coal crusher machine,coal grinding mill plant, mobile coal pulvarizer manufacturer in india, indonesia,china
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure. Coal is composed primarily of carbon along with variable quantities of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen.
Coal crushing process is the important coal processing in coal energy industry. SBM offer the complete coal mining equipments in the coal crushing process. Coal crushing plant acts as the key crushing plant in this process.
Primary coal crusher works in the first stage of coal crushing process. Coal raw materials are firstly poured into vibrating feeder, which they will be fed into primary coal crusher continuously and evenly. Primary crusher is usually jaw crusher or impact crusher, producing lump coal cinder.
Secondary coal crusher crushes the lump coal cinder transported by coal conveyor. Secondary coal crusher usually includes hydraulic impact crusher, cone crusher and JC jaw crusher. It produces sand size coal particlc which can be used in pretreatment of coal directly.
Tertiary coal crusher resizes coal particlc into coal powder. Tertiary crusher is used in special occasions like the coal grinding mill has special requirements on the feeding size. Cone crusher can act as the tertiary coal crusher because of its fine final outlets.
Coal is divided into 14 categories. Lignite, long flame coal, non-caking coal, weakly caking coal, 1/2 caking coal, gas coal, gas and fat coal, 1/3 coking coal, fat coal, coking coal, lean coal, meager lean coal, lean coal and anthracite .
Can be divided into different categories according to the structure of the rock, candle coal, Fusain, dark coal, bright coal and vitrinite. Containing more than 95% vitrinite vitrinite coal surface bright, solid structure, containing the vitrinite and light quality for bright coal with the coarse dark coal, containing Fusinite Fusain by many small spore-forming particles cannel.
The coal is distributed in Algeria,Botswana,Egypt,Madagascar,Malawi,Morocco,Mozambique,Niger,Nigeria,South Africa,Swaziland,Tanzania,Zambia,Zimbabwe,India,China,Russia,Kazakhstan,Indonesia,USA,Canada,Mexico,Argentina,Brazil
Coal has many important uses worldwide. The most significant uses are in electricity generation, steel production, cement manufacturing and as a liquid fuel. Around 6.6 billion tonnes of hard coal were used worldwide last year and 1 billion tonnes of brown coal. Since 2000, global coal consumption has grown faster than any other fuel.
Open-pit mining refers to the exploitation of coal seam exposed after removing the topsoil and rock above the coal (overburden). The coal mining method is customarily called stripping method since the outcrops of coal have been mined and exhausted, it\'s necessary to strip the topsoil and make the coal seam apparent.
Drift mining is used to access a range of minerals like gold, coal, quartz, and zinc. It poses high economical means of recovery than other more invasive types of underground mining that entail digging up through rock. Sub-horizontal and horizontal tunnels excavated the side of a mountain or hill, given the common name of a drift, are normally driven at an incline or just beneath the vein so that gravity may better assist in the carrying of material out of the mine. Once tunnels are driven, they may be utilized for haulage, ventilation, and exploration of further possible mineral or coal seams. Material is normally mined and taken out using long wall mining, mines , flow or room and pillar mining methods and nonstop mining equipment.
Coal Ball Mill machine is an important auxiliary equipment for coal-powder furnace, and it has three methods to crush the coal lump and grind them into powderlike crushing, impacting and grinding. Air swept Coal Ball Mill is the main equipment in cement plant for both drying and grinding of the powders. Compared with the ordinary ball mill, it has advantages of higher capacity, more convenient operation, safer usage, and more reliable performance.
Total Power (KW)
This coal mining project is an open pit mine located in Nigeria, announced by mining company - Western Goldfields - that it has discovered 62,400,000 tonnes of proven reserves of coal deposits worth US$1.2 billion which could be used for the generation of electric power.
Coal provides one of the best alternative sources of energy for Nigeria due to its availability, easy usage and high heat emission. Therefore it's extremely important to choose best suitable coal mining project solution.
We have cooperative with them to provide series of coal mining equipment including coal crushers, coal mills, screening plant,mobile coal crusher,roll crusher and the whole coal processing plant design. The whole project went smoothly and the cooperation will continue.
Chinese SBM is a professional coal preparation plant process designer and coal equipment manufacturer in Shanghai, China. Been located in the commercial center and having worked on this field over 3o years, shibang can design better solution and supply high quality for clients. We have cooperated with clients from over 130 countries, such as India, America, Australia, South Africa, Canada, Malaysia, Dubai, and so on. The fast profit-returning project that are processing will give customer great help with less money but better service.
Coal has an important role to play in meeting the demand for a secure energy supply. Coal is abundant and widespread. It is present in almost every country in the world with commercial mining taking place in over 50. Coal is the most abundant and economical of fossil fuels. At current production levels coal will be available for at least the next 118 years - compared to 46 years for oil and 59 years for gas. Indigenous coal resources enable economic development and can be transformed to guard against import dependence and price shocks.
Coal is also readily available from a wide variety of sources in a well-supplied worldwide market. It can be transported to demand centres quickly, safely and easily by ship and rail. A large number of suppliers are active in the international coal market, ensuring competitive behaviour and efficient functioning. Coal can also be easily stored at power stations and stocks can be drawn on in emergencies. Unlike gaseous, liquid or intermittent renewable sources, coal can be stockpiled at the power station and stocks drawn on to meet demand.
Coal is also an affordable source of energy. Coal prices have historically been lower and more stable than oil and gas prices and it is likely to remain the most affordable fuel for power generation in many developed and industrialising countries for several decades.
Coal-based electricity is well-established and highly reliable. Over 41% of global electricity is currently based on coal. The generation technologies are well-established and technical capacity and human expertise is widespread. Ongoing research activities ensure that this capacity is continually being improved and expanded, facilitating innovation in energy efficiency and environment performance.
Coal can also be used as an alternative to oil. The development of a coal to liquids industry can serve to hedge against oil-related energy security risks. Using domestic coal reserves, or accessing the relatively stable international coal market, can allow countries to minimise their exposure to oil price volatility while providing the liquid fuels needed for economic growth.
Coal processing is necessary in coal usage and supplying right size coal ores for coal industry. Coal processing is also the important coal mining equipment which process coal with crushing, grinding, conveying and screening, etc.
Coal crusher is widely used in the coal crushing process. As technology developed, now we have many types of coal crushers, including jaw crusher, cone crusher, impact crusher and portable crushing and screening plant. SBM supply a whole set of coal crushing production line to coal processing industry.
Coal mill is the most important coal processing plant as coal is usually fed into fire power plant to generate energy. SBM vertical coal mill is the one we designed for coal pulverizing and is featured with high capacity, high efficiency and long service time. Ball mill, hammer mill and other coal grinding equipments are also widely used in cola processing.
Coal screening plant is one kind of coal selecting and purifying equipments. Coal screening plant helps to separate the right size coal granules we need from those not passable. SBM vibrating screen is welcomed during coal crushing and coal grinding process.
Coal belt conveyor acts as the transporting part and joint in coal processing production line and so it is necessary during coal processing. SBM coal belt conveyor is rubber belt conveyor and runs in the circumstance temperature range from -20 to +40. SBM coal belt conveyor can work with both outdoor and downhole operation.
Coal crushing and screening plant is the whole set of coal processing production line, equipped with coal crusher, screening plant, belt conveyor and vibrating feeder. Coal crushing and screening plant is more flexible and more widely used than stationary coal crushers.
coal mill coal mill in cement plant | agico cement equipment
The coal mill grinding system is an important part of the dry process cement manufacturing. In cement plants, we usually adopt the air swept coal mill system or vertical mill system as the pulverized coal preparation system, which is arranged at the cement kiln head or kiln tail to provide fuel for clinker calcination. However, due to the flammable and explosive characteristics of pulverized coal, in the process of its preparation, storage, transportation, and combustion, if not handled properly, spontaneous combustion or explosion may occur at any time and cause heavy losses to enterprises. In order to reduce and prevent the occurrence of accidents and ensure the safe production of cement plants, we should fully consider the unstable factors existing in the design of the coal mill system and take a series of measures to eliminate the potential safety hazards.
Pulverized coal is a tiny particle of coal. Its surface area is much larger than that of coal with the same quality. Therefore, after contact with air, it oxidizes and spontaneously ignites more easily. When the pulverized coal suspended in the air reaches a certain limit, it will form an explosive mixture, which will explode and burn in case of an open fire. Once the pulverized coal in the closed system is burned, the pressure will increase rapidly, and the flame will spray out, causing serious personnel burns. The explosion lower limit density of coal powder is 45g/m3 and the upper limit can reach 2000g/m3.
The density of pulverized coal flue gas in silos and pipelines is high. All we need to do is make sure that they are always in a flow dynamic state to avoid spontaneous combustion and explosion caused by blockage and long term accumulation.
There are two hot air sources for pulverized coal drying, namely kiln tail flue gas and kiln head waste gas. When we take kiln tail flue gas as a drying medium, the oxygen content in flue gas is low, which has the effect of inhibiting pulverized coal combustion. So if the process layout allows, the coal mill should be set near the kiln tail as far as possible.
We also need to strictly control the temperature of the gas-powder mixture at the coal mill exit as reducing the temperature not only ensures the safe and stable operation of the grinding system but also reduces the coking of the burner. Generally, the gas temperature at coal mill inlet is not higher than 400, the outlet gas temperature is lower than 90.
In the case of gas combustion and explosion occur in equipment and silo, the fire extinguishing system can spray CO2 timely to stop the combustion. This system has an automatic type and manual type. The former is connected with a monitoring system. When abnormal occurs, it can eliminate hidden troubles in a timely and effective manner. The CO2 fire extinguishing system of cement plants can cover coal mills, cement separators, hot air pipelines, coal mill dust collectors, and coal silo dust collectors.
AGICO Group is an integrative enterprise group. It is a Chinese company that specialized in manufacturing and exporting cement plants and cement equipment, providing the turnkey project from project design, equipment installation and equipment commissioning to equipment maintenance.
coal mill - an overview | sciencedirect topics
To control the quality of coal being sent to the burners located on the furnace walls. The word quality here means the temperature and fineness of the PF. The set temperature values are dependent on the percentage of volatile matter that exists in the main fuel. The controlled temperature is important for many reasons such as stability of ignition, better grindability of solid fuels, better floating ability of suspended PF particles, etc. However, a temperature more than 65 to 70 is not recommended for various reasons.
Operating data from a coal mill is used to compare the fault detection observer-based method and PCA/PLS models based approach. There are 13 process measurements available representing different temperature, mass flows, pressures, speed etc in the coal mill.
The measurement is not updated, if the variation is less than 1%. The variations of T(t) is in the major part of the operational time inside this interval. Therefore, it is not suitable to be chosen as the predictor variable. However, the variations can be extracted from the TPA(t), which is used to control the temperature of the mill. Therefore, the PLS model is developed with the temperature of the mill as the dependent variable. In addition 6 of the other variables are chosen as regressors since there is barely information in the remainder.
A static PCA model is first developed, which captures around 99% of variations with 5 PCs (see Fig.5), which indicates strong collinearity among regressors. As shown in Fig.6, both Q and T2 statistics (with 95% confidence level) of the static PCA model are noisy, which potentially lead to false alarms. A static PLS model with 2 LVs achieves the minimal PRESS (see Fig.7), which is applied to the test dataset. Fig.8 shows the comparison between process measurement and the static PLS model prediction, together with the 95% confidence level. The process gradually drifts away form the NOC model, which eventually moves beyond the threshold around the sample 150. Due to the noise involved in the prediction signal, the estimation moves in and out the threshold from 110 till 200, when it is clearly out of the confidence level. Both Figs.6 and 8 reveal that static PCA and PLS models may lead to false alarms due to the noisy estimation. In addition, process measurements are commonly auto-correlated, this behavior is expected since the coal mill runs dynamical. Thus, dynamic models are developed by including time lagged process measurements, to address the issue of auto-correlations and reduce the possibility of false alarms due the none modeled dynamics.
Including time lagged terms enhance the NOC model by including historical data. However, time lagged terms also introduce additional noise into the modeling data block. For example, including n+1 time lagged terms might lead to poorer validation performance than the model with n terms due to measurement noise. Therefore, PRESS is used to choose an appropriate number of time lagged terms for a dynamic PLS model.
The predictive ability of the PLS model is improved with the inclusion of time lagged terms. The PRESS decreases from 1.645 to the minimal value of 1.142, which is obtained with a dynamic PLS of 3 LVs using 8 time lagged terms. The application of the dynamic PLS model to the test data reveals that the fault occurs in the process around sample 160. Fig.9 also shows a much smoother prediction such that the possibility of false alarms is significantly reduced. A dynamic PCA model is developed by the inclusion of 8 time lagged terms. The number of PCs is chosen as 2 through cross-validation, which explains 70.6% of process variations. The Q statistic of the dynamic PCA model is shown in Fig.10, the fault is detected around 160 samples, which is consistent with the dynamic PLS model.
The control loop for mill outlet temperature discussed here is mainly for TT boilers based on a CE design with bowl mill (refer to FigureVIII/5.1-2). A similar loop is valid for a ball-and-tube mill, which is discussed separately in the next section. In order to understand the loop in the figure, it is advisable to look at FigureVIII/5.0-1 and the associated PID figure (refer to FigureIII/9.2-4).
The outlet temperature of the coal mill is maintained at desired point so that the coal delivered from the mill is completely dry and achieves the desired temperature. Also, in case of high temperature at the mill outlet, cold air is blown in to reduce the risk of fire.
Normally, the entire requirement of PA flow necessary for a particular load at the mill is initially attempted through HAD so as to ensure complete drying of the coal (especially during rainy seasons) and to raise the mill temperature at a desired point. However, there may be times during hot dry summers when the mill outlet temperature shoots up. This is also never a desired situation because of fire hazard. In fact, to combat this fire hazard, arrangements for mill-inerting systems with inert gases (e.g.,N2 and CO2) need to be made (another purpose is to reduce air supply).
This is more important for ball-and-tube mills, especially when these are operated with one side only. Therefore, CAD comes into operation whenever there is need to bring down the mill temperature. Naturally when this damper operates (i.e., starts opening through process feedback), the hot air damper closes. Here also is a cross-operation of the two dampers but through process and not directly via the loop, so control loop disturbances are fewer than in the old days when cross-operations were implemented in the loop.
Mill outlet temperatures measured by redundant temperature elements and transmitters are put in an error generator. (Temperature element specialties were discussed earlier and so not repeated here.) The output of the error generator drives a PID controller. In general, since temperature is a sluggish parameter it is always advisable to use PID controllers for better results. To prevent controller saturation, controllers are put into service only when both the loops are in auto. The output of the controller through I/P converters normally drives pneumatic actuators meant for CAD.
As stated earlier, only when both HAD and CAD are in auto is the controller put into operation. Since FSSS operations depend on mill temperature conditions, with the help of the limit value monitor (LVM) necessary contacts statuses are shared with FSSS. The loop can be released to auto by an FSSS command. As a protection, both the full opening command and the >x% command for the mill CAD are issued from FSSS so sufficient cold air is circulated. If the auto release command from FSSS is missing or if HAD is in manual, it is necessary to inhibit auto operation so that the operator pay complete attention to the mill outlet temperature. That is the check back signal for FSSS from the loop for damper position.
How breakage energy and force are applied in the mill in order to achieve size reduction in an efficient and effective manner. This is a matter of design and performance of mills and the main subject of this section;
How the material being reduced in size behaves in terms of breakage characteristics such as strength and resulting broken size and shape. This relates to how the material responds to the application of breakage energy and force in terms of rate and orientation of application.
The analysis of individual mill design and operation is complex; so, for simplicity we will consider a typical mill layout for one mill type only. As VSMs have come to represent the bulk of the power station mill fleet, the explanation of mill operations will be based on this mill type. Figure13.2 illustrates the typical key components of a VSM.
In coal milling for power stations, a closed-loop process is used in which the rejects from the classifier are returned to the mill for regrinding. In VSMs, the re-circulation loop is within the mill, but some mill types would have an external loop. In fact, there are a number of re-circulation loops within a mill system. The situation is further complicated by the mill reject streams that reject undesirable material (tramp metal and non-coal bearing rock) from the mill. Generally, the following steps illustrate the path through a VSM:
Air entering through the Port Ring creates a fluidising zone in which heavy material (Mill Rejects) such as rock falls through the Port Ring into the Air Plenum below the Grinding Table and is ejected from the Mill through the Mill Reject System;
From the fluidising zone the ground coal is lifted up inside the Mill Body. Larger particles of coal reach a terminal velocity at which gravity will pull them back on to the Grinding Table for regrinding (Elutriation);
The fineness of the milling product and the capacity of the pulverizer are strictly connected. With increased fineness grows the overall circulation rate of coal in the mill, coal retention time and the flow resistance. As a result, the maximum mill capacity decreases and the rate of change of operational parameters of the furnace system deteriorates. In extreme cases, the performance of the boiler may be limited, and therefore improving the fineness of milling product must often include the modernization of the grinding system. The increase of the throughput of a pulverizer, which compensates the loss of capacity resulting from the increased fineness of coal dust, may be achieved through:
The analysis  proves that the maximum capacity of the ball-ring mill is obtained using 5 or 6 balls. Because earlier, as a rule, a greater number of balls was used, there is a possibility to increase the capacity by replacing the existing balls through a lower number of bigger balls. For example, in the EM-70 of FPM SA 9 balls of the diameter 530mm were replaced with 7 of 650mm. Such a modernized milling system can usually be set up on the existing gearbox. It should be noted that the costs associated with replacement of the classifier and the grinding elements are only slightly greater than the costs of the major repair of the mill. In the case where an existing mill has a grinding unit of the number of balls close to 6, the only way to increase performance is to increase the diameter of the balls, but this requires replacement of the mill body.
It has to be mentioned that the number of balls is increased during the mill operation. For example, the initial ten balls, after lowering the diameter below some value (due to wear), is complemented with the 11th additional ball.
If the existing pulverizer is equipped with 6 or 7 balls, increasing of its capacity is also possible by means of replacing the ball-ring system with the bowl and roller milling device. The milling costs per Mg of fuel in both systems are similar. However, with the same dimensions of the milling systems, the capacity of the roller system is about 15%20% higher. Another advantage is the shorter renovation time, which is about 714days for the ring-ball system, while for the roller mill, only 37days. In addition, hardfacing and re-profiling of grinding components are much easier for roller milling systems.
During the modernization of milling plant with compression mills, detailed analysis requires the selection of cross sections of nozzle-rings at the inlet of the drying agent to the mill, in order to minimize the amount of coal removed from the grinding chamber. The preferred solution is a rotating nozzle ring integrated with the bowl. This ring equalizes air distribution pattern at the periphery of the grinding chamber, which allows increasing the capacity of the grinding system without fear of excessive loss of fuel from the mill.
The rotational speed of the vertical spindle mill affects the operating conditions of the grinding unit. At high rotational speeds, the grinding unit operates at high flow of the material in the radial direction and low layers of the material under the grinding elements (balls, rollers). This causes the particles to be discharged without comminution and increases circulation in the mill. At the same time, the flow resistance and milling energy consumption (including erosive and abrasive wear) of the mill will increase.
If the rotational speed is too low, the material flow will decrease significantly. The thickness of the material layer under grinding elements will exceed the maximal height for which the particles are drawn under the grinding elements, causing excessive buildup of the material in front of the grinding elements. The material outflow from the bowl (or the bottom ring) is not supported by grinding elements movement, which results in higher flow resistance and uneven loading of the nozzle ring. These factors cause a significant decrease in mill efficiency.
Tests carried out for some industrial mills have proven that the change of grinding unit rotational speed strongly influences mill capacity. Therefore, by changing the gear ratio of the mill, both milling capacity and dynamic properties of the mill can be improved.
The fuel injector is designed to introduce the dispersed coal particles in a medium of air into the furnace. The mass ratio of air to coal is dependent on the coal mill manufacturer and usually ranges from 1.75 to 2.2 with a typical value of 2.0. An air to fuel mass ratio of 1.8 produces a primary stoichiometric ratio of approximately 0.16, or 16% of the air necessary for complete combustion of the coal. According to the previous discussion of NOx formation chemistry it is expected that lower NOx concentrations are achievable with lower primary gas/fuel ratios. The diameter of the coal transport line is constrained by the minimum velocity at which coal particles remain entrained in the carrier gas, or the coal layout velocity. This velocity is generally accepted to be 50 ft/s (Wall, 1987). The dimension of the fuel injector itself is selected by the burner manufacturer to provide the desired gas and particle velocity at the exit of the burner. The velocity here is anywhere from 50 to 115 ft/s and is chosen to provide the desired near flame aerodynamics impacting the mixing between the primary and secondary air. In many applications, there is an elbow, scroll or turning head in the coal pipe at the burner inlet. Such inlet devices result in roping, or an uneven distribution of coal within the fuel injector. Many manufacturers use components to redistribute the coal particles with an even density around the circumference of the fuel injector at its exit. A uniform distribution is typically desired to minimize NOx while maximizing combustion efficiency. The material of the fuel injector is chosen to be reliable under high temperatures and erosive conditions and is often a high grade of stainless steel. Another component of the fuel injector that is found on many commercial low NOx burners is a flame stabilizer. The function of this feature is to provide a stagnation zone at the fuel injector exit on the boundary between the primary and secondary air where small-scale mixing of coal and air occurs, providing ideal conditions for ignition and flame attachment.
Sulfur in coal can affect power plant performance in several ways. Sulfur in the form of pyrite (FeS2) can lead to spontaneous combustion and contributes to the abrasion in coal mills; therefore, if a lower quality coal containing pyrite is used in place of the design coal it can lead to problems. As the overall sulfur concentration increases, so do the emissions of sulfur dioxide (SO2) and sulfur trioxide (SO3). While the majority of the sulfur is converted to SO2 (about 12% of the sulfur converts to SO3), the increase in SO3 emissions increases the flue gas dew point temperature, which in turn can lead to corrosion issues. Most countries have legislation restricting SO2 emissions and utilizing higher sulfur coals will require additional SO2 controls (Miller, 2010). In some cases, the use of low quality fuels may impair the desulfurization equipment because of a greater quantity of flue gas to be treated (Carpenter, 1998).
All power stations require at least one CW pump and one 50% electric boiler feed pump available and running to start up a unit. In addition, fossil plant requires either coal mills or oil pumps and draught plant, e.g., FD and ID fans, PA fans, etc. Gas-cooled nuclear plant requires gas circulators running on main motors or pony motors at approximately 15% speed, whereas water reactors require reactor coolant pumps. Both nuclear types require various supporting auxiliaries to be available during the run-up stages, the poor quality steam being dumped until the correct quality is achieved.
When steam of correct quality is being produced, the turbine-generator will be run up to speed with all the unit supporting auxiliaries being powered from the station transformers via the unit/station interconnectors.
The Amer 9 plant utilizes both direct and indirect co-firing configurations. The plant co-fires biomass pellets up to a maximum of 1200ktyr1, generating 27% by heat through two modified coal mills. Only wood-based fuel has been used since 2006, due to reduced subsidies for agricultural by-products.
For the indirect co-firing option, low-quality demolition wood is gasified in a CFB gasifier at atmospheric pressure and a temperature of approximately 850C. The raw fuel gas is cleaned extensively and combusted in a coal boiler via specially designed low-CV gas burners. An advantage of this concept is that there is no contamination of the fuel gas as it enters the coal-fired boiler. This allows a wide range of fuels to be co-fired within existing emission constraints while avoiding problems with ash quality. The challenge, as always, is working within the relatively stringent fuel constraints while avoiding the inevitable high investment costs . Amer 8 also co-fires at high biomass feed levels but uses a standard hammer mill configuration.
Coastal power stations, due to their proximity to major urban areas, tend to be better managed in terms of production consistency and environmental standards. In China and India in particular, coastal power stations tend to mill coal more finely, use superior emissions to control technologies, and have a tendency to use higher-quality coal blends. The result is higher quality and greater consistency in fly ash chemical and physical properties, to the extent that the material is more desirable to local cement manufacturers and those in other domestic markets along the coast. This material is typically allocated in multiyear contracts.
Adding to this, coastal urban areas usually have high volume demand for construction materials. Coastal power stations are often fully contracted to supply cement-grade fly ash, as well as the run of station ash and bottom ash to serve this demand. This is particularly clear in China, where coastal cities such as Shanghai and Shenzhen have seen dramatic urban development over the last 20years. During this period, both cities have been net importers of fly ash, drawing from both inland and domestic coastal sources.
The cost of loading material onto vessels, whether in containers or bulk, is much lower at coastal power stations due to lower local land transport costs. As a result, coastal power stations have been logical first choices for exporters/importers, and many have already developed either domestic coastal markets for their ash or export markets.
coal preparation plant | coal preparation process | coal washing | m&c
Coal preparation plant is a coal processing plant that include a series of processes: raw coal screening, crushing, coal washing, separation, clean coal dewatering and slime recycling. Which can separate coal from impurities, remove mineral impurities from raw coal and divide it into different specifications of products.
Raw coal is mixed with various mineral impurities in the process of formation, and inevitably mixed with rocks and other impurities in the roof and floor in the process of mining and transportation. So the raw coal must be prepared, the main purpose of coal preparation can be summarized as follows:
Crushing & Screening: Raw coal is transported to crushing workshop by belt conveyor. First, it is pre screened by a circular vibrating screen with a sieve opening of 50 mm. +50mm materials and extra large gangue enter the crusher and are crushed to 50mm, and then transported to the coal washing workshop together with -50mm raw coal that under the vibrating screen.
Jig Density Separation: Raw coal in the coal washing workshop is distributed to two raw coal buffers by scraper transporters, and two chain coal feeders are fed into two jigs respectively. Raw coal is divided into clean coal, medium coal and gangue in the jigs.
After the medium coal and gangue are dewatered by the bucket elevator, they enter the medium coal and gangue bunker respectively, and then transported by the automobile as the final products. The clean coal is graded and dewated by a linear vibrating screen with sieve hole of 13mm, and the coal under the screen enters the pit for grading.
Clean Coal Dewatering: The 13-0.5mm clean coal in pit is first dewated by bucket elevator, secondly dewated by centrifuge machine, and then transported to the clean coal storage yard by belt conveyor as the final product together with the clean coal on the screen.
Flotation: The overflow from the pit enters the flotation feed pool and is pumped to the pulp preprocessor through the slurry pump. The foaming agent and collector are added to the pulp preprocessor, and the coal slime water after adding auxiliaries flows into the flotation machine.
-0.5mm slime is separated into clean coal and tailings in the flotation machine. The flotation clean coal flows into the flotation concentrate pool and is pumped to the clean coal filter press for dewatering. The dehydrated flotation clean coal is mixed with jigging clean coal as the final product.
Tailings Concentration: Floation tailings flows into the tailings pool of the concentrator workshop and then pumped to the paste thickener, usually 2 paste thickeners are required to stand by each other to ensure that when an accident occurs in the thickener, the slime water will not be drained out.
Slime Management: The bottom flow of the concentrator(thickener machine) is dehydrated by the filter press, and the filtered slime is transported to outside of the coal preparation plant. The overflow of the concentrator and the filtrate of the filter press flow into the circulating pool in the concentration workshop, which is pumped to the jig for recycling use.
CRF Circulating Water: The water of the whole coal preparation plant needs to be recycled, because the water cost much in a wet coal preparation plant, Usually the repeated utilization rate of water needs to be more than 90%, and the unit supplementary water quantity is less than 0.15m / t (raw coal).
[Coal Washing]: As coal preparation plant is divided into dry preparation and wet preparation, the processes of coal preparation with jig and heavy medium cyclones generally need to use water as the separaton medium, so it is also known as a coal washing plant. While the coal processing with air separation, screen separation or manual separation, etc. that without use of water is called a coal preparation plant or dry coal beneficiation.
Specs- With master meter, output capacity 1 000 ton/hr, feed size 150mm x 150mm or more, max feed height 3600mm, min hoper capacity 8m3, triple deck vibration screen of min size 1520mm x 6100mm, Diesel powered and Coal size output 40mm