Process for jointly preparing super pure coal and ultra-low ash clean coal

Abstract

The present invention discloses a process for jointly preparing ultra-pure coal and ultra-low ash clean coal, which relates to the technical fields of pulverized coal (slurry) separation and purification and ultra-pure coal preparation. Low-ash coal slurry is subjected to primary separation to obtain preliminarily selected clean coal and tail coal; the preliminarily selected clean coal and tail coal are respectively subjected to grinding and thickening; the thickened clean coal and tail coal enter their respective grinding systems, and after the materials after grinding meet the optimal particle size requirements, they respectively enter their respective deep separation systems to separate products with qualified ash content; the respective concentrates and tailings after deep separation enter the thickening and dehydration systems respectively to realize the dehydration and recovery of ultra-pure coal and ultra-low ash clean coal. According to the properties of the coal slurry to be selected, the present invention can simultaneously realize the preparation of ultra-pure coal and ultra-low ash clean coal, and can also flexibly select to separately prepare ultra-pure coal or ultra-low ash clean coal, with good applicability, high recovery rates of ultra-pure coal and ultra-low ash clean coal, high efficiency and energy saving, and remarkable economic benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of pulverized coal (slurry) separation, purification and ultra-clean coal preparation, and particularly relates to a process for jointly preparing ultra-clean coal and ultra-low ash clean coal. Background Art

[0002] With the continuous exploitation of coal, the reserves of high-quality coal resources are decreasing, and coupled with increasingly strict environmental protection requirements, the demand for high-quality coal resources has increased sharply, highlighting the importance of high-value utilization of coal resources. Obtaining coal-based functional materials through coal grading conversion and fine processing is the trend of high-value utilization of coal.

[0003] Ultra-clean coal or ultra-low ash pure coal (there is no strict definition for ultra-clean coal and ultra-low ash clean coal. Here, it is defaulted that ultra-clean coal is clean coal with ash content less than 1%, and ultra-low ash clean coal is clean coal with ash content less than 3%, or less than 5% ash content is also acceptable) as a product of a new technology for clean conversion and grading utilization of coal can not only be prepared into fine coal water slurry, but also be used for coking and the preparation of various coal-based materials. These high-value products have opened up a broader market and can create huge economic value.

[0004] Currently, the main methods for preparing ultra-clean coal or ultra-low ash clean coal include chemical deashing method, oil agglomeration method, triboelectrostatic separation method, selective flocculation method, conventional physical method, etc. In the preparation process of ultra-clean coal (or ultra-low ash clean coal), most methods require that coal and minerals can be fully dissociated before separation. However, it is difficult to prepare ultra-clean coal (or ultra-low ash clean coal) with the existing technology. For fine-grained coal, most of its ash content is determined by clay minerals distributed in a fine-grained form in the organic matter, and its particle size is very fine, which is extremely unfavorable for the preparation of ultra-clean coal and ultra-low ash clean coal. Therefore, it is necessary to strengthen dissociation to fully dissociate the organic matter and inorganic minerals in coal, thereby reducing the ash content of the product.

[0005] The conventional process flow is that the coal sample is directly ground fine, and then after one rough selection and multiple fine selections by a flotation machine (or flotation column), a clean coal product with low ash content is obtained. This process flow is simple, but the energy consumption of grinding is large, the low-ash clean coal is easily contaminated by high-ash fine mud, and the flotation cost is increased. Currently, there are few low-ash coal resources, the coal quality changes greatly, and the structure of low-ash products demanded by the market changes rapidly. How to flexibly, efficiently and energy-savingly prepare ultra-clean coal (or ultra-low ash clean coal) has become a difficult problem in the process of clean and efficient utilization of coal resources. Summary of the Invention

[0006] In order to solve the above technical problems, the present invention provides a process for jointly preparing ultra-clean coal and ultra-low ash clean coal, which has the advantages of strong adaptability, energy-saving and high efficiency, and remarkable economic benefits.

[0007] To achieve this technical purpose, the present invention adopts the following scheme:

[0008] The process for jointly preparing ultra-pure coal and ultra-low ash clean coal is carried out according to the following steps:

[0009] S1. Prepare a slurry with a concentration of 50 - 100 g / L from slime / coal powder, conduct primary separation on the slurry, perform ultra-pure coal separation and preparation on the concentrate after primary separation, and / or perform ultra-low ash clean coal separation and preparation on the tailings after primary separation;

[0010] S2. Fine selection

[0011] (1) Ultra-pure coal preparation: The concentrate obtained from primary separation is subjected to the first concentration, the concentrated material is ground, the ground material is subjected to ultra-pure coal separation, and the concentrate product obtained from ultra-pure coal separation is concentrated and dehydrated, and the dehydrated product is the ultra-pure coal product;

[0012] (2) Ultra-low ash clean coal preparation: The tailings obtained from primary separation are subjected to the first concentration, the concentrated material is ground, the ground material is subjected to ultra-low ash clean coal separation, and the concentrate product obtained from ultra-low ash clean coal separation is concentrated and dehydrated, and the dehydrated product is the ultra-low ash clean coal product.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0014] The slime in the primary separation system is first selected and then subjected to one or more fine selections and then ground, separated and upgraded respectively. Such a design first avoids the mutual interference and pollution caused by the concentrate and tailings during the upgrading process. Secondly, it can flexibly adjust the product structure according to the coal quality situation, reduce the grinding workload, lower the energy consumption, and improve the economic benefits; the concentration operation can, on the one hand, concentrate the material entering the grinding system, and on the other hand, remove a part of the high-ash fine mud to avoid its excessive pulverization and pollution of the clean coal; multi-stage grinding is adopted, and the proportion of the particle size of the grinding discharge less than 0.01 mm is not less than 70%, which ensures the full dissociation of coal and associated minerals and provides a guarantee for selecting ultra-pure coal (ultra-low ash clean coal) in the subsequent separation link; the concentration operation and the concentration and dehydration operation in this solution accelerate the efficient concentration and sedimentation of the finer and less sedimentable particles in the process, improving the production efficiency of the whole system.

[0015] The technological links of ultra-pure coal preparation and ultra-low ash clean coal preparation are basically the same without considering the coal slime water and dilution water, which can ensure that the subsequent treatment links of the concentrate and tailings obtained from the primary selection of coal slime can be shared, that is, the product structure can be flexibly adjusted to adapt to the changes in coal quality and the market; this solution can simultaneously separate 4 kinds of products with different ash content levels, namely ultra-pure coal products, low-ash clean coal products, coal slime products in the clean coal slime concentration system, and coal slime products in the tail coal slime concentration system, or only separate two of the ash content gradient products.

[0016] The preferred solution of the present invention is:

[0017] The overflow water from the first concentration of ultra-clean coal, the tailings obtained from the separation of ultra-clean coal, the overflow water and part of the filtrate generated during the concentration and dehydration of the concentrate product from the separation of ultra-clean coal are returned to the primary separation as dilution water, and the remaining part enters the fine coal slime concentration system.

[0018] The overflow water generated from the concentration of ultra-low ash clean coal is returned to the ultra-low ash clean coal separation process as dilution water. The tailings from the separation of ultra-low ash clean coal and the overflow water and filtrate generated during the concentration and dehydration of the concentrate from the separation of ultra-low ash clean coal enter the tail coal slime concentration system.

[0019] During both the grinding of ultra-clean coal and the separation of ultra-clean coal, clear water is added as makeup water.

[0020] During both the grinding of ultra-low ash clean coal and the separation of ultra-low ash clean coal, recycled water is added as makeup water.

[0021] The primary separation uses a flotation process. The concentrate and tailings after flotation are respectively subjected to concentration and dehydration and grinding operations. The number of flotation times in the primary separation is flexibly adjusted according to the ash content index requirements of the separated products and the coal quality characteristics.

[0022] The feed concentration of the grinding operation is adjusted to the optimum through concentration and addition of dilution water to achieve a better grinding effect. The grinding system is a two-stage grinding, and the number of grinding times can be increased or decreased according to the degree of material dissociation. The particle size of the grinding discharge involved in this process flow all meets the requirement that the proportion of particles smaller than 0.01 mm is greater than or equal to 70%, but is not limited to this. The optimum grinding particle size is selected comprehensively considering the particle size of the disseminated impurities in the coal slime.

[0023] The equipment used for the concentration operation is a sedimentary centrifuge or a hydraulic classification cyclone.

[0024] Both the separation of ultra-clean coal and the separation of ultra-low ash clean coal use a flotation process, and the feed concentration of the flotation process is < 30 g / L.

[0025] When the ash content of the coal slime to be separated is relatively low (lower than 20%) or the product is required to be ultra-clean coal, half of the concentrate from the primary separation system is sent to the preparation process for separating ultra-low ash clean coal. The tailings obtained from the primary separation directly enter the tail coal slime concentration system, doubling the output of ultra-clean coal. When the ash content of the coal slime to be separated is relatively high (higher than 20%) or the product is required to be ultra-low ash clean coal, half of the tailings obtained from the primary separation is sent to the preparation process for separating ultra-clean coal, and the concentrate obtained from the primary separation is directly filtered press as the ultra-low ash clean coal product. Description of the Drawings

[0026] Figure 1 It is the process schematic diagram for jointly preparing ultra-clean coal and ultra-low ash clean coal provided by the embodiment of the present invention;

[0027] Figure 2 It is the process flow diagram for jointly preparing ultra-clean coal and ultra-low ash clean coal provided by the embodiment of the present invention;

[0028] Figure 3 Process flow chart of ultrapure coal preparation provided by the embodiments of the present invention;

[0029] Figure 4 Process flow chart of ultra-low ash clean coal preparation provided by the embodiments of the present invention;

[0030] Figure 5 Specific process flow chart of Embodiment 3 of the present invention;

[0031] Figure 6 Is the step-by-step release flotation curve graph. Specific embodiments

[0032] To fully understand the purpose, features and effects of the present invention, the present invention will be described in detail through the following specific embodiments, but the present invention is not limited thereto.

[0033] Such as Figure 1 As shown, a process for jointly preparing ultrapure coal and ultra-low ash clean coal provided by the present invention is carried out according to the following steps:

[0034] S1. Primary selection: Pulverized coal (slurry) is prepared into a slurry with a concentration of 50-100 g / L, and the slurry is fed into the primary separation process to obtain primary concentrate and primary tailings. The reagents used in primary flotation are common reagents for coal preparation, such as diesel oil and sec-octanol.

[0035] S2. Fine selection:

[0036] Ultrapure coal separation: The primary concentrate enters the ultrapure coal separation process for the first concentration, and after concentration, it enters the ultrapure coal separation grinding operation. After grinding to a particle size of <0.01 mm with a proportion of ≥70%, it enters the ultrapure coal separation operation. The concentrate foam obtained from ultrapure coal separation is concentrated and dehydrated, and the dehydrated product is the ultrapure coal product. Clear water is added as makeup water in both the grinding operation and the ultrapure coal separation operation. Part of the overflow water or tailings from the concentration operation, ultrapure coal separation operation, and concentration and dehydration operation in the ultrapure coal separation process is returned to the primary separation process as dilution water, and the other part enters the clean coal slurry water concentration operation for concentration and recovery.

[0037] Ultra-low ash clean coal separation: The primary tailings enter the ultra-low ash clean coal separation process for the first concentration, and after concentration, it enters the ultra-low ash clean coal separation grinding operation. After grinding to a particle size of <0.01 mm with a proportion of ≥70%, it enters the ultra-low ash clean coal separation operation. The concentrate product obtained from ultra-low ash clean coal separation is concentrated and dehydrated, and the dehydrated product is the ultra-low ash clean coal product. The overflow water from the concentration operation in the ultra-low ash clean coal separation process is returned to the ultra-low ash clean coal separation operation as dilution water. The tailings, overflow water, and filtrate from the grinding operation and the concentration and dehydration operation in the ultra-low ash clean coal separation process are combined and enter the tail coal slurry water concentration operation for concentration and recovery.

[0038] Example 1

[0039] As Figure 2 shown, a process for jointly preparing ultra-clean coal and ultra-low ash clean coal is carried out according to the following steps:

[0040] S1. After the coal powder (slurry) is prepared into a slurry with a concentration of 50 - 100 g / L, it enters the primary roughing flotation machine for primary rough flotation. The concentrate of the primary roughing flotation enters the primary cleaning flotation machine for primary cleaning flotation. The concentrate of the primary cleaning flotation machine enters the first concentration equipment for concentrating the primary cleaning concentrate. The tailings of the primary roughing flotation machine and the primary cleaning flotation machine are combined and then enter the second concentration equipment for concentrating the primary tailings.

[0041] The overflow of the first concentration equipment has two channels. It can either directly enter the clean coal slurry concentration system or return to the primary cleaning flotation machine as dilution water. The underflow of the first concentration equipment enters the concentrate first-stage grinding system.

[0042] S2. The make-up water for the concentrate first-stage grinding system is clear water. After the concentrate first-stage grinding system, it enters the concentrate second-stage grinding system. The discharge of the concentrate second-stage grinding system enters the ultra-clean coal roughing flotation machine for ultra-clean coal rough flotation.

[0043] S2-1. The concentrate of the ultra-clean coal roughing flotation machine enters the first cleaning flotation machine for ultra-clean coal for the first cleaning flotation. The concentrate of the first cleaning flotation machine for ultra-clean coal enters the second cleaning flotation machine for ultra-clean coal for the second cleaning flotation. The concentrate of the second cleaning flotation machine for ultra-clean coal enters the ultra-clean coal concentration equipment for ultra-clean coal concentration. All the tailings of the ultra-clean coal roughing flotation machine, the first cleaning flotation machine for ultra-clean coal, and the second cleaning flotation machine for ultra-clean coal, according to the concentration conditions of the primary cleaning flotation, part of them returns to the primary cleaning flotation machine as dilution water, and the remaining part enters the clean coal slurry concentration system. The make-up dilution water for the ultra-clean coal roughing flotation machine, the first cleaning flotation machine for ultra-clean coal, and the second cleaning flotation machine for ultra-clean coal is all clear water.

[0044] The underflow of the ultra-clean coal concentration equipment enters the first filter press for ultra-clean coal filtration. The filtration product of the first filter press is the ultra-clean coal product. The overflow of the ultra-clean coal concentration equipment and the filtrate of the first filter press, according to the concentration conditions of the primary cleaning flotation machine, partially return to the primary cleaning flotation machine, and the remaining part enters the clean coal slurry concentration system.

[0045] S2-2. The overflow of the second concentration equipment enters the ultra-low ash clean coal roughing flotation machine as make-up dilution water. The underflow of the second concentration equipment enters the tailings first-stage grinding equipment for tailings first-stage grinding.

[0046] The makeup water for the first-stage tailings grinding equipment is recycled water. After the tailings are ground in the first stage, they enter the second-stage tailings grinding equipment for secondary grinding of the tailings, and the discharge from the secondary grinding enters the ultra-low ash clean coal roughing flotation machine for rough flotation of the ultra-low ash clean coal.

[0047] The concentrate of the ultra-low ash clean coal roughing flotation machine enters the first cleaning flotation machine for the ultra-low ash clean coal for the first-stage cleaning flotation. The concentrate of the first cleaning flotation machine for the ultra-low ash clean coal enters the second cleaning flotation machine for the ultra-low ash clean coal for the second-stage cleaning flotation. The concentrate of the second cleaning flotation machine for the ultra-low ash clean coal enters the ultra-low ash clean coal thickening equipment for thickening of the ultra-low ash clean coal. The tailings of the ultra-low ash clean coal roughing flotation machine, the first cleaning flotation machine for the ultra-low ash clean coal, and the second cleaning flotation machine for the ultra-low ash clean coal enter the tail coal slime thickening system. The makeup dilution water for the ultra-low ash clean coal roughing flotation machine, the first cleaning flotation machine for the ultra-low ash clean coal, and the second cleaning flotation machine for the ultra-low ash clean coal is all recycled water.

[0048] The underflow of the ultra-low ash clean coal thickening equipment enters the second filter press for filtering the ultra-low ash clean coal. The filter press product of the second filter press is the ultra-low ash clean coal product. The overflow of the ultra-low ash clean coal thickening equipment and the filtrate of the second filter press enter the tail coal slime thickening system.

[0049] The data results of Example 1 are shown in Table 1. The ultra-pure coal concentrate obtained by the process flow provided by the present invention has an ash content of 0.93% < 1% and a yield of 28.46%. The ash content of the ultra-low ash clean coal concentrate is 2.87% < 3% and the yield is 14.11%.

[0050] Table 1 Data Results of Example 1

[0051] Name Yield / % Ash Content / % Slime 100 20.67 Primary Separation Concentrate 58.13 4.67 Primary Separation Tailings 41.87 42.76 Ultra - Pure Coal Separation Concentrate 28.46 0.93 Ultra - Pure Coal Separation Tailings 29.67 8.19 Ultra - Low Ash Clean Coal Separation Concentrate 14.11 2.87 Ultra - Low Ash Clean Coal Separation Tailings 27.76 63.01

[0052] Example 2

[0053] When the ash content of the raw coal slime to be processed is less than 20% or only ultra-pure coal (ash content < 1%) needs to be separated, half of the concentrate of the primary separation system is sent to the ultra-low ash clean coal preparation system, and the tailings of the primary separation system directly enter the tail coal slime thickening system to double the output of ultra-pure coal. The process flow diagram is as Figure 3 shown.

[0054] Example 3

[0055] When the ash content of the raw coal slime to be processed is higher than 20% or only ultra-low ash clean coal (ash content < 3%) needs to be separated, half of the tailings of the primary separation system are sent to the ultra-pure coal preparation process, and the concentrate of the primary separation system is directly filtered to be the ultra-low ash clean coal product. The process flow is as Figure 4 shown.

[0056] When it is required that the ash content of the ultra-low ash clean coal product < 3%, use Figure 5In the middle process, coal sample preparation is carried out, and the grades and yields of raw materials and products are shown in Table 2 below:

[0057] Table 2 Data results of Example 3

[0058] Name Yield / % Ash Content / % Slime 100 4.52 Primary Separation Concentrate 43.67 1.47 Primary Separation Tailings 56.33 6.59 Ultra - Low Ash Clean Coal Separation Concentrate 36.38 1.58 Ultra - Low Ash Clean Coal Separation Tailings 19.95 15.71 Total of Ultra - Low Ash Clean Coal Products 80.05 1.52

[0059] The theoretical flotation data results obtained by directly performing multiple flotation operations on the same coal sample as in Example 3 are shown in Table 3. According to the cumulative yield and weighted average ash content in Table 3, the distribution release curve of this coal sample is plotted, as Figure 6 shown.

[0060] Table 3 Stepwise release flotation test results of coal sample

[0061]

[0062] (Note: There is a 0.12 difference in the ash content data of the slime in Table 2 and Table 3. This difference is caused by the actual operation process and is within the allowable error range.)

[0063] If this coal sample does not adopt the process provided by the present invention, but through a conventional roughing + multiple cleaning flotation process, from Figure 6 it can be seen that when the ash content of the clean coal is 1.52%, the theoretical clean coal yield is only 51%. The difference in the clean coal yield between the two processes is about 29 percentage points. See Table 4 below:

[0064] Table 4 Data comparison table

[0065]

[0066] Finally, it should be noted that: The above-listed are only the preferred embodiments of the present invention. Of course, those skilled in the art can make modifications and variations to the present invention. If these modifications and variations fall within the scope of the claims of the present invention and its equivalent technologies, they should all be considered as the protection scope of the present invention.

Claims

1. A process for jointly preparing ultra-pure coal and ultra-low ash clean coal, characterized in that, Proceed as follows: S1. Prepare a pulp with a concentration of 50 - 100 g / L from slime / coal powder, and conduct primary separation on the pulp. The concentrate after primary separation is used for the preparation of ultra-clean coal, and / or the tailings after primary separation are used for the preparation of ultra-low ash clean coal; S2. Fine selection (1) Preparation of ultra-clean coal: The concentrate obtained from primary separation is subjected to the first concentration. The concentrated material is ground, and the ground material is subjected to ultra-clean coal separation. The concentrate product obtained from ultra-clean coal separation is concentrated and dewatered, and the dewatered product is the ultra-clean coal product; (2) Preparation of ultra-low ash clean coal: The tailings obtained from primary separation are subjected to the first concentration. The concentrated material is ground, and the ground material is subjected to ultra-low ash clean coal separation. The concentrate product obtained from ultra-low ash clean coal separation is concentrated and dewatered, and the dewatered product is the ultra-low ash clean coal product; The primary separation uses a flotation process, and the concentrate and tailings after flotation are respectively subjected to concentration, dewatering and grinding operations; Both the concentrate and tailings obtained from primary separation are subjected to grinding operations, and the proportion of the part with a particle size less than 0.01 mm in the grinding discharge is greater than or equal to 70%; Both ultra-clean coal separation and ultra-low ash clean coal separation use a flotation process, and the feed concentration of the flotation process < 30 g / L; When the ash content of the incoming slime is less than 20% or the ash content of the required product, ultra-clean coal, is < 1%, half of the concentrate from the primary separation system is sent to the ultra-low ash clean coal separation and preparation process, and the tailings obtained from primary separation directly enter the tailing slime concentration system to double the output of ultra-clean coal; when the ash content of the incoming slime is higher than 20% or the ash content of the required product, ultra-low ash clean coal, is < 3%, half of the tailings obtained from primary separation are sent to the ultra-clean coal separation and preparation process, and the concentrate obtained from primary separation is directly pressure-filtered as the ultra-low ash clean coal product.

2. The process for jointly preparing super-pure coal and ultra-low ash clean coal according to claim 1, characterized in that, The overflow water from the first concentration of ultra-clean coal, the tailings obtained from ultra-clean coal separation, the overflow water and part of the filtrate generated during the concentration and dewatering of the concentrate product of ultra-clean coal separation are returned to the primary separation as dilution water, and the remaining part enters the clean coal slime concentration system.

3. The process for jointly preparing ultra-pure coal and ultra-low ash clean coal according to claim 1, characterized in that, The overflow water generated from the concentration of ultra-low ash clean coal is returned to the ultra-low ash clean coal separation process as dilution water, and the tailings of ultra-low ash clean coal separation, the overflow water and the filtrate generated during the concentration and dewatering of the ultra-low ash clean coal separation concentrate enter the tailing slime concentration system.

4. The process for jointly preparing ultra-pure coal and ultra-low ash clean coal according to claim 1, characterized in that, Clean water is added as makeup water during both ultra-clean coal grinding and ultra-clean coal separation.

5. The process for jointly preparing ultra-pure coal and ultra-low ash clean coal according to claim 1, characterized in that, Circulating water is added as makeup water during both ultra-low ash clean coal grinding and ultra-low ash clean coal separation.

6. The process for jointly preparing super-pure coal and ultra-low ash clean coal according to claim 1, characterized in that, The equipment used for the concentration operation is a settling centrifuge or a hydraulic classification cyclone.

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