Principle and practical range of compound dry coal preparation technology

After the bold innovation and market development of Tangshan Shenzhou Machinery Co., Ltd., in a short period of 7 years, a new type of dry coal preparation plant (workshop) has been built in 377 coal mining enterprises in 24 provinces, municipalities and autonomous regions. We will promote the application of more than 380 sets of various types of composite dry sorting equipment, and the original coal enrollment capacity will reach 110 million tons/year, so that the proportion of composite dry coal preparation in China's coal preparation method will increase rapidly from zero to zero. 16%, and the future growth momentum is faster, has become a strong vitality coal preparation technology, highly valued by the coal industry leaders. The equipment has been exported to the United States, the Philippines and other countries.

Compound dry coal cleaning equipment won the tenth "Chinese New Technology and New Products Expo" Gold Award; the first "Hebei Province outstanding Invention Award"; and by the State Economic and Trade Commission as "National Key New Product"; the coal industry The technical committee rated it as “the top ten scientific and technological achievements of the coal industry in 2002”; it was approved by the State Environmental Protection Administration and listed as “the national key environmental protection practical technology (A) category in 2004”. After many provincial and ministerial level technical appraisals, the technical level Reach international advanced.

1. The significance of developing composite dry coal preparation

1.1 China's coal resources are abundant, and 80% of the country's coal resources (mainly thermal coal) are contained in the western part of the drought and water shortage. The lack of water resources has become a limiting factor in the development and processing of coal in the west. The composite dry coal preparation technology provides a new technical approach for coal processing and utilization for the strategic shift of China's energy base.

1.2 Compound dry coal preparation is an effective and practical technology for removing and reducing sulfur from power coal. It is rapidly popularized and applied for its unique characteristics to meet the needs of coal enterprises in China. It provides a practical way to improve the proportion of power coal candidates in China. A viable coal preparation method.

1.3 Compound dry coal preparation solves the problem of washing and processing of difficult coal. Such as coal slurry water treatment, slime sales, low economic benefits, etc., is an economical and practical thermal coal sorting processing technology.

1.4 The investment in the composite dry coal preparation plant is only 1/5-1/10 of the investment of the same-scale washing and selecting plant, which solves the problem of insufficient funds for coal mining enterprises. It is easily accepted by China's large, medium and small coal mining enterprises and has been rapidly developed.

1.5 Compound dry coal preparation technology solves the problem of sorting and processing of easily muddy coal (such as lignite) which is not suitable for washing. Many coal mines have used composite dry coal to replace the original jigging coal preparation plant.

1.6 The composite dry coal preparation product has low water content, which solves the problem of reducing the calorific value of commercial coal due to the increase of product moisture due to the washing process of thermal coal. It can also solve the problem of freezing of winter washing products in severe cold areas.

1.7 Compound dry coal preparation technology has been expanding its application range in existing coal preparation plants. The existing coal preparation plant can pre-exil the vermiculite and coal powder, reduce the processing cost of the coal preparation plant and the treatment volume of the slime water, such as the Pinggou Coal Preparation Plant of Haitang Bay Mining Bureau; the lower limit of the existing sorting size can be 25 mm or The 13 mm thermal coal preparation plant plays a complementary and supporting role in sorting and processing the unsorted coal, such as the Yangquan Mining Bureau Minmetals Coal Preparation Plant; it can recycle existing coal gangue, such as Panjiao Group Clean Coal Company; can be used for waste washing and processing of existing coal preparation plants, such as the dry selection workshop of Ningxia Taixi Coal Washing Plant.

1.8 Compound dry coal preparation can be used as the primary link of power coal blending production line. Pre-excavation of impurities such as vermiculite and pyrite before coal blending, reduce coal blending of high-quality coal and improve economic benefits. Such as Shanxi Heshun County Gu Yao Coal Company.

1.9 The composite dry coal preparation technology has broken through the traditional foreign wind power coal preparation (wind jigging, wind shaker, etc.) mode, and adopted a number of new sorting principles to improve the sorting precision and make the wind coal preparation technology on the verge of elimination. Gaining new developments has promoted scientific and technological progress. To make China's wind power coal selection reach the international advanced level.

2 structure, principle and innovation

2.1 Structure of the composite dry sorter

The composite dry sorting machine adopts the self-generated medium (fine coal contained in the raw coal) and air to form a gas-solid two-phase mixed medium sorting; the mechanical vibration is used to make the sorting material spirally inverting to form multiple sorting; full utilization The buoyancy effect of the particle interaction produced by the gradually increasing bed density is sorted. According to this general idea, the corresponding structural design was made for the shape of the bed surface, the vibration form, the material movement track, the bed thickness control, the wind distribution, the air volume control, the bed surface angle adjustment, and the wind and dust removal process. A new type of composite dry sorting machine, the structure of which is shown in Figure 1.

The composite dry sorting machine is composed of a sorting bed, a vibrator, a wind chamber, a rack and a hanging device.

The sorting bed is composed of a bed surface, a back plate, a grid strip, and a discharge baffle. There is a wind chamber under the bed surface that can control the air volume. The air is supplied by the centrifugal fan, and the air flow acts on the sorting material through the air hole on the bed surface. The sorting bed and the vibrator are suspended on the frame by the hanging device, and the longitudinal and lateral angles of the sorting bed can be arbitrarily adjusted.

2.2 Sorting principle

2.2.1 Sorting of materials in spiral motion

The selected material is sent from the feeder to the feed port of the sorting bed to form a bed having a certain thickness on the bed surface. The lowermost layer of ore directly contacts the vibrating and moving bed surface, and the inertial force generated by the vibration of the bed surface causes the lower layer of ore particles to move from the discharge baffle to the back plate, and the material is guided upward due to the blockage of the back plate. The upper layer material is subjected to the thrust and gravity of the backing plate, and slides along the surface layer to the discharge side, forming a velocity gradient in the forward and reverse directions above and below the entire material layer. The coal with the lowest density in the uppermost layer is first peeled off through the discharge baffle, and the remaining materials continue to be cycled in the next cycle. as shown in picture 2.

Due to the vibrational force and the material pressure continuously entering the sorting bed, the continuously turning material forms an approximately spiral motion and moves toward the vermiculite end. Bed width gradually due to reduction, a relatively low density of the upper coal continue to discharge until the final discharge high density and pyrite gangue. On the one hand, the role of wind force strengthens the looseness of the grain group, on the other hand, it forms a gas-solid two-phase mixed medium with fine coal, which improves the precision of sorting.

2.2.2 Sorting effect of authigenic medium

The traditional wind jig has a feed size ratio of 2.5:1 and an upper particle size of 20 mm, while the composite dry sorter has a feed size of 80 to 0 mm, which greatly exceeds the feed size range of the wind jig. Above the surface of the dry selection machine, a gas-solid two-phase mixed medium is composed of fine material and air to form a gas-solid suspension with a certain density and relatively stable. When the material passes through the suspension, the low density coal floats and the high density vermiculite sinks. As the sorting process proceeds, fine-grained pulverized coal is continuously discharged with large-size fine coal, and the remaining coarse particle size is coarser. The medium-density particles with higher density form a new denser gas-solid suspension with air. Conducive to the separation of Chinese coal and vermiculite.

2.2.3 The combined effect of segregation and wind action

The loose and layered material on the surface of the composite dry sorting machine is realized by the combined action of mechanical vibration and updraft. The loose strength increases with the increase of mechanical vibration strength and wind speed.

According to the second law of thermodynamics, any system tends to reduce free energy. The potential energy of the bed before stratification is higher than the potential energy after stratification. As long as the appropriate loose conditions are given, the heavy minerals will enter the lower layer, and the stratification is the process of reducing the potential energy by redistribution of different density ore particles. If the vibration is loose only, it will inevitably cause the "segregation stratification" of the ore group, and the small particles with small density will be squeezed into the upper layer, and the fine coal with a small density will leak to the bottom layer, failing to stratify by density. If there is only wind force, the fine material can only be blown to the upper layer and cannot be layered by density. Only under the combined effect of wind and vibration can the material be stratified by density. As shown in Figure 3.

2.2.4 Buoyancy effect caused by particle interaction of high-density materials

The composite dry sorter naturally forms a vermiculite bed at the bottom of the bed during the sorting process. The vermiculite particles of different particle sizes collide with each other under vibration to produce a buoyancy effect. As the vermiculite layer moves toward the vermiculite end, the low-density coal particles continue to float out of the vermiculite layer, thereby purifying the vermiculite product. In order to strengthen this process, the composite dry sorter is equipped with an adjustable smectite door. In the case of a small amount of raw coal containing strontium, the vermiculite can be formed before the discharge to prevent the coal particles from mixing and improve the purity of the vermiculite product.

2.3 Structure of composite dry coal preparation system

The composite dry coal preparation system includes a feeding portion, a sorting portion, a wind and dust removing portion, an electric control portion, and a product conveying portion.

2.4 Innovation and development of composite dry coal preparation

The composite dry coal preparation breaks through the traditional wind power coal selection mode at home and abroad, and creates a new dry coal preparation equipment with unique separation principle. The main innovations or creative contributions compared to traditional selection are as follows:

2.4.1 The composite dry sorter adopts the gas-solid two-phase mixed medium containing the fine coal (self-generated medium) and the air contained in the raw coal, instead of using the air as the sorting medium, so the sorting material has a wide particle size range. It can reach 80-0 mm, while the traditional wind selection can only sort the narrow size.

2.4.2 Composite dry coal preparation can be used to measure the sorting effect by conventional gravity coal selection index, possible deviation Ep=0.20, imperfection degree: 0.1, quantity efficiency 11=95%, sorting particle size lower limit 3 mm, unit area treatment The capacity is 10 t/h·m2. Greatly better than traditional wind selection.

2.4.3 Composite dry sorting machine uses mechanical vibration to make the material spiral motion. In the process of multiple cycles, the sorting materials are subjected to multiple sorting, which can produce a variety of products with low to high ash content. Re-selection to ensure the quality of clean coal and vermiculite.

2.4.4 The required air volume of the composite dry sorter is only used for the loose bed layer and the mixed medium with fine coal. It does not need to suspend the material, and the air volume is only 1/3 of the traditional wind selection, so the scale of the dust removal system is also greatly reduced. small.

2.4.5 The composite dry sorting machine makes full use of the buoyancy effect generated by the interaction of high-density particles, which can improve the purity of the discharged vermiculite and reduce the particle size of the discharged vermiculite.

3 FGX series composite dry coal preparation equipment product development and technical characteristics

3.1 Product Development

Tangshan Shenzhou Machinery Co., Ltd. organized relevant experts and technicians to continuously improve and innovate small equipment, and developed 12 kinds of composite dry sorter series products suitable for large, medium and small coal mine applications. All products They have been successfully applied in various types of coal mines, and have obtained five national patents and one international patent, and have independent intellectual property rights.

In the process of new product development, the company continuously draws feedback and suggestions from users, continuously improves equipment performance and broadens the application range of dry sorter. The new product development of the composite dry sorter can be classified as follows:

3.1.1 Developed according to the production capacity: FGX-1, FGX-2, FGX-3, FGX-6A, FGX-6, FGX-12A, FGX-9, FGX-18A, FGX-12, FGX-24A , FGX-24 type, FGX-48A type. Production capacity is 10 t/h, 20 t/h, 30 t/h, 60 t/h, 90 t/h, 120 t/h, 180 t/h, 240 t/h, 480 t/h

3.1.2 has been developed according to the structure: single type, combined type, lower vibration type, mobile type. Multi-layer type and re-selection type are being developed.

3.1.3 has been developed according to the use: lump coal type, coal blending type, final coal type, coal gangue type, slag type. We are developing waste sorting and sorting machines, and waste metal sheet metal recycling and sorting machines.

3.2 Technical characteristics of FGX series composite dry sorter (see Table 1)

4 sorting effect of composite dry coal preparation

Compound dry coal preparation is suitable for thermal coal drainage, which not only reduces commercial coal ash, improves coal heat generation, but also avoids the disadvantages of wet coal preparation to increase product moisture; it can also be used for inorganic sulfur as the main sulfur content. Sulfur coal, remove more than 2 mm of granular, massive pyrite and tuberculosis, continuous organisms, etc., in order to reduce the sulfur content of commercial coal to ensure the quality of commercial coal is stable.

5 Factors affecting the effect of composite dry coal separation

The factors affecting the effect of composite dry coal separation are three kinds of raw coal properties, operational factors and user requirements for coal quality.

5.1 Selected raw coal properties

5.1.1 The external moisture (or surface moisture) of raw coal has a greater impact on dry selection, while the internal moisture has little effect. When the external moisture is too high, the viscosity of the selected material particles increases, making it difficult to separate the coal and vermiculite with smaller particle size, especially when the raw coal contains more muddy shale and clay minerals. In the industrial test of composite dry coal preparation, the effect of different external moisture on the sorting effect was tested with Lingxin mine raw coal. The results are shown in Table 5, and the relationship is shown in Fig. 7.

From the test results, it is seen:

1 In the case of less raw coal argillaceous rock, the increase of external coal moisture will increase the clean coal ash and the ash content of the vermiculite product will decrease, indicating that the pollution of small-sized vermiculite and coal will increase.

2 When the external coal moisture <6%, it has no effect on the sorting effect. When the external water is >10%, the sorting effect is obviously deteriorated. Therefore, it is required to dry the external moisture <9%, preferably <7%.

5.1.2 Raw coal particle size

The composite dry sorter is suitable for sorting raw coal with a particle size of 80-0 mm, including coal blends of 50, 25, and 13 mm. The lower limit of the particle size is 3 mill. If the pre-selection classification is adopted, the 6~0 mm pulverized coal will be separately sorted, the diameter of the bed surface vent hole can be appropriately adjusted, and the air volume can be reduced, and a better sorting effect can be obtained, and the lower limit of the sorting granularity can be reduced to <3 mm.

5.1.3 Optionality of raw coal and strontium content

Compound dry coal preparation is suitable for power coal drainage. According to the test results of raw coal floating and sinking, coal and vermiculite are generally demarcated according to the density of 1.8 kg/L. Therefore, when the sorting density is 1.8, the selection of raw coal is difficult according to the method of sorting density δ±0.1%. Most of the raw coal in China is δ1. 8±0.1% content ≤10% belongs to easy coal. The composite dry coal preparation is used as the thermal coal drainage, and the sorting density is 1.8-2.1 kg/L, so that the sorting effect can be achieved well, and the purity of the discharged vermiculite is high.

The higher the strontium content in the raw coal, the lower the internal ash content of the coal, and the more effective the dry selection effect. Nowadays, composite dry coal preparation has been widely used for the separation of coal gangue and washing, and the recovery of low calorific value coal in coal gangue for meteorite power generation.

5.2 User requirements for product quality

The purpose of dry coal preparation is to improve the quality of commercial coal and meet the requirements of users. User requirements are as follows:

1 Eliminate the vermiculite in the raw coal, reduce the ash content of the commercial coal, and increase the calorific value of the commercial coal. The less coal contained in the meteorite products required to be discharged is as good as possible, and the quality of commercial coal meets the requirements of users;

Part 2 excludes pyrite sulfur of medium and high sulfur coal, and reduces sulfur content of commercial coal;

3 Recover coal from inferior coal and coal gangue, improve the economic benefits of the enterprise, and reduce the environmental pollution caused by spontaneous combustion of coal gangue;

4 Supporting coking coal preparation plant, pre-discharged vermiculite and part of dust do not enter the coal preparation plant to reduce coal preparation cost and reduce the burden of coal slurry treatment; and supporting with the coal-fired coal preparation plant to achieve the unwashed and processed final coal Dry sorting processing.

According to the requirements of different users on product quality, adjust the operating factors and structural parameters of the dry sorter to meet user requirements.

6 Scope and characteristics of composite dry coal preparation

6.1 Scope of application

1) Suitable for coal sorting and processing in dry and water-deficient coal producing areas in China, requiring raw coal external moisture <9% and selected raw coal particle size <80mm.

2) Raw coal suitable for use as thermal coal excludes vermiculite, reduces commercial coal ash and increases calorific value.

3) It is suitable for the sorting of easy-to-sludge coal such as lignite and easy to select coal.

4) It is suitable for high-sulfur coal to remove granular and massive yellow iron sulfur and reduce the sulfur content of commercial coal.

5) Suitable for coal transportation stations, coal-fired power plants, gas plants and other enterprises as a reliable means to ensure the quality of coal.

6) It is suitable for the recovery of low calorific value coal of inferior coal and coal gangue.

7) It is suitable for the thermal coal preparation plant with a lower limit of 25 and 13 mm for the final coal sorting and supplementary means.

8) It is suitable for the primary part of coal blending production line and coal preparation plant for pre-discharging, reducing costs and improving economic benefits.

9) Suitable for metal and slag recovery metals and useful materials.

10) Suitable for comprehensive treatment of municipal solid waste classification.

6.2 Characteristics of composite dry coal preparation

1) No water use For dry and water-deficient areas and cold winter areas, dry coal preparation has special significance.

2) Less investment

The coal preparation process is simple and does not require the construction of a factory. A full set of FGX-6 composite dry coal preparation system with a production capacity of 60 t/h and an investment of only over 500,000 yuan, while the same scale 300 kt/a coal preparation plant has invested more than 5 million yuan. The dry selection investment is 1/5 to 1/10 of the water selection investment.

3) Low production cost

The average processing fee for tons of raw coal is 2 yuan, while the cost of jigging coal preparation is 6-8 yuan/ton. Dry selection is 1/3 to 1/4 of water selection.

4) High labor productivity

The number of people employed is small, and the number of operators in the dry selection system is 2-3, and the labor productivity is as high as 80-250 tons/work. The larger the dry selection equipment, the higher the labor productivity.

5) High recovery rate of commercial coal

No coal slurry is produced, and all the commercial coal after the removal of the vermiculite is recovered, and the coal dust collected by the dust removal system is also completely recovered.

6) Low coal moisture after selection

Dry selection does not increase moisture, and wind has a certain dehydration effect on the surface moisture of coal. It can reduce the influence of moisture in commercial coal on calorific value.

7) A variety of products with different ash content

It is conducive to the dry coal preparation operators to meet the different quality requirements of commercial coal users and achieve the maximum economic benefits.

8) Strong adaptability

The lignite, bituminous coal and anthracite coals are used as the thermal coal sorting process to eliminate vermiculite, which has good sorting effect. The feed particle size range is wide, and the composite dry selection system that has been put into production and application has a variety of particle sizes. Coal blending (80～0mm, 50～0mm, 25～0mm), lump coal (70-30 mm, 50-25 mm), final coal (25～0 mm, 13-0 mm) and pre-selection screening After the coal, pulverized coal (80 ~ 13 mm, 50-6 mm) was selected. The dry selection system can be flexibly placed in a narrow site. Suitable for technical transformation of coal enterprises.

9) Good dust removal effect

A side-by-side dust removal process and negative pressure operation are used to ensure that the atmospheric environment and working environment are free from dust pollution. The dust content of some of the discharged gases is <50 mg/m3, which is much lower than the national exhaust emission standard of 150 ms/m3.

10) A small set of FGX-12 dry sorting system (equivalent to 600 kt/a coal preparation plant) covers less than 300 m2.

11) Short construction period and fast production

The composite dry selection system is a steel structure and an assembly coal preparation plant. The user only needs to lay a piece of cement floor according to the basic layout drawing, and then the equipment can be put into production. The construction period is generally half a month to one month.

12) The equipment runs smoothly, the maintenance is small, and the operation is simple.

Dry sorters do not have complex and fragile transmission components. The trouble-free operation of the vibration motor guarantees 10,000 hours.

7 composite dry coal preparation application classification

7.1 Classification by production capacity

The FGX series of composite dry sorters are divided into 12 specifications according to their production capacity. See Table 2 for their technical characteristics. Applicable to large, medium and small coal enterprises of various scales.

7.2 Classification by purpose

FGX series composite dry coal preparation equipment has been widely applied in the country. According to the different requirements of users, the use of composite dry coal preparation can be divided into six types.

(1) Dynamic coal sorting

This is the most widely used. The type of pan. The coal coal quality of coal enterprises is not good enough to meet the coal quality requirements of thermal coal users. It is necessary to remove the vermiculite from raw coal, reduce the ash and sulfur content of commercial coal, increase the calorific value of commercial coal, and improve the economy of coal enterprises. benefit.

This type of application, the original coal quality is poor. Generally, the raw coal ash is 30-50%, and the raw coal contains 10-30%. After dry-selection processing, the commercial coal ash content is reduced by 6 to 15%, and the average reduction is about 10%. The calorific value is increased by 400-1500 kcal/kg, with an average of 800 kcal/kg. Dry selection can discharge 90% of the amount of vermiculite.

(2) High sulfur coal desulfurization

The composite dry sorting machine can remove particles such as pyrite nodules and continuum from 2 mm or more of monomer dissociated. For raw coal mainly composed of pyrite sulfur, if the dissociation is better, the desulfurization rate can reach 60-70%, and the sulfur content drops by about one percentage point. For example, Shanxi Huozhou Mining Bureau Caocun mine produces 900 kt/a of coal, of which 10# high-sulfur coal accounts for 40%. The sulfur content of the selected high-sulfur coal mainly accounts for 62% of organic sulfur, 33% of pyrite sulfur and 5% of sulfate sulfur. After sorting by composite dry sorter, the sulfur content is reduced from 3.65% to 2.67%, 0.98%, the desulfurization rate is 26.85%, and the sulfur desulfurization rate of pyrite is as high as 81.36%, which is basically removed from high sulfur coal. Pyrite. After mixing with the 2# low-sulfur coal of this mine, the sulfur content is stable below 1%.

(3) Sorting of inferior coal (gangue)

Composite dry coal preparation is characterized by its use of non-use water, low investment, low processing cost, and movable. It is of special significance for the classification of low-quality coal and the recovery of coal from coal gangue. For example, the Ningmei Group Taixi Coal Washing Plant uses a FGX-6 hybrid dry selection system to recover low calorific value coal for coal gangue power plant. Panzhihua Coal Industry Group has achieved good economic and social benefits by using a set of FGX-12 equipment to sort coal gangue.

(4) Improve the quality of coal by dry selection and new coal blending technology

The thermal coal blending technology has been included in the “10th Five-Year Plan” of the coal industry as a clean coal technology suitable for China's national conditions. The new technology combining the combined dry coal preparation technology and the power coal blending technology has broad application prospects. As the primary link of the power blending production line, pre-excluding the impurities of vermiculite and pyrite before coal blending and reducing the coal blending volume of high-quality coal can produce significant economic and social benefits.

For example, in Shanxi Heshun County, the composite dry sorter used in the coal blending production line to do the primary part of the raw coal purification operation, and achieved good results.

(5) Application of compound dry coal preparation and coal preparation plant

1) As a thermal coal preparation plant, the set of sorting equipment

The production scale of Minquan Coal Industry Group Minmetals is 4000 kt/a, supporting 4000 kt/a coal preparation plant, and sorting 50~13 mm anthracite. Thanks to 13. The 0 mm grade coal was not washed and the quality was unstable, which led to difficulties in the sale of coal at the end of the mine and the coal at the end of the inventory reached 400 kt. Application in October 1999

The combined dry sorter separates the raw coal, and the ash is reduced from 26.55 to 30.86% to 20.99-21.44%, achieving significant economic benefits.

2) As the main equipment for the pre-discharge process of coking coal preparation plant

Shenhua Group Haitang Bay Mining Company Pinggou Coal Mine Coal Preparation Plant has a scale of 1200 kt/a. There are jigging, heavy media, and flotation processes. However, due to the large amount of raw coal, the concentration of coal slurry is high, and the cost of coal preparation is high. After many arguments, it was decided to use a large-scale composite dry sorter to pre-treat the raw coal in the coal preparation plant. Its advantages:

1 Excluding a large amount of meteorites with a small processing fee, not entering the coal preparation system, reducing the cost of coal preparation.

2 Pre-exclude part of -0.5 mm coal dust, do not enter the coal slurry water system of the coal preparation plant, reduce the washing water concentration and improve the sorting effect.

3 Relatively increased the ability of the coal preparation plant. The annual output of raw coal (including vermiculite) in Pinggou Mine has reached 1500 kt/a, and a higher investment is required if the coal preparation plant is expanded.

3) Replace the easy mud coal preparation plant with a composite dry selection system

The Pingmiao Mining Bureau Hongmiao Coal Preparation Plant is a thermal coal preparation plant for sorting lignite. Due to the serious mudstone mud, the treatment of coal slurry water is difficult and the separation is deteriorated. In December 2001, the FGX-12A composite dry selection system was used to solve the problem of coal preparation for many years. Dry selection system

Installed on the roof of the coal preparation building, making full use of the raw coal and product transportation, coal storage and loading system of the original coal preparation plant. Reduced investment in dry selection plants.

(6) Purification of coal into coal chemical enterprises (coking, gas production)

Datong Coal Mine Group Corporation Gas Plant is a new coal chemical enterprise. The main products are gas, iron alloy special coke, coal tar series, activated carbon series and insulation materials. Using the weakly cohesive coal of No. 2 in Datong area for dry distillation gas production, the products are mainly gas and coke . However, the problem of high coal ash content and high sulfur content has long been plagued by normal production. After using the composite dry sorter to purify the coal, significant results have been achieved. The outstanding performance is: the gas quality is stable, the I-12S content reaches the process standard, and it is widely praised by the gas users. The quality of coke has been greatly improved, and the ash has been reduced from 13% to less than 8%. Cokes of 10 to 25 mm and 25 to 50 mm have been listed as exempt from inspection products in Tianjin Port, and some have been exported abroad. A very good economic benefit has been achieved. Freed a large number of hand-selected workers with high-intensity labor, reduced operating costs, and saved a lot of expensive desulfurizers. The annual economic benefit is 5.25 million yuan.

(7) Liberation of coal mine productivity. After the FGX-12 hybrid dry selection system is used in the Dahebian Mine of Shuicheng Mining Group, the C605 high-sulfur coal seam and C101 high-ash coal seam in the mine are sorted and processed, which not only prolongs the service life of the mine, but also makes the layout of the mining face more Reasonable, greatly improved mine production efficiency, and thus the economic benefits reached 18.13 million yuan / a. The six mines affiliated to the Xinjiang Urumqi Mining Group have stopped mining due to more than 20% ash, causing huge losses. After the compound dry selection, the production capacity of the new mine group will be liberated.

7.3 Classification by user

With the expansion of the application scope of composite dry coal preparation, the types of different users (enterprises) are gradually increasing. In addition to the most widely used coal mining enterprises, coal-based coal transportation stations, coal preparation plants, coking plants, coking gas plants, power plants, coal blending plants and exports have begun to apply composite dry coal preparation as a coal deep processing to improve coal quality. The technology has achieved good results.

Recently, due to the increase in the application of large coal mining enterprises, various coal mine design institutes have also begun to intervene in the design of composite dry selection plants. Such as Yangquan Coal Group Kaiyuan Mining Company Dry Selection Plant (600 kt/a) was designed by Shenyang Coal Mine Design Institute; Taiyuan Coal Gasification Company Jiale Spring Mine Dry Selection Plant (800 kt/a) was designed by Taiyuan Coal Mine Design Institute; Shenhua Group The coal-fired company's dry-selection plant was designed by Datong Coal Mine Design Institute; Yima Coal Industry Group Changcun Mine Dry-Selection Plant (1800 kt/a) was designed by Pingdingshan Coal Preparation Design Institute. With the cooperation of the design institute, the coal preparation system of the compound dry selection plant will be more formal and more perfect.

8 Economic and social benefits of composite dry coal preparation

8.1 Comparison of main economic and technical indicators for composite dry coal preparation

By the end of 2002, the country's raw coal washing capacity is expected to reach 600 million tons, ranking first in the world. It has formed a variety of types of large, medium and small, combined with coking coal and thermal coal, jigging process and heavy medium process and dry coal preparation process. Form a set of coal preparation methods and processes suitable for China's coal characteristics and product requirements.

At present, the design process, construction materials and management level of China's washing and sorting plant are 20 years behind the international advanced level, and the economic and technical indicators are poor. However, the composite dry coal preparation for thermal coal drainage is unique. The following table lists the indicators.

8.2 Actual investment and economic benefits of composite dry coal preparation enterprises

According to the feedback information and application certificate of some application units, the investment situation and economic benefits of some new composite dry coal preparation plants (shops) of the same scale are listed in Table 7. Due to different construction conditions, process flow and user requirements, investment The situation is quite different, but the payback period is no more than one year.

8.3 Social Benefits of Compound Dry Coal Preparation

(1) Drainage efficiency. Compound dry coal preparation can remove 90% of meteorite impurities in raw coal. According to the current operation of more than 380 (sets) sets of dry selection systems, the annual processing capacity of raw coal is 110 million tons. If the average coal content is 15%, and the average transportation distance is 650 km, the transportation capacity can be saved to 10725 Mt.km. The emission of meteorites at the pits can reduce the pressure on urban waste discharge.

(2) Desulfurization benefits

The composite dry coal preparation can remove pyrite from 2 mm or more. For medium and high sulfur coal mainly composed of pyrite, the desulfurization rate can reach 60%. According to the statistics of the high-sulfur raw coal composite dry-cleaning plant that has been put into operation, the annual treatment of raw coal is 10 Mt, and the average sulfur content is reduced by 0.8%, which can reduce the SO2 emission in coal combustion by 160 kt.

(3) Water saving benefits

In general, the washing method of coal washing consumes 0.2 m 3 of coal per ton of coal. According to the current annual dry selection of 110 million tons, water conservation is saved by 22 million tons. In the wash, if the treatment of the slime water is not perfect, the flow will cause serious environmental pollution.

(4) Energy efficiency

The power consumption of the combined dry coal preparation is 2.4 kW·h, and the power consumption per ton of coal in the general coal preparation plant is 3.3-7.6 kW·h. If the average coal consumption per ton is 5 kW·h, the dry coal is 2.6. kW·h, the annual electricity saving is 2.86 X 108 kW·h (according to the current dry selection year, the processing capacity of raw coal is 110 million tons).

(5) Power plant benefits

Commercial coal after dry selection can improve the thermal efficiency of coal-fired boilers. Under the same load, the coal consumption of power generation can be reduced by 5~10 g/kW·h; after the selection, the coal can also make the boiler burn stably; after the meteorite and pyrite in the coal are discharged, the grindability of the coal is improved, and the coal grinding can be reduced. Electromechanical consumption and equipment wear; after the removal of pyrite, the raw coal sulfur is reduced, which can reduce the severe corrosion of the low-temperature heating surface of the boiler by the sulfuric acid vapor; the dry-selected processing coal can also avoid the high heat loss caused by the washing of the thermal coal. Problem (Generally, coal needs to consume 2520 kJ of heat to evaporate 1 kg of water).

It can be seen that the widespread application of composite dry coal preparation has great social benefits.

9 conclusion

(1) FGX series composite dry coal preparation system has broken through the traditional wind power coal selection mode at home and abroad, and created a new coal preparation method with unique separation principle. It is used to process 80-0 mm granular grade raw coal with imperfection degree I=0.11 and quantity efficiency >90%.

(2) FGX series composite dry coal preparation system has no water, low investment, simple process, low production cost, low energy consumption, less environmental pollution, small floor space, short construction period and reliable equipment operation. The advantages of the series. It is in full compliance with national policies on water conservation, energy conservation, comprehensive utilization of resources, and clean coal.

(3) FGX series composite type coal preparation system has successfully applied more than 380 sets (sets) at home and abroad, with a production capacity of 11,000 tons/year (as of June 2004), and achieved significant economic benefits. Social benefits.

(4) The composite dry coal preparation system still needs continuous improvement in the process of mass promotion and application, continuous improvement, and development to depth and breadth. Continue to develop in the direction of large-scale, automation, and multi-purpose to meet the different needs of users at home and abroad.

Conclusion: Under the successful guidance of the composite dry coal preparation technology, in a short period of time, 377 coal mining enterprises in most provinces, municipalities and autonomous regions in China have built a new type of dry coal washing plant, making the composite dry coal washing technology deep. Rooted in the first line of coal enterprises, it has become a dynamic coal preparation technology that has a strong vitality and is well received by local coal preparation plants.

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