Hello, my partner! Let's explore the mining machine together!

[email protected]

cyclone pump for ball mill

ball mill operation -grinding circuit startup & shutdown procedure

ball mill operation -grinding circuit startup & shutdown procedure

After the grinding circuit has been brought up to normal operating conditions, the operator must monitor the various process variables and alarms. Most of these variables are monitored in the mill control room, however, the operator is also required to sample and analyse process streams and read local indicators.

The ball mill is susceptible to variations in ore hardness resulting in various grinds at constant throughput, or alternatively, various tonnages at constant grind. The variation in grind is not directly determined. However, a changing cyclone overflow density, at a constant tonnage rate and feed density, would be indicative of changing ore hardness and in that case the tonnage fed to the ball mill should be changed accordingly.

The ore feed rate to the ball mill is controlled by the weightometer located on the mill feed conveyor which can be manually adjusted with in the control room to give a constant weight reading. The signal from the weightometer increases or decreases the belt feeder speed and adjusts the water addition to the ball mill (as a function of the actual weight reading). Both weight control and the proportion of water can be adjusted in the control room.

The water rationing controller must be adjusted programmatically to give the desired ball mill discharge density (normally 60-65% solids). The ball mill discharge density should be checked manually at regular intervals and adjustment made to water ratio controller setpoint to adjust the ball mill discharge density.

The grinding circuit operator must ensure that the ball mill runs properly loaded and gives the correct ore grind. A major practical indication of mill loading is the sound made by the mill. A properly loaded mill will have a deep rhythmic roar, while an under loaded mill will have a metallic rattling type noise and an overloaded mill will be quite silent.

The operator must manually measure the cyclone overflow and underflow densities regularly. An increase in overflowdensity is indicative of softer ore and will soon be accompanied by a lowering of power draw at the mill and a change of sound indicating that the mill is becoming under loaded. To compensate, feed tonnage must be increased. Similarity, a decrease in the cyclone overflow density is indicative of harder ore and this will be accompanied eventually by a coking of the mill. Feed to the ball mill must be reduced.

In the event of an emergency, the mill feed conveyor is shut down individually or by stopping the operating cyclone feed pump. The ball mill must be shut down separately. All equipmentshutdowns are performed locally or from the MCC located in the mill control room.

grinding and classification circuit

grinding and classification circuit

Our EXAMPLE Grinding and Classification Circuit is designed to grind 500 tonnes of ore per day, operating 24 hours per day, with an availability of 95%. This circuit will grind -5/8 material from the Crushing Plant, classify the slurry in one of two cyclones, and pass 70% of the minus 200 mesh material to the mill feed Thickener Circuit at a rate of 22 mtph. This section is intended to be read in conjunction with the Flowsheet and Piping and Instrument Diagrams.

Detailed Process Description and Control:Crushed ore in the fine ore bin flows througha slot feeder onto a 30 variable speed belt feeder. The bin low level alarm on the mill control panelannunciator will inform the mill that there is a shortage of feed material. The belt feeder has level and pullcord switches identical to the other three conveyors. In addition, the belt feeder is equipped with two speed switches; one at each pulley, in order to measure and alarm the difference in pulley speeds as a low speed may be normal for this drive. A belt weigh scale under the conveyor measures the weight of material passing over the idlers and coupled with the belt speed measures the total weight passing on the belt. The ball mill feed rate is set via the weight controller at the mill control panel which adjusts the speed of the belt. A digital counter or totalizer displays the results as total tonnes of ore passed and a recorder maintains a permanent record of ball mill feed.

Ore from the belt feeder enters a 10-6dia. x 13-0 ball mill, which grinds the -5/8 ore to 70% minus 200 mesh. Barren solution is added to the ball mill to produce a slurry of 60% solids. The solids content of the ball mill discharge is controlled by a ratio control loop, whereby barren solution addition is proportional to the ball mill feed. The set point of the controller is the percent solids desired in the ball mill. An orifice plate measures the barren solution flow rate and the controller calculates how much barren solution is required to make the desired slurry, based on the weight of material coming through, and modulates a motorized butterfly flow control valve in the barren solution line accordingly.

The ball mill is an overflow type discharge mill, and is designed for a 45% ball charge. Balls should be added on a regular basis as they are consumed in the mill. The balls are added with a one ton ball bucket, lifted by an overhead crane, and discharged into the ball mill feed chute. The ball charge is self-limiting a greater than 45% ball charge will cause the excess balls to discharge over the trommel screen and out of the mill.

Ground ore passes through the trommel screen onto a chute and is fed to a distributor box above the cyclone feed pumpbox. The pumpbox has two distinct compartments, each equipped with its own 30 HP cyclone feed pumpat its discharge. Normal operation requires the use of only one compartment at a time. Air cylinder valves on the distributor box are manually operated depending on which pumpbox compartment is being used. On changing compartments the distributor valves and cyclone feed pumps must be manually switched over, and the now unused pumpbox compartment must be pumped dry. Gland seal water to the pumps must also be switched over with their associated valves.

Barren solution is used as gland seal water for the two cyclone feed pumps. Each gland seal water line to the pumps is equipped with a sight flow glass; to ensure gland water is flowing to each pump, a dole valve; to control the flowrate of gland water to each pump; and a common pressure gauge; to ensure that sufficient gland seal water pressure is applied to the pump seals.

Although the cyclone feed pumps will self-regulate flow according to the level in the pumpbox, high and low level switches in each compartment will alarm at the control panel annunciator should a problem occur. The 10 HP 2 grinding area sump pump and the crushing area sump pump discharge into the distribution box, along with barren solution. A control loop regulates the flow of barren solution to the cyclone feed pumpbox.

The discharge of each cyclone feed pump is piped separately to its own 15 diameter cyclone, at a normal rate of 122 cubic meters per hour and 52% solids. Should both pumps shut down simultaneously, or the ball mill clutch be disengaged, the feed conveyor will be shut down. The cyclones separate the slurry particles by size; the coarse particles flow through the cyclone underflow to an underflow collection launder, and are then fed back to the ball mill for regrinding. Cyclone overflow (70% minus 200 mesh) is collected in an overflow collection launder, and flow by gravity to a 16 meter diameter thickener. The pH level in the overflow collection launder is monitored, and an indicating transmitter sends an alarm signal to the mill control panel annunciator if the pH level drops below 10.5 (basic).

In order for the cyclones to separate the particles by size effectively, the density of the cyclone feed slurry must be consistent, approximately 52% solids. This is controlled by measuring the slurry density in either cyclone feed line and controlling the amount of barren solution to the cyclone feed pumpbox. The density measurement is achieved using a nuclear source and detector/transmitter, saddle mounted to each pipe. Each transmitter feeds its signal to the controller, which decides which signal to use depending on which pump is running. The output of the controller modulates a butterfly control valve, in the barren solution line, adjusting the barren flowaccordingly. The cyclone feed density is recorded on a recorder which also records the thickener underflow density. Adjustment of the cyclone apex, utilizing air operated pinch valves, will also shift the particle size separation point coarser or finer.

The 15 HP 2 grinding area sump pump is designed to pump 35 cubic meters per hour, and in AUTO regulates its sump level with high and low float level switches. This pump can feed material to the cyclone feed pump-box or to the tailings box.

1 or 2 primary cyclone feed pump in layout - grinding & classification circuits - metallurgist & mineral processing engineer

1 or 2 primary cyclone feed pump in layout - grinding & classification circuits - metallurgist & mineral processing engineer

During mill circuit design, many people prefer to have two pumps to one cyclopac (group of cyclones)- one operating and one standby, while many people prefer to install only one pump for one cyclopac (hydrocyclone-pac).

Pump down plant down. piping is minimal through Tech-Taylor Valve. Have two variable speed drives VSD or switching gear between both.. The pumps are high wear, impellers,liners etc,, not much extra piping is required as an adequate valve system on one pipeline is sufficient, Tech-Taylor valves do a good job on the discharge, be sure to install extra cyclones in the pack as they are high wear as well. You will need to size the whole plant accurately so it works as one, If in doubt, it's cheaper in the long run to consult an expert. It's quick to change a VSD from one pump to the other.

The answer to your question will depend on grinding circuit capacity, abrasiveness of the ore, risk appetite of the operator and maintenance practices on site. For example, I would probably make different decisions for 2,000 TPD and 80,000 TPD (single line) circuits. I have done several trade-off studies on this topic and it is always a contentious issue. Considering saving on pipes etc and less building space with compact layout, one pump option is often better. Necessary spares may be maintained for treplacement when required for smooth operation.

The pump size you want is the pump size you need, depending on Tph, abrasion, recirc etc. But from an operational cost, the payback of a duty, standby system is half a dozen shuts for pump rebuild. I like two pumps with individual VSD's, but have used switching gear, the standby then goes DOL. You can get away with no standby, but its the Mills that pay the bills. This plant has a strange setup, in it is a closed circuit, high aspect SAG, with the p80 at 75um, so we can carry a large recirc depending on the orebody being processed. So our pumps are on the need a lifting device to rebuild size, many hours to rebuild. But the smaller the pump the smaller the costs the smaller the loss, to scale a loss is a loss.

1. a 40 000 tpd plant with a 15 MW primary SAG mill and 2 pcs 10 MW secondary ball mill. If you try to change the H/C feed pump without stopping or just during a short shut down of the grinding line, you may not get a single drop of slurry into the stand by pump because the feed sump is half full of ball scrap and coarse rock, blocking the pump inlet pipe of the standby pump. Therefore the plant has a tactics to change the standby pump to operation during the SAG mill relining shut down. They never even install the standby pump, but keep a fully revised pump on the floor of the pump level waiting for the liner shut down.

1. A 3 000 tpd plant with a 0.7 MW rod mill and a 1.5 MW ball mill. If you try to change the H/C feed pump during continuous run, you will just find out that the chamber of the autoball valve is half - full of rod scats moving nowhere and leaking badly.

The only realiable way of designing H/C feed pumping or any other item inside or outside the plant walls is through tens of years of on the floor experience. If that is not available at the moment when the electrical pen of the CAD designer makes the first move, it is a step to 180 degrees wrong direction. And what is more, even if the experience is available, a project team composed of guys from all disciplines (project management, plot plan, architecture, civil, process, piping, electrical, automation / instrumentation, HVAC), without intensive, honest and communicative cooperation, will produce a marvel of poor construction.

Thank you all for your comments. Very good input and discussions. What I hope to see more are: hours you needed to replace the pump, how well you can predict the pump worn-out, if you actually experience un-expected pump down for a single pump layout, or for a double layout, whether you actually experieced block-off of Tech Taylor valve, block-off at pump suction when you try to switch to the second one.

For small pumps, we allow vertical discharge, so the layout is pretty simple. When pump is relative large (do not have a clear cut-off, I'd say for a plant of 10,000tpd), we like to have horizontal pump discharge, and the layout becomes a difficult job. For further larger system, say 40,000 tpd, when a Tech Taylor is not available for the pipe size, the layout becomes a pain.

Worked and talked to quite a few well experience process engineers who worked on single pump plants, their comments are quite positive on such layout. Worn-out of pump liners or impellers can be predicted very well based on experience and monitoring of the motor power/speed and planned shut-downs actually affect little of the overall plant availability (sometimes impellers/casing liners may be replaced prematuredly when there is a shut-down for mill maintenance - does this happen in your operation?).

While some well experienced engineers, based on their negative experience on single pump operation, strongly oppose such layout. They want double pump option at all cost -- no matter how difficult the layout job is - let alone the extra budget.

for a single layout case, we replace the whole pump for relative small (say 14") pump or whole wet end for the huge one (such as 650 Warman). Time spent on replacing the 14" pump is approximately 2 hours in a Arizona plant where I worked for a few months.

Another whole issue is sump design, particularly if you get into the concept of one SAG to two ball mills, with two cyclopacs. Should the sump be split, which then leads to how do you distribute the SAG discharge, or should it be a single sump, which leads to how do you prevent build up on pump inlet if that side is down?

It's all about ROI. when someone says "the mills pay the bills" please pay attention. If you can afford to have the place sitting while a pump is changed that's nice. Your lucky. Reality is that for most operations the loss for a shutdown (even scheduled) always hurts but it may be necessary. Goal is maximum safe operational hours.

1. hours to change out a pump in a 28,000 TPD concentrator would not be acceptable as at the current metal prices this operation produces $750 a minute worth of metals and would result in a production loss of $90,000

And with only a single pump the trend is to "limp" it through until the scheduled down, resulting in other production losses (which will poor separation at cyclones, loss of recovery, lowered throughput, clean up of spilled material etc.)

At one operation the increase in overall plant availability from 85% to 92% resulted in a very profitable mine life extension of over four years. (waste became ore because it could then be mined at a profit)

Blocked standby pump suctions can be a problem in large copper porphyry concentrators where the primary grind is quite coarse. The problem can be mininmised by using short straight suctions and having plenty of air and water available at the sump to lance the blockage. A more elegant solution is to design a deep conical or prismoidal sump where turbulence at the suctions keeps the standby relatively clear. This design however, for a given slurry retention time, has the undesirable effect of raising the centreline of the mills discharging into the sump (adding to capex).

Great comments. Using a standby pump seems to have more flexibility to overcome pump maintenance. Any shut down because of pumping maintenance is not acceptable. The pumps are scheduled equipment (I mean by following P.M based on experience). Using more cyclones in cyclopac also can help. Retrofitting a new pump in high capacity circuits also depends on sump and other pumps layout because of more spaces that will be needed.

you may have to install adequate flush lines to the inlets to back-flush. (On a 16" suction for a SAG discharge a 6" high pressure line was adequate to move the settled material, fill and keep the pump from cavitation and stir up the material until the material from the sump reached the pump).

Operations need to isolate and drain pumps as quickly as possible when they go down. I am a big fan of air actuated valves with automatic fail to needed position. I.E. on power failure the suction and discharge valves close, drain valve opens and flush line opens for set time.

after a bump test of the pump to ensure it is ready to run the suction and pump need to be full prior to the switch (flush water). If the pump cavitates it will not build adequate pressure to move the ball and small amount of buildup on the discharge side.

I.E. in one operation a Tech Taylor valve was 10 m up from the pump and under the floor above. All maintenance had to be done by chain fall winches and was a pain for the operations personal to reach if there was an issue. solution was to extend the pump discharge lines by 2 m and put the valve just above the floor. Access by operations and maintenance personnel greatly reduced issue with the valve.

There are many great plants where changing pumps on the run is not an issue, there are plants where someone in their wisdom has made a change and created a monster, why reinvent the wheel. Mike'have a look at a plant that has no such issue and copy that design, How many times have we seen a good plant moved to a new location and the engineers have made a couple changes for various reasons and that plant becomes difficult to run and visa versa a bad plant has been relocated and the engineer has made it operator friendly, thus becoming more efficient. I have not had blocked standby pumps or techtaylor valves and how does one block a discharge line. These issues are employees, may it be the engineer, or the operator, dump valves and flush lines are basic, stick to basics it's not that difficult.

DISCLAIMER: Material presented on the 911METALLURGIST.COM FORUMS is intended for information purposes only and does not constitute advice. The 911METALLURGIST.COM and 911METALLURGY CORP tries to provide content that is true and accurate as of the date of writing; however, we give no assurance or warranty regarding the accuracy, timeliness, or applicability of any of the contents. Visitors to the 911METALLURGIST.COM website should not act upon the websites content or information without first seeking appropriate professional advice. 911METALLURGY CORP accepts no responsibility for and excludes all liability in connection with browsing this website, use of information or downloading any materials from it, including but not limited to any liability for errors, inaccuracies, omissions, or misleading statements. The information at this website might include opinions or views which, unless expressly stated otherwise, are not necessarily those of the 911METALLURGIST.COM or 911METALLURGY CORP or any associated company or any person in relation to whom they would have any liability or responsibility.

a new generation of cyclone feed pumps - mining magazine

a new generation of cyclone feed pumps - mining magazine

After years of dealing with poor performing pumps, requiring a costly outage every 800 hours, leaders of the copper mine turned to GIW for help. They needed a pump that could help them maintain a more reliable shutdown schedule and minimize expenses. GIW's MDX-750, the world's largest mill pump, not only met the customer's goal - but exceeded it - saving this massive Chilean copper mine an estimated US$6 million per mill line.

As a company, GIW has worked diligently to improve its pumps used in cyclone feed applications. This focus has been on using better metallurgy and variable geometry for the wet end during operation. Over the years, GIW has developed and tested new materials to improve pump performance.

Ultimately, GIW scientists developed a brand-new material technology. The impressive and innovative material is called Endurasite, and it's capable of resisting the effects of abrasion for extended periods. When applied to the MDX-750 high wear wet end parts, this specially processed, ultra-wear-resistant white-iron alloy vastly improves pump wear life and, in turn, extends time between shutdowns.

"This was not only difficult for the customer but a challenge for GIW as a supplier," says Hernan Palavecino, GIW South American Regional Sales Manager. "Because this was an unprecedented project in the market, every extra hour of operation was a discovery and the risk of unexpected failure or shutdown was present every step of the way."

The customer never had a need to be concerned, though; the GIW team remained present during all testing to perform maintenance and ensure optimal results. And as Palavecino points out, the results were certainly optimal. "We set a target of 4,500 hours for the first test cycle, but during the campaign, we saw that it was possible to extend the cycle to over 5,000 hours without operational risk," he says. For this test GIW was pitted directly against their competitor's cyclone feed pump. Due to the final testing results and GIW's on-site support, the customer has adopted GIW technology.

GIW experts not only achieved the customer's goal but managed to exceed it - cutting annual shutdowns in half and drastically improving the total cost of ownership. GIW's continual development mindset has taken the mine's pumps from 800 to 5,000 hours of continuous operation. It's an achievement - and long-term responsibility - that GIW doesn't take lightly.

"Reaching this target is the result of several years of continuous improvements and focusing on the customer," explains Palavecino. "It was achieved and exceeded because of the commitment and teamwork between the customer and supplier."

Copyright 2000-2021 Aspermont Media Ltd. All rights reserved. Aspermont Media is a company registered in England and Wales. Company No. 08096447. VAT No. 136738101. Aspermont Media, WeWork, 1 Poultry, London, England, EC2R 8EJ.

ball mill circuit operation | henan deya machinery co., ltd

ball mill circuit operation | henan deya machinery co., ltd

Very often in SAG circuits, the ball-mill circuit is neglected. In many operations where economics dictate that throughput is worth more economically than the required sacrifice in grind, the focus shifts to throughput so much that the available ball mill power is not used to the fullest extent. Even in those operations where a firm grind target is not adhered to and attainable throughput governs the balance of the circuit, it is foolish not to take full advantage of the installed grinding power. Ores for which recovery is grind insensitive in the range of the typical operation are unusual.

Given that mills are charged to the target ball charge with reasonably sized media, and the feed to the ball mill circuit is not so coarse as to cause constant scatting, the key to efficient ball-mill circuit operation is efficient classifier operation. The standard classifier for ball mill circuits is the hydrocyclone. Ensuring that the finest and most efficient cyclone cut involves selecting the appropriate cyclone configuration for the ranges of grinds that will be encountered. The apex (spigot) size can be manipulated to deliver the maximum underflow density at the target operating conditions, with the vortex finder tailored for the desired product size. With a given configuration, adding the maximum amount of water (subject to cyclone feed-pump limitations, the minimum overflow density, and cyclone pressure) will generally result in attaining the finest possible grind. Employing a control system to maximize water addition to the cyclone feed pump (subject to pump capacities and downstream densities constraints) is often employed successfully to maximize ball mill circuit grind.

There is strong evidence supporting the concept of using a mixed-size make-up ball to attain incremental grinding efficiencies in ball mills. There is little reason to believe that the steady-state media size distribution resulting from the wear rate of the make-up ball size corresponds to the optimum ball size based on the mills feed and target grind. In general, a mixed make-up ball-charging regime improves grinding efficiency, with greatest benefits seen for single-stage milling applications with large size reductions.

Nonetheless, most operations tend to use a single-sized make-up ball for reasons of convenience. There is less conclusive evidence for the removal of fine steel from ball charges. While some operations claim an anecdotal benefit from removal of fine steel, unpublished studies by the author indicate a substantial benefit from the use of fine media (less than 12mm) as a supplement to a conventionally sized make-up ball when grinding a gold ore to an 80% size of 75 mm. It is possible that removal of ball chips, which may tend to float due to a shape factor and likely contribute very little to grinding, could result in an improvement in grinding efficiency.

centrifugal concentrator | henan deya machinery co., ltd

centrifugal concentrator | henan deya machinery co., ltd

Knelson centrifugal concentrator is a centrifugal mineral processing equipment, it has features of high recovery rate, easy operation, etc. It is mainly used for recycle heavy materials in mineral particles, especially good for placer gold mining. Deya Machinery produces automatic discharging and semi-automatic discharging concentrator.

Centrifugal concentration has been proved an effective technique for recovering fine or ultra-fine heavy minerals for many years. In centrifugal concentration, the centrifugal force acting on a particle can be much greater than the acceleration of gravity; as a result, the settling velocity of particles increases greatly. The higher the centrifugal intensity (the centrifugal acceleration over gravity acceleration, often noted g), the finer the particles that can be recovered.

Since the first unit was commissioned in 1980, thousands of Knelson concentrators were installed. In recent years, the Knelson Concentrator has become the preferred gravity device to recover free gold. Compared to other centrifuges, it possesses quite different features either in design or separation mechanisms.

One unique feature of the Knelson Concentrator is its riffle construction andtangential fluidization water flow in the separating bowl,which partially fluidizes theconcentrate bed. As a result,the unit can achieve high recovery over a wide size range.Industrial recoveries of gravity recoverable gold have been measured as high as ninetypercent. Recovery is strongly influenced by feed rate and gangue density.

Knelson Concentrators have a large throughput capacity,e.g. a 76 cm KnelsonConcentrator can treat up to 40 tonnes of material per hour. Locating the Knelson within the grinding circuit can eliminate the need for other gravityrecovery devices. Another advantage of the Knelson is its ability totreat a wide size range of material without desliming,something most other centrifugescannot do.

The Manual Discharge Knelson is especially suitable for the recoveryof very low grade high density particles, typically on account of the limited concentratevolume. It develops a centrifugalintensity of 60 g,and can process feeds finer than6 mm. The feed is introduced to the bottom of the bowl by gravity through a downcomer. The feed requires only enough water for transport, and any density from 0 to 70% solids can be handled without any detrimental effect on operating efficiency.

Under the effect of the centrifuga1 force field. the heavy particles will report to the riffles as concentrate. whereas gangue minerals will flow to the outer rim as tails. The centrifugal force that would cause packing of material in the rings is partially offset by the fluidization water. The water jets are tangentially injected into the bowl from small holes on the Knelson Concentrator bowl in a direction opposite to the bowls rotation.

The resulting fluidized bed behaves as a heavy liquid whose density is that of thepulp, and hindered settling conditions prevail. It is in this constantly agitated environmentthat concentration takes place with the particles of higher specific density displacing thelighter ones.

Very high concentration ratios can be achieved, even above 500, at little or no loss of recovery. The Manual Discharge Knelson is a batch machine. The feed must be interrupted while concentrate removal takes place. This takes from 5 to 10 minutes, and is accomplished by unlocking an access door, removing a drain plug and flushing the concentrate to a secure gold room via a pipeline or into a container.

The manual discharge of its concentrate makes frequent flushing difficult,yieldingloading cycles of two hoursor more. Although virtually no gold operation can boast gold feed grades that would overload the Knelson over such recovery cycles, loss ofrecovery due to concentrate bed erosionshould requireshorter recovery cycles.

The Knelson Concentrator requires little maintenance. It is sturdy and has onlyone moving part,the rotor. Its drive shaft passes through two pillow-block bearings, wetted surfaces are made of stainless steel, and the concentrating bowl is moulded inwear-resistant polyurethaneor stainless steel.

The removal of concentrate can be accomplished automatically in less than twominutes. The feed is first diverted (generally to a cyclone pump sump or bal1 mill), the fluidization water flowrate and the speed of rotation are reduced. The concentrate is then flushed from the concentrating rings past the feed deflector and piped directly to a secure gold room.

The machines utilise the principles of a centrifuge to enhance the gravitational force experienced by feed particles to effect separation based on particle density. The key components of the unit are a cone shaped concentrate bowl, rotated at high speed by an electric motor and a pressurized water jacket encompassing the bowl. Feed material, typically from a ball mill discharge or cyclone underflow bleed, is fed as a slurry toward the centre of the bowl from above. The feed slurry contacts the base plate of the vessel and, due to its rotation, is thrust outward. The outer extremities of the concentrate bowl house a series of ribs and between each pair of ribs is a groove. During operation the lighter material flows upward over the grooves and heavy mineral particles (usually of economic value) become trapped within them. Pressurized water is injected through a series of tangential water inlets along the perimeter of each groove to maintain a fluidized bed of particles in which heavy mineral particles can be efficiently concentrated. The Knelson concentrator typically operates as a batch process, with lighter gangue material being continuously discharged via overflow and a heavy mineral concentrate periodically removed by flushing the bowl with water.

cyclone pressure in water balancing - grinding & classification circuits - metallurgist & mineral processing engineer

cyclone pressure in water balancing - grinding & classification circuits - metallurgist & mineral processing engineer

hi guys. i am working at a small scale mining industry. they have been operating at about 80t/h feed to ball mill. the cyclones operates at about 85MPa feed pressure. 2 cyclones run at a time. however they don't maintain water balance .we all know that the principle is "the less the feed the less the water, but proportionally and vice versa". but they keep saying if the water is less proportional to the feed, the cyclone feed pressure will go down, so will result in undesired classification. this is why they add same amount of water all the time whether the feed is less or more. but i suggest, what if we use one cyclone at a time, in case the feed to ball mill goes down from 80t/h to 30t/h. since they use almost same amount of water even though the feed to mill gets low to 30t/h, cyclone overflow becomes diluted and results in a very low density ( it was supposed to be 23%, but goes down to 10-11%), which becomes out of the designed parameter.in my point of view, with the correct water balance i get my cyclone overflow 23% all the time. but how about the cyclone feed pressure? i think we cant increase the pump speed to maintain the pressure, because tonnage to mill is low. The cyclone feed sump can be left empty. here is the help i need guys. Do I have other alternatives to get the designed cyclone pressure or any other ways by keeping cyclone overflow 23% all he time. thanks a lot

I am sure you already know what needs to happen. Any contninous system operates well if it is allowed to attain equilibrium and allowed to continue in equilibrium. any changes that affect equilibrium will affect efficiencies and productivity. one way the deal with is to make sure that you control your feed into the mill from whatever your source is constant, ie.e you need surge capacity before the mill so that feed into you mill is constant as this is critical.

Thanks brighton. Thats a a good idea. But the real problem on the ground is there has been a continuous failure in the crushing section due to liner wear and motor failure, chocking....etc. we fill up the whole stock pile, but the failure on the crusher sometimes lasts 2-3 days. In Which case we will runout of ore if we go with the same tonnage like before at 80-90t/h. This is the problem.

you are totally correct. you want to maintain pressure to achieve same size dist'n. If you add more water and cut cyclone feed density you will make a finer product, dont know if that is good or bad, but downstream density will fall. Large mills have many cyclones in a cyclopac. So removing one is no big deal and gives a stepwise flow control. You are a bit hooped having two cyclones. Your thinking however looks correct

I appreciate that mike. Thanks. We have 6 cyclones. Howevere 2 are running at atime. If I try to add cyclone, my pressure will definitely go down. Its why I choose operating using one cyclone. Our problem is that the size of the apex is static. We cant increase or make it smaller. Nothing automatic means of controlling the apex is attached to it.Of is the same all the time.

The turndown inthroughput is alsolikely having a negative impact on subsequent processing circuits as well.The impact of this instability on their performance probably results inhigher losses (and other measures of performance) during these times.

Thanks Robert that helps a lot. I think I need to see how much money I am going to save or loss, if the mill shut down. i will also have a word with the Grinding Technicians on how bad will that influence on mill operating conditions. Because if this is going to happen, we are going to stop 2-3 days a month. That feels a bit strange right? Thanks again.

Effectively you are right, it is key to work with a balanced water balance to maintain pulp density and grading conditions, defined in the design, but it is also important to maintain the working pressure condition of the cyclone and as it is a equipment that is sizing volumetrically, the correct action is to withdraw equipment from the operation as the feed decreases.Therefore, the action of operating with a cyclone for a feed of 30 t / h is correct, however, the initial feed was 80 t / h, which means two things:1. The mill is being sub-used energetically2. Each cyclone in normal operation classifies a mass flow equivalent to 40 t / h3. A flow of 30 t / h is 25% lower than its normal operating condition4. The above condition will not allow work to the design pressure condition (85 MPa)5. Therefore the classification condition will be deficient and consequently the particle size (P80) for the next stage will be inadequate6. All of the above will negatively impact the metallurgical recovery of the process and the cost of operation (OPEX)7. Increase pumping speed will only exacerbate the problem further, causing problems of accelerated pipe wear and cavitation problems of the pumps when the pumping box is emptied

SMALL CYCLONES:1. Dimension and install a smaller cyclone, suitable for the new feed rate of 30 t / h, if this condition is transient, or replace with a new battery of smaller cyclones, if the condition is permanentBATCH OPERATION:1. It would be advisable to evaluate a batch operation strategy at a processing rate of 80 t / h, starting the operation with the collection of full fine ore (80 x 24 = 1920 tons), which would allow a 64 hour autonomy (2 ,7 days).2. In addition, during the same 64 hours of operation, an additional 1920 tons of ore could be collected (30 x 64 = 1920 tons), which would achieve a further 64 hours of autonomy3. The proposed strategy would allow a total autonomy of 128 hours (5.3 days) operating at 80 t / h with 64 hours (2.7 days) of detention, intended for maintenance and replenishment of fine ore collection, among other activities4. To clear any doubts about the advantages and disadvantages of both options, it would be advisable to conduct a trade off, comparing energy consumption, energy efficiency, availability, utilization and opex.

To maintain the pressure at the hydrocyclone inlet , you should maintain the % solids in the range of 45-55 % at the hydrocyclone inlet and it can be very easily monitored ene . Densitometer will sense the pulp density and based on that it will operate the water control valve at the ball mill outlet and in that way you can automatically control the Feed parameters . This is a permanent solution to your problem .

Thanks for the suggestion ashutosh. But I dont think u understand the problem. My cyclone feed percent is 55%. But that works out when feed is 90t/h. If feed goes down to 40 t/h , you cant do the correct water balance and continue with 55%. The pump is a cyclone pump. Its impeller is big. You try to maintain the pressure through the velocity of the impeller as usual, your sump will be left empty sooner. the pump will suck air and cause problem. I dont want this to happen.this is why I ask the professionals for other options of there is any. I in the comment I wrote before, my apex is static. If it can be altered, it was the best shot. Anyways Thanks for the suggestion.

DISCLAIMER: Material presented on the 911METALLURGIST.COM FORUMS is intended for information purposes only and does not constitute advice. The 911METALLURGIST.COM and 911METALLURGY CORP tries to provide content that is true and accurate as of the date of writing; however, we give no assurance or warranty regarding the accuracy, timeliness, or applicability of any of the contents. Visitors to the 911METALLURGIST.COM website should not act upon the websites content or information without first seeking appropriate professional advice. 911METALLURGY CORP accepts no responsibility for and excludes all liability in connection with browsing this website, use of information or downloading any materials from it, including but not limited to any liability for errors, inaccuracies, omissions, or misleading statements. The information at this website might include opinions or views which, unless expressly stated otherwise, are not necessarily those of the 911METALLURGIST.COM or 911METALLURGY CORP or any associated company or any person in relation to whom they would have any liability or responsibility.

Related News
  1. ball mill 29
  2. ball mill trunnion for sale quartz crusher
  3. metal steel ball dia 6mm
  4. ball mill working philosaphy
  5. ball mill for raw mill in cement plant supplier fo
  6. rodillo negro
  7. cost of grinding in gold production stone crusher for sale
  8. new quartz mineral processing production line in tokyo
  9. ball bearing
  10. monrovia high quality small kaolin ceramic ball mill manufacturer
  11. new ball mill in south africa
  12. air filter with dust briquetting machine
  13. copper beneficiation essay
  14. specifions of stone crusher vibrator
  15. concrete mobile crusher e porter in india buying and selling
  16. weight of a ball mill grinding ball
  17. bucket crusher for hire chandigarh
  18. portable gold ore cone crusher price in
  19. gold classifier equipment equipment compressor
  20. small coal hammer mill crusher