub.18 Hexadecadienic = C.sub.16 ______________________________________
In accordance with another important aspect of the invention, it has been discovered that the yield of manganese carbonate is improved if the pH of the flotation cell is maintained between the value of 6.6-8.4.
In accordance with another aspect of the invention, it has been discovered that the yield of manganese carbonate is improved if the flotation cell is operated at a temperature between the range of 55.degree.-80.degree. C. This temperature may be achieved by heating the water that is added to the flotation cell prior to the introduction of the cuprion tailings.
Additional examples are given below to illustrate the flotation responses in terms of concentrate grade, recovery of manganese, and the flotation time. In the following flotation experiments, fatty acid was used as the collector and sodium silicate as a dispersant.
A specified dosage of sodium silicate was added to sea water at 80.degree. C., followed by a three-minute conditioning period. This sea water was roughly half of the total sea water to be added and the amount was varied for each test depending on the % solids. Next, the cuprion tailings (about 50% to 56% solids) were slowly added, followed by a five-minute conditioning period. The pulp was then heated up to 65.degree. C. in order to insure a flotation temperature of approximately 60.degree. C. The fatty acid was added, followed by a three-minute conditioning period, and then most of the remaining sea water was added. After one mintue of conditioning, the sulfuric acid was then added for pH control, followed by a five-minute conditioning period. When the sulfuric acid was first added, there was an increase in the height of froth. During the conditioning, this level dropped back to its prior height. To prevent overflow during this time, a small amount of sea water (80.degree. C.) was not added until after the flotation cell was conditioned for one minute after this final sea water addition. The flotation was now ready to begin. The air was turned on and adjusted during the flotation to obtain a steady froth rate. For all tests, the total volume of slurry just before flotation was kept the same. After the flotation, the concentrates and the tailings were filtered, dried and weighed and then sent for chemical analyses and insoluble material measurements.
One set of experiments was conducted to evaluate the effects of fatty acid and sodium silicate on the grade and recovery of manganese concentrate. The experiments were performed with the standard flotation procedure described above. The flotation pulp was kept at 16% solids, and a flotation pH of 8.5 was used. Table I summarizes the results.
TABLE I ______________________________________ Flotation Response as a Function of Fatty Acid and Sodium Silicate Usage Na Test Silicate Fatty Acid Distrib'n. No. ml ml Product Wt. % % Mn. % ______________________________________ 1 10 0.7 Conc. 57.4 32.7 68.9* Tails 42.6 19.9 31.1 2 25 0.5 Conc. 41.9 34.0 52.1* Tails 58.1 22.1 47.9 3 15 0.5 Conc. 48.6 32.8 59.1* Tails 51.4 21.5 40.9 4 20 0.7 Conc. 56.6 32.4 68.5* Tails 43.4 19.4 31.5 5 5 0.5 Conc. 51.6 31.4 60.3* Tails 48.4 22.0 39.7 6 15 0.5 Conc. 48.5 32.2 58.6* Tails 51.5 21.4 41.4 ______________________________________ *% Distribution of Concentrate = % Recovery
Additional experiments were performed at pH 6.6 with varying levels of chemical dosage and percent solids. The range of sodium silicate used was between 10 ml and 30 ml, with the fatty acid to sodium silicate ratio at 0.035. The percent solids ranged from 8 to 24. The standard flotation procedure was used during the tests. The flotation time required for complete flotation was measured for each test. After the flotation, the products were dried, sent for chemical analyses, and the metallurgical balance was calculated.
TABLE II __________________________________________________________________________ Metallurgical Balance on Manganese Carbonate Flotation Test Reagents, ml % Distrib. Flotation No. Wt. g. % Solid Na Sil. Oleic H.sub.2 SO.sub.4 Product Wt. % % Mn. of Mn Time, Min. __________________________________________________________________________ 1 675 16 20 0.7 60 Conc. 56.0 34.7 71.6 21 Tails 44.0 17.5 28.4 2 493 12 10 0.35 45 Conc. 43.2 35.3 56.6 16 Tails 56.8 20.6 43.4 3 867 20 30 1.05 75 Conc. 62.0 33.8 77.9 35 Tails 38.0 15.6 22.1 4 320 8 20 0.7 30 Conc. 62.7 35.4 83.1 12 Tails 37.8 12.1 16.9 5 1070 24 20 0.7 90 Conc. 62.9 32.4 75.7 45 Tails 37.1 17.6 24.3 __________________________________________________________________________
The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
beneficiation of manganese ore using froth flotation technique - sciencedirect
The present study is contemplated to develop a method for flotation of low grade Manganese Ore. Both manual and mechanized workings of manganese mines in India by open cast and underground mining & dump working methods. Froth flotation is the process generally recommended for the beneficiation of low and medium grade ores because of the floatability characteristics of the manganese. The present work has been taken with waste Manganese ore from Garividi mines (Vizianagaram District). Manganese ores of major commercial importance are pyrolusite (MnO2, Mn about 63.2%) & psilomelane. From this study the recovery of MnO2 by using froth flotation technique was (85.41%) achieved. The optimum time of flotation obtained for manganese is 9 minutes. At 9 minutes, the optimum variables obtained are collector dosage of 2.5 gm/ml of feed and frother 2 gm/ml, depressant 1.5 gm/ml and pH is 8. The frother dosage has shown marginal effect on flotation of manganese ore. The collector dosage has shown significant effect on flotation of manganese ore. Flotation of manganese ore shows fine particle size of 45 m give recovery of 85.41% at optimum variables. Natural pH of manganese ore in the flotation process gives better recovery than the higher pH.
More ores are treated using froth flotation cells than by any other single machines or process. Non-metallics as well as metallics now being commercially recovered include gold, silver, copper, lead, zinc, iron, manganese, nickel, cobalt, molybdenum, graphite, phosphate, fluorspar, barite, feldspar and coal. Recent flotation research indicates that any two substances physically different, but associated, can be separated by flotation under proper conditions and with the correct machine and reagents. The DRflotation machine competes with Wemco and Outotec (post-outokumpu) flotation cells but are all similar is design. How do flotation cells and machinework for themineral processing industry will be better understood after you read on.
While many types of agitators and aerators will make a flotation froth and cause some separation, it is necessary to have flotation cells with the correct fundamental principles to attain high recoveries and produce a high grade concentrate. The Sub-A (Fahrenwald) Flotation Machines have continuously demonstrated their superiority through successful performance. The reliability and adaptations to all types of flotation problems account for the thousands of Sub-A Cells in plants treating many different materials in all parts of the world.
The design of Denver Sub-A flotation cells incorporates all of the basic principles and requirements of the art, in addition to those of the ideal flotation cell. Its design and construction are proved by universal acceptance and its supremacy is acknowledged by world-wide recognition and use.
1) Mixing and Aeration Zone:The pulp flows into the cell by gravity through the feed pipe, dropping directly on top of the rotating impeller below the stationary hood. As the pulp cascades over the impeller blades it is thrown outward and upward by the centrifugal force of the impeller. The space between the rotating blades of the impeller and the stationary hood permits part of the pulp to cascade over the impeller blades. This creates a positive suction through the ejector principle, drawing large and controlled quantities of air down the standpipe into the heart of the cell. This action thoroughly mixes the pulp and air, producing a live pulp thoroughly aerated with very small air bubbles. These exceedingly small, intimately diffused air bubbles support the largest number of mineral particles.
This thorough mixing of air, pulp and reagents accounts for the high metallurgical efficiency of the Sub-A (Fahrenwald) Flotation Machine, and its correct design, with precision manufacture, brings low horsepower and high capacity. Blowers are not needed, for sufficient air is introduced and controlled by the rotating impeller of the Denver Sub-A. In locating impeller below the stationary hood at the bottom of the cell, agitating and mixing is confined to this zone.
2) Separation Zone:In the central or separation zone the action is quite and cross currents are eliminated, thus preventing the dropping or knocking of the mineral load from the supporting air bubble, which is very important. In this zone, the mineral-laden air bubbles separate from the worthless gangue, and the middling product finds its way back into the agitation zone through the recirculation holes in the top of the stationary hood.
3) Concentrate Zone:In the concentrate or top zone, the material being enriched is partially separated by a baffle from the spitz or concentrate discharge side of the machine. The cell action at this point is very quiet and the mineral-laden concentrate moves forward and is quickly removed by the paddle shaft (note direct path of mineral). The final result is an unusually high grade concentrate, distinctive of the Sub-A Cell.
A flotation machine must not only float out the mineral value in a mixture of ground ore and water, but also must keep the pulp in circulation continuously from the feed end to the discharge end for the removal of the froth, and must give the maximum treatment positively to each particle.
It is an established fact that the mechanical method of circulating material is the most positive and economical, particularly where the impeller is below the pulp. A flotation machine must not only be able to circulate coarse material (encountered in every mill circuit), but also must recirculate and retreat the difficult middling products.
In the Denver Sub-A due to the distinctive gravity flow method of circulation, the rotating impeller thoroughly agitates and aerates the pulp and at the same time circulates this pulp upward in a straight line, removing the mineral froth and sending the remaining portion to the next cell in series. No short circuiting through the machine can thus occur, and this is most important, for the more treatments a particle gets, the greater the chances of its recovery. The gravity flow principle of circulation of Denver Sub-A Flotation Cell is clearly shown in the illustration below.
There are three distinctive advantages of theSub-A Fahrenwald Flotation Machines are found in no other machines. All of these advantages are needed to obtain successful flotation results, and these are:
Coarse Material Handled:Positive circulation from cell to cell is assured by the distinctive gravity flow principle of the Denver Sub-A. No short circuiting can occur. Even though the ore is ground fine to free the minerals, coarse materials occasionally gets into the circuit, and if the flotation machine does not have a positive gravity flow, choke-ups will occur.
In instances where successful metallurgy demands the handling of a dense pulp containing an unusually large amount of coarse material, a sand relief opening aids in the operation by removing from the lower part of the cell the coarser functions, directing these into the feed pipe and through the impeller of the flowing cell. The finer fraction pass over the weir overflow and thus receive a greater treatment time. In this manner short-circuiting is eliminated as the material which is bled through the sand relief opening again receives the positive action of the impeller and is subjected to the intense aeration and optimum flotation condition of each successive cell, floating out both fine and coarse mineral.
No Choke-Ups or Lost Time:A Sub-A flotation cell will not choke-up, even when material as coarse as is circulated, due to the feed and pulp always being on top of the impeller. After the shutdown it is not necessary to drain the machine. The stationary hood and the air standpipe during a shutdown protects the impeller from sanding-up and this keeps the feed and air pipes always open. Denver Sub-A flotation operators value its 24-hour per day service and its freedom from shutdowns.
This gravity flow principle of circulation has made possible the widespread phenomenal success of a flotation cell between the ball mill and classifier. The recovery of the mineral as coarse and as soon as possible in a high grade concentrate is now highly proclaimed and considered essential by all flotation operators.
Middlings Returned Without Pumps:Middling products can be returned by gravity from any cell to any other cell. This flexibility is possible without the aid of pumps or elevators. The pulp flows through a return feed pipe into any cell and falls directly on top of the impeller, assuring positive treatment and aeration of the middling product without impairing the action of the cell. The initial feed can also enter into the front or back of any cell through the return feed pipe.
Results : It is a positive fact that the application of these three exclusive Denver Sub-A advantages has increased profits from milling plants for many years by increasing recoveries, reducing reagent costs, making a higher grade concentrate, lowering tailings, increasing filter capacities, lowering moisture of filtered concentrate and giving the smelter a better product to handle.
Changes in mineralized ore bodies and in types of minerals quickly demonstrate the need of these distinctive and flexible Denver Sub-A advantages. They enable the treatment of either a fine or a coarse feed. The flowsheet can be changed so that any cell can be used as a rougher, cleaner, or recleaner cell, making a simplified flowsheet with the best extraction of mineral values.
The world-wide use of the Denver Sub-A (Fahrenwald) Flotation Machine and the constant repeat orders are the best testimonial of Denver Sub-A acceptance. There are now over 20,000 Denver Sub-A Cells in operation throughout the world.
There is no unit so rugged, nor so well built to meet the demands of the process, as the Denver Sub-A (Fahrenwald) Flotation Machine. The ruggedness of each cell is necessary to give long life and to meet the requirements of the process. Numerous competitive tests all over the world have conclusively proved the real worth of these cells to many mining operators who demand maximum result at the lower cost.
The location of the feed pipe and the stationary hood over the rotating impeller account for the simplicity of the Denver Sub-A cell construction. These parts eliminates swirling around the shaft and top of the impeller, reduce power load, and improve metallurgical results.
TheSub-A Operates in three zones: in bottom zone, impeller thoroughly mixes and aerates the pulp, the central zone separates the mineral laden particles from the worthless gangue, and in top zone the mineral laden concentrate high in grade, is quickly removed by the paddle of a Denver Sub-A Cell.
A Positive Cell Circulation is always present in theSub-A (Fahrenwald) Flotation Machine, the gravity flour method of circulating pulp is distinctive. There is no short circulating through the machine. Every Cell must give maximum treatment, as pulp falls on top of impeller and is aerated in each cell repeatedly. Note gravity flow from cell to cell.
Choke-Ups Are Eliminated in theSub-A Cell, even when material as coarse as is handled, due to the gravity flow principle of circulation. After shutdown it is not necessary to drain the machine, as the stationary hood protects impeller from sanding up. See illustration at left showing cell when shut down.
No Bowlers, noair under pressure is required as sufficient air is drawn down the standpipe. The expense and complication of blowers, air pipes and valves are thus eliminated. The standpipe is a vertical air to the heart of the Cell, the impeller. Blower air can be added if desired.
The Sub-A Flexibility allows it tobe used as a rougher, cleaner or recleaner. Rougher or middling product can be returned to the front or back of any cell by gravity without the use of pumps or elevators. Cells can be easily added when required. This flexibility is most important in operating flotation MILLS.
Pulp Level Is Controlled in each Sub-A Flotation Cell as it has an individual machine with its own pulp level control. Correct flotation requires this positive pulp level control to give best results in these Cells weir blocks are used, but handwheel controls can be furnished at a slight increase in cost. Note the weir control in each cell.
High Grade Concentrate caused by thequick removal of the mineral forth in the form of a concentrate increases the recovery. By having an adjustment paddle for each Sub-A Cell, quick removal of concentrate is assured, Note unit bearing housing for the impeller Shaft and Speed reducer drive which operates the paddle for each cell
Has Fewer Wearing Parts because Sub-A Cells are built for long, hard service, and parts subject to wear are easily replaced at low cost. Molded rubber wearing plates and impellers are light in weight give extra long life, and lower horsepower. These parts are made under exact Specifications and patented by Denver Equipment Co.
TheRugged Construction of theSub-A tank is made of heavy steel, and joints are welded both inside and out. The shaft assemblies are bolted to a heavy steel beam which is securely connected to the tank. Partition plates can be changed in the field for right or left hand machine. Right hand machine is standard.
The Minerals Separation or M.S. Sub-aeration cells, a section of which is shown in Fig. 32, consists essentially of a series of square cells with an impeller rotating on a vertical shaft in the bottom of each. In some machines the impeller is cruciform with the blades inclined at 45, the top being covered with a flat circular plate which is an integral part of the casting, but frequently an enclosed pump impeller is used with curved blades set at an angle of 45 and with a central intake on the underside ; both patterns are rotated so as to throw the pulp upwards. Two baffles are placed diagonally in each cell above the impeller to break up the swirl of the pulp and to confine the agitation to the lower zone. Sometimes the baffles are covered with a grid consisting of two or three layers each composed of narrow wood or iron strips spaced about an inch apart. The sides and bottom of the cells in the lower or agitation zone are protected from wear by liners, which are usually made of hard wood, but which can, if desired, consist of plates of cast-iron or hard rubber. The section directly under the impeller is covered with a circular cast-iron plate with a hole in the middle for the admission of pulp and air. The hole communicates with a horizontal transfer passage under the bottom liner, through which the pulp reaches the cell. Air is introduced into each cell through a pipe passing through the bottom and delivering its supply directly under the impeller. A low-pressure blower is provided with all machines except the smallest, of which the impeller speed is fast enough to draw in sufficient air by suction for normal requirements.
The pulp is fed to the first cell through a feed opening communicating with the transfer passage, along which it passes, until, at the far end, it is drawn up through the hole in the bottom liner by the suction of the impeller and is thrown outwards by its rotation into the lower zone. The square shape of the cell in conjunction with the baffles converts the swirl into a movement of intense agitation, which breaks up the air entering at the same time into a cloud of small bubbles, disseminating them through the pulp. The amount of aeration can be accurately regulated to suit the requirements of each cell by adjustment of the valve on its air pipe.
Contact between the bubbles and the mineral particles probably takes place chiefly in the lower zone. The pumping action of the impeller forces the aerated pulp continuously past the baffles into the upper and quieter part of the cell. Here the bubbles, loaded with mineral, rise more or less undisturbed, dropping out gangue particles mechanically entangled between them and catching on the way up a certain amount of mineral that has previously escaped contact. The recovery of the mineral in this way can be increased at the expense of the elimination of the gangue by increasing the amount of aeration. The froth collects at the top of the cell and is scraped by a revolving paddle over the lipat the side into the concentrate launder. The pulp, containing the gangue and any mineral particles not yet attached to bubbles, circulates to some extent through the zone of agitation, but eventually passes out through a slot situated at the back of the cell above the baffles and flows thence over the discharge weir. The height of the latter is regulated by strips of wood or iron and governs the level of the pulp in the cell. The discharge of each weir falls by gravity into the transfer passage under the next cell and is drawn up as before by the impeller. The pulp passes in this way through the whole machine until it is finally discharged as a tailing, the froth from each cell being drawn off into the appropriate concentrate launder.
No pipes are normally fitted for the transference of froth or other middling product back to the head of the machine or to any intermediate point. Should this be necessary, however, the material can be taken by gravity to the required cell through a pipe, which is bent at its lower end to pass under the bottom liner and project into the transfer passage, thus delivering its product into the stream of pulp that is being drawn up by the impeller
Particulars of the various sizes of M.S. Machines are given in Table 21. It should be noted that the size of a machine is usually defined by the diameter of its impeller ; for instance, the largest one would be described as a 24-inch machine.
The Sub-A Machine, invented by A. W. Fahrenwald and developed in many respects as an improvement in the Minerals Separation Machine, from which it differs considerably in detail, particularly in the method of aerating the pulp, although the principle of its action is essentially the same. Its construction can be seen from Figs. 33 and 34.
In common with the M.S. type of machine, it consists of a series of square cells fitted with rotating impellers. Each cell, however, is of unit construction, a complete machine being built up by mounting the required number of units on a common foundation and connecting up the pipes which transfer the pulp from one cell to the next. The cells are constructed of welded steel. The impeller, which can be rubber-lined,if required, carries six blades set upright on a circular dished disc, and is securely fixed to the lower end of the vertical driving shaft. It is covered with a stationary hood, to which are attached a stand-pipe, a feed pipe, and the middling return pipes. The underside of the hood is fitted with a renewable liner of rubber or cast-iron. The pulp, entering the first cell through the feed pipe and sometimes through the middling pipes, falls on to the impeller, the rotation of which throws it outwards into the bottom zone of agitation. The suction effect due to the rotationof the impeller draws enough air down the standpipe to supply the aeration necessary for normal operation. A portion of the pulp, cascading over the open tops of the impeller blades, entraps and breaks up the entrained air, the resulting spray-like mixture being then thrown out into the lower zone of agitation, where it is disseminated through the pulp as a cloud of fine bubbles. Should this amount of aeration be insufficient, air can be blown in under slight pressure through a hole near the top of the stand-pipe, in which case a rubber bonnet is fastenedto the lower bearing and clamped round the top of the stand-pipe so as to seal the supply from the atmosphere.
The bottom part of the cell is protected from wear by renewable cast-iron or rubber liners. Four vertical baffles, placed diagonally on the top of the hood, break up the swirl of the pulp and intensify theagitation in the lower zone. The pumping action of the impeller combined with the rising current of air bubbles carries the pulp to the quieter upper zone, where the bubbles, already coated with mineral, travel upwards, drop out many of the gangue particles which may have become entangled with them, and finally collect on the surface of the pulp as a mineralizedfroth. One side of the cell is sloped outwards so as to form, in conjunction with a vertical baffle, a spitzkasten-shaped zone of quiet settlement, where any remaining particles of gangue that have been caught and held between the bubbles are shaken out of the froth as it flows to the overflow lip at the front of the cell. The baffle prevents rising bubbles from entering the outer zone, thus enabling the gangue material released from the froth to drop down unhindered into the lower zone. A revolving paddle scrapes the froth past the overflow lip into the concentrate launder.
Should the machine be required to handle more than the normal volume of froth, it is built with a spitzkasten zone on both sides of the cell. For the flotation of ores containing very little mineral the spitzkasten is omitted so as to crowd the froth into the smallest possible space, the front of the cell being made vertical for the purpose.
Circulation of the pulp through the lower zone of agitation is maintained by means of extra holes at the base of the stand-pipe on a level with the middling return pipes. An adjustable weir provides for the discharge of the pulp to the next cell, which it enters through a feed-pipe as before. Below the weir on a level with the hood is a small sand holeand pipe through which coarse material can pass direct to the next cell without having to be forced up over the weir. The same process is repeated in each cell of the series, the froth being scraped over the lip of the machine, while the pulp passes from cell to cell until it is finally discharged as a tailing from the last one. The middling pipes make it an easy matter for froth from any section of the machine to be returned if necessary to any cell without the use of pumps.
Table 22 gives particulars of the sizes and power requirements of Denver Sub-A Machines and Table 23 is an approximate guide to their capacities under different conditions. The number of cells needed
Onemethod of driving the vertical impeller shafts of M.S. Subaeration or Denver Sub-A Machines is by quarter-twist belts from a horizontal lineshaft at the back of the machine, the lineshaft being driven in turn by a belt from a motor on the ground. This method is not very satisfactory according to modern standards, firstly, because the belts are liable to stretch and slip off, and, secondly, because adequate protection againstaccidents due to the belts breaking is difficult to provide without making the belts themselves inaccessible. A more satisfactory drive, with which most M.S. Machines are equipped, consists of a lineshaft over the top of the cells from which each impeller is driven through bevel gears. The lineshaft can be driven by a belt from a motor on the ground, by Tex- ropes from one mounted on the frame work of the machine, or by direct coupling to a slow-speed motor. This overhead gear drive needs careful adjustment and maintenance. Although it may run satisfactorily for years, trouble has been experienced at times, generally in plants where skilled mechanics have not been available. The demand for something more easily adjusted led to the development of a special form of Tex-rope drive which is shown in Fig. 35. Every impeller shaft is fitted at the top with a grooved pulley, which is driven by Tex-ropes from a vertical motor. This method is standard on Denver Sub-A Machines, and M.S. Machines are frequently equipped with it as well, but the former type are not made with the overhead gear drive except to special order.
The great advantage of mechanically agitated machines is that every cell can be regulated separately, and that reagents can be added when necessary at any one of them. Since, as a general rule, the most highly flocculated mineral will become attached to a bubble in preference to a less floatable particle, in normal operation the aeration in the first few cells of a machine should not be excessive ; theoretically there should be no more bubbles in the pulp than are needed to bring up the valuable minerals. By careful control of aeration it should be possible for the bulk of the minerals to be taken off the first few cells at the feed end of the machine in a concentrate rich enough to be easily cleaned, and sometimes of high enough grade to be sent straight to the filtering section as a finished product. The level of the pulp in these cells is usually kept comparatively low in order to provide a layer of froth deep enough to give entangled particles of gangue every chance of dropping out, but it must not be so low that the paddles are prevented from skimming off the whole of the top layer of rich mineral. Towards the end of the machine a scavenging action is necessary to make certain that the least possible amount of valuable mineral escapes in the tailing, for which purpose the gates of the discharge weirs are raised higher than at the feed end, and the amountof aeration may have to be increased. The froth from the scavenging cells is usually returned to the head of the machine, the middling pipes of the Denver Sub-A Machine being specially designed for such a purpose. The regulation of the cleaning cells is much the same as that of the first few cells of the primary or roughing machine, to the head of which the tailing from the last of the cleaning cells is usually returned.
A blower is sometimes required with the M.S. Subaeration Machine. Since each cell is fitted with an air pipe and valve, accurate regulation of aeration is a simple matter. The Denver Sub-A, Kraut, and Fagergren Machines, however, are run without blowers, enough air being drawn into the machines by suction.
In the Geco New-Cell Flotation Cellthe pneumatic principle is utilized in conjunction with an agitating device. The machine, which is illustrated in Fig. 44, consists of a trough or cell made of steel or wood, whichever is more convenient, through the bottom of which projects a series of air pipes fitted with circular mats of perforated rubber. The method of securing the mat to the air pipe can be seen from Fig. 45. Over each mat rotates a moulded rubber disc of slightlylarger diameter at a peripheral speed of 2,500 ft. per minute. It is mounted on a driving spindle as shown in Fig. 46.
Each spindle is supported and aligned by ball-bearings contained in a single dust- and dirt-proof casting, and each pair is driven from a vertical motor through Tex-ropes and grooved pulleys, a rigid steel structure supporting the whole series of spindles with their driving mechanism. The machine can be supplied, if required, however, with a quarter-twist drive from a lineshaft over flat pulleys.
The air inlet pipes are connected to a main through a valve by which the amount of air admitted to each mat can be accurately controlled. The air is supplied by a low-pressure blower working at about 2 lb. per square inch. It enters the cell through the perforations in the rubber mat and is split up into a stream of minute bubbles, which are distributed evenly throughout the pulp by the action of the revolving disc. By this means a large volume of finely-dispersed air is introduced withoutexcessive agitation. There is sufficient agitation, however, to produce a proper circulation in the cell, but not enough to cause any tendency to surge or to disturb the froth on the surface of the pulp. All swirling movement is checked by the liner-baffles with which the sides of the cell are lined ; their construction can be seen in Fig. 44. They are constructed of white cast iron and are designed to last the life of the machine, the absence of violent agitation making this possible.The pulp must be properly conditioned before entering the machine. It is admitted through a feed box at one end at a point above the first disc, and passes along the length of the cell to the discharge weir without being made to pass over intermediate weirs between the discs. The height of the weir at the discharge end thus controls the level of the pulp in the machine. The froth that forms on the surface overflows the froth lip in a continuous stream without the aid of scrapers, its depth being controlled at any point by means of adjustable lip strips combined with regulation of the air.The Geco New-Cell is made in four sizesviz., 18-, 24-, 36-, and 48-in. machines, the figure representing the length of the side of the squarecell. Particulars of the three smallest sizes are given in Table 27. Figures are not available for the largest size.
the flotation of low-grade manganese ore using a novel linoleate hydroxamic acid - sciencedirect
LHA was investigated as a new collector for rhodochrosite flotation.The selectivity of LHA is better than that of the traditional collector oleate acid.We investigated key factors in flotation and the optimum values were obtained.Chemisorption is the major adsorption mechanism in the flotation.
We designed and synthesized a novel linoleate hydroxamic acid (LHA) which demonstrated high selectivity and strong collecting capacity for the beneficiation of manganese ore by selective flotation. The performance of this LHA and oleic acid (OA) used for anionic froth flotation was compared, and the critical factors of rhodochrosite flotation were investigated. It demonstrated that the use of sodium carbonate instead of sodium hydroxide as the pH regulator, dosages of depressant and collector, and the addition of synergist are essential to the effective recovery of Mn in the flotation. And the concentrate grade of 18.3% Mn had been produced from a feed mixture with 10.7% Mn, and the Mn recovery could be achieved as highly as 97% when the LHA was used for the flotation separation of rhodochrosite under the optimum operating conditions. It was found that compared to OA, the novel LHA achieved superior results. Moreover, the analyses of Zeta-potential, Fourier Transform Infrared Spectroscopy (FT-IR), and X-ray diffraction (XRD) indicated that chemisorption accounted for the flotation mechanism. Besides, results of the Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) revealed that the concentrate obtained had significantly higher proportion of manganese-bearing grains (e.g., rhodochrosite and pyrolusite) relative to the tail and implied that Mn-LHA compounds or chelates might be produced through the interaction between the rhodochrosite and LHA.