A method for harmless treatment and resource utilization of sulfur-containing coal gangue

Abstract

The present invention specifically relates to a harmless treatment and resource utilization method of sulfur-containing coal gangue, belongs to the field of solid waste management technology, and what needs to be solved is the problem that sulfur-containing coal gangue solid waste management is difficult. The technical scheme adopted is: a harmless treatment and resource utilization method of sulfur-containing coal gangue, including the following steps: the first step is to enrich sulfur-containing coal gangue; the second step is to crush the pyrite-enriched gangue to 5-10mm coal gangue fine particles, and sort the pyrite; the third step is to crush the pyrite product to less than 2mm as sulfur sand, and mix it with fine-grained pyrite ore as a pyrite product. It can be used to prepare iron powder and sulfur, and it can also be sold separately as a raw material for preparing sulfuric acid. The present invention is used for pyrite enrichment and sorting of sulfur-containing coal gangue with a sulfur content of 3% to 10%, which can achieve a thorough management of solid waste and greatly reduce resource and energy consumption.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste treatment, and in particular relates to a method for harmless treatment of sulfur-containing coal gangue and resource utilization. Background Art

[0002] Gangue is a carbon-containing rock produced during the process of development and excavation, coal mining, and washing. Gangue treatment generally adopts traditional stacking and landfilling methods. 90% of gangue treatment is handled by covering with loess. In mountainous areas, gangue is used to fill gullies, layered rolling, surface soil, grass and trees are planted, etc. This treatment method seriously pollutes the environment. For arid and rainless areas, reclaimed land is prone to water leakage. Water is very likely to spontaneously ignite and burn after contact with sulfur-containing gangue, producing a large amount of harmful gases such as SO2 and CO2. At the same time, this treatment method occupies a large amount of land and is prone to soil and groundwater pollution. Therefore, the harmless treatment of sulfur-containing gangue solid waste is an urgently needed technology.

[0003] At present, the harmless treatment of sulfur-containing coal gangue in the industry mainly adopts physical sorting methods, and the sorting technology of pyrite is gravity method, one is trapezoidal jig technology, and the other is shaking table technology, both of which use coal gangue with a sulfur content of more than 10% as raw materials. However, the sulfur content in most sulfur-containing coal gangue is 3%~10%. If this kind of sulfur-containing coal gangue is directly used as raw material to produce pyrite, the power consumption is large, the production cost is high, and the pyrite product produced has a high carbon content. Carbon is the main harmful impurity in the production of sulfuric acid from pyrite, and the generated carbon monoxide poisons the SO2 to SO3 catalyst. Therefore, the high carbon content will directly affect the sales of the product. Summary of the invention

[0004] The invention overcomes the shortcomings of the prior art and provides a method for harmless treatment of sulfur-containing coal gangue and resource utilization.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A method for harmless treatment and resource utilization of sulfur-containing coal gangue, characterized in that it comprises the following steps:

[0007] Step 1, screening and crushing the sulfur-containing coal gangue to obtain coal gangue particles;

[0008] Step 2, sorting the gangue particles with a jig and enriching the pyrite;

[0009] Step 3, dehydrating the bottom flow of the jig through a bucket elevator to obtain pyrite-enriched gangue; dehydrating the overflow of the jig through a dehydration screen to obtain coal product 1; concentrating the water under the dehydration screen through a concentrating cyclone, dehydrating the bottom flow of the concentrating cyclone through a striking arc screen and further dehydrating it through a coal slime centrifuge and then mixing it with coal product 1;

[0010] Step 4, the overflow water of the concentrating cyclone in step 3, the water under the striking arc screen, and the centrifuge liquid of the coal slime centrifuge are clarified and recycled;

[0011] Step 5, crushing the pyrite-enriched gangue to obtain high-sulfur gangue fine particles;

[0012] Step 6, sorting the high-sulfur gangue fine particles enriched in the pyrite in step 5 by a ladder jig;

[0013] Step 7, dewatering the bottom flow of the trapezoidal jig through a dewatering screen to obtain a pyrite product; introducing the water under the dewatering screen into a fishing pit, and dewatering the sediment in the fishing pit with a bucket elevator to obtain a fine-grained pyrite product; dewatering the overflow of the trapezoidal jig through a dewatering screen to obtain coal product 2, concentrating and clarifying the water under the dewatering screen through a deep cone concentrator, and solidifying the bottom flow of the deep cone concentrator through a diaphragm filter press to obtain coal slime 2;

[0014] Step 8: The overflow water in the scoop pit and the overflow water of the deep cone concentrator in step 7 are clean water and are recycled.

[0015] Furthermore, the size of the coal gangue particles obtained in step 1 is 15 to 25 mm, and the size of the coal gangue fine particles obtained in step 5 is 5 to 10 mm.

[0016] Furthermore, the method further comprises the following steps: crushing the pyrite product obtained in step seven into sulphur sand with a particle size of less than 2 mm by a fine crusher, and mixing the sulphur sand with the fine-grained pyrite ore as raw materials for preparing iron powder and sulphur.

[0017] Furthermore, the jig in step 2 is a one-stage structure, and the jig includes at least 8 air valves.

[0018] Furthermore, the overflow water of the concentrating cyclone in step 4, the water under the impact arc screen, and the centrifuge liquid of the coal slime centrifuge are concentrated and clarified by a deep cone concentrator.

[0019] Furthermore, the overflow water of the deep cone concentrator is recycled, the bottom flow of the deep cone concentrator is filtered through pressure filtration to obtain solidified coal slime, and the filtrate after pressure filtration is returned to the concentrator for treatment.

[0020] Furthermore, the coal slurry water feed concentration of the deep cone concentrator is 10-35 g / L, the underflow solid concentration of the concentrator is 350-450 g / L; and the overflow water solid content is 0.1-1.0 g / L.

[0021] Furthermore, the method further comprises the following steps: mixing the coal slime products separately, and selling the coal product one and the coal product two separately.

[0022] Compared with the prior art, the present invention has the following beneficial effects.

[0023] 1. The method provided by the present invention enriches sulfur-containing coal gangue with a sulfur content of 3% to 10%, and obtains pyrite-enriched gangue with a sulfur content greater than 10%, and then sorts the enriched gangue to obtain pyrite with a high sulfur content. The coal slime and low-calorie coal produced during the process can be supplied to the market as coal blending raw materials. The method thoroughly treats solid waste, does not discharge solid waste, and the water used in the treatment process is recycled, with less water consumption, which greatly reduces resource and energy consumption.

[0024] 2. High-efficiency deep cone concentrators have small footprints, good concentration and clarification effects, low investment and small installation. The high-efficiency concentrator can achieve a closed-loop cycle for washing water, which can be closed together with the factory building, and has low heating energy consumption. The single-stage multi-air valve intelligent jig is used instead of the multi-stage jig to enrich the pyrite. The single-stage multi-air valve intelligent jig improves the mineral stratification effect and the mineral sorting accuracy by increasing the number of air valves and changing the shape of the bellows, so that the enrichment and processing capacity of sulfur-containing coal gangue is larger. The single-stage type occupies a smaller area than the multi-stage type, which increases the processing capacity per unit time on the basis of reducing investment.

[0025] 3. The resources in the sulfur-containing coal gangue are fully utilized, and the products obtained can be used in the market. The sulfur-containing coal gangue is treated more thoroughly, without any solid waste discharge. The problem of high-sulfur coal gangue solid waste treatment is solved with lower energy consumption and cost. The requirements for raw materials are not high, and high-quality pyrite products can be produced for the production of iron powder and sulfur. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described below in conjunction with the accompanying drawings.

[0027] Figure 1 It is a schematic diagram of the process flow of the sulfur-containing coal gangue enrichment method of the present invention.

[0028] Figure 2 It is a schematic diagram of the pyrite separation process of the present invention. DETAILED DESCRIPTION

[0029] The present invention is further described below in conjunction with specific embodiments.

[0030] Generally, the sulfur content in sulfur-containing coal gangue is 3%~10%, which cannot be directly used as raw material for pyrite sorting. The reason is that there is coal in sulfur-containing coal gangue, and direct sorting of coal is easy to mismatch with pyrite. Carbon is the main harmful impurity in pyrite. When the content is high, the carbon monoxide generated poisons the catalyst for converting SO2 into SO3. Therefore, high carbon content will directly affect product quality and sales.

[0031] A method for harmless treatment and resource utilization of sulfur-containing coal gangue includes the following steps: first, pyrite in the sulfur-containing coal gangue is enriched. The enrichment method adopts a multi-air valve intelligent jig machine-high-efficiency deep cone concentrator combined process, which can effectively remove coal from the sulfur-containing coal gangue while enriching the pyrite to reduce the carbon content in the pyrite.

[0032] The composition of sulfur-containing coal gangue from a certain mine is shown in Table 1.

[0033]

[0034] In this embodiment, the dry total sulfur (St,d) content is 6.45%, which is lower than 10%, and cannot be directly used as a raw material for pyrite sorting. For the sulfur-containing coal gangue in this embodiment, the pyrite is first enriched in the sulfur enrichment workshop. The process of pyrite enrichment is as follows: First, the sulfur-containing coal gangue raw material is sieved with a 20mm sieve, and the sulfur-containing coal gangue with a particle size greater than 20mm is crushed to less than 20mm by a crusher, and mixed with the undersize to obtain coal gangue particles with a particle size of less than 20mm. The coal gangue particles with a particle size of less than 20mm are sent to a multi-air valve intelligent jig for sorting. The overflow of the jig is dehydrated by a dewatering screen to form coal product 1. The water under the dewatering screen is concentrated by a concentrating cyclone. The bottom flow of the concentrating cyclone is dehydrated by a striking arc screen to recover coarse coal slime. The coarse coal slime is further dehydrated by a coal slime centrifuge and mixed with coal product 1. The mixed product is medium-sulfur low-calorie coal and can be sold separately as a coal product. The bottom flow of the jig is the gangue after pyrite enrichment, which is used as the raw material for pyrite sorting after being dehydrated by a bucket elevator. The overflow of the concentrating cyclone, the water under the impact arc screen and the centrifuge of the coal slime centrifuge are concentrated and clarified by a deep cone concentrator. The overflow water of the deep cone concentrator is recycled; the bottom flow of the deep cone concentrator solidifies the coal slime through a diaphragm filter press, and the filtrate after filtration is returned to the deep cone concentrator for treatment. In this embodiment, the processing capacity of sulfur-containing coal gangue is 3 million tons / year. The sulfur enrichment workshop uses one φ350*6 concentrating cyclone group and four φ5000 deep cone concentrators, which can effectively guarantee the processing capacity and processing quality.

[0035] The sorting effect of the jig machine mainly depends on the stratification of the minerals. The better the stratification of the minerals, the higher the sorting accuracy. The traditional jig machine air valve is a 4-air valve. In this embodiment, firstly, the 4-air valve of the air chamber under the screen is changed to a multi-air valve, which improves the uniformity of the minerals being thrown up on the jig machine bed surface during air pressure, which is conducive to improving the stratification of the minerals on the bed surface; secondly, the bellows of the jig machine is changed to an air duct, the volume of the air chamber is greatly reduced, and the waveform of the compressed air is changed. When the air is compressed, the bed starts quickly and stops quickly, which reduces the delay phenomenon of compressed air and stopped air, which is conducive to the stratification of minerals; thirdly, the automatic control level of the main parameters of the jig machine such as air, water, feeding, discharge cycle, bed sensor, etc. is further improved, which is conducive to improving the sorting accuracy.

[0036] The feed concentration of coal slurry in the deep cone thickener is 10~35g / L, the bottom flow solid concentration of the deep cone thickener is 350~450g / L, the overflow water is clean water, the solid content is 0.1~1g / L, and the overflow water is recycled. The deep cone thickener has the characteristics of small footprint, small installation, and low investment. It can be enclosed with the factory building to reduce heating energy consumption.

[0037] After carbon removal, the pyrite enrichment gangue is used as the raw material for pyrite separation. The products after pyrite enrichment are shown in Table 2.

[0038]

[0039] Second, the sorting of pyrite requires fine particle size. Sorting after pyrite enrichment can effectively reduce the equipment investment of the sorting plant, alleviate the pressure on the water treatment system, and reduce power consumption and production costs.

[0040] After enrichment, the sulfur content of the pyrite enriched gangue reaches 11.62%, and it enters the pyrite sorting workshop. In the sorting workshop, the pyrite sorting process is as follows: the pyrite enriched gangue is crushed to particles below 8mm and sent to the trapezoidal jig for sorting. The overflow of the trapezoidal jig is dehydrated by the dewatering screen to obtain coal product 2; the water under the dewatering screen enters the thickening cyclone for concentration, and the bottom flow of the thickening cyclone is recovered by the striking arc screen to recover the coarse coal slime. The coarse coal slime is further dehydrated by the coal slime centrifuge and mixed with coal product 2. The overflow of the thickening cyclone, the water under the striking arc screen, and the centrifugal liquid of the coal slime centrifuge are concentrated and clarified in the deep cone concentrator, and the overflow water is recycled. The bottom flow of the concentrator is filtered through a diaphragm to solidify the coal slime to obtain coal slime product 2. The filtrate is returned to the deep cone concentrator for treatment. The bottom flow of the trapezoidal jig is dehydrated by the dewatering screen to obtain the pyrite product. The water under the dewatering screen enters the bailing pit, and the overflow water of the bailing pit is recycled. The sediment in the bailing pit is dehydrated by a bucket elevator to obtain fine-grained pyrite. The pyrite is crushed to less than 2mm by a fine crusher to obtain sulfur sand, which is mixed with fine-grained pyrite to be used as a raw material for preparing iron powder and sulfur, and can also be sold separately as a pyrite product.

[0041] In this embodiment, the pyrite sorting workshop uses one φ350*4 concentrating cyclone group and four φ4500 deep cone concentrators.

[0042] The product indicators of pyrite after pyrite sorting are shown in Table 3.

[0043]

[0044] Pyrite products are graded by sulfur content, with sulfur content greater than 48% being grade one, 45% to 48% being grade two, and 40% to 45% being grade three. It can be seen that the sulfur content of the final pyrite product reaches 45.6%, which can be used as a raw material for making iron powder and sulfur, and can also be sold directly as a product. In general, the pyrite produced reaches grade three and grade two, and in special cases, it can reach grade one.

[0045] Pyrite products can be directly used in the preparation of iron powder and sulfur.

[0046] The iron-sulfur separation method uses the patented technology of ZL 201210516527.0 to prepare iron powder and sulfur. Through experiments, it is found that the product quality is relatively good after the iron powder and sulfur are separated. The test indicators of iron powder and sulfur are shown in Table 4 and Table 5 respectively.

[0047] Table 4 Iron powder test results.

[0048]

[0049] Table 5 Sulfur test results.

[0050]

[0051] As can be seen from the table, the iron content of the produced iron powder is 66.75%, which is of high grade and has few harmful components. The sulfur grade is also very high, reaching 99.97%. At the same time, a large amount of heat is generated during the separation of sulfur and iron. The process system uses waste heat to generate electricity to achieve the utilization of all resources. The production of 240,000 tons / year of iron powder requires 12MW of waste heat power generation, which produces about 100 million kWh of electricity per year.

[0052] The methods for harmless treatment and resource utilization of sulfur-containing gangue proposed in this embodiment can be used for production applications. The moisture content of the pyrite product is 3% to 5%. After being placed for a period of time, the moisture content is below 1%. It can be directly used to produce iron powder and sulfur, and can also be sold separately as a raw material for making sulfuric acid. In this embodiment, the proposed method is relatively thorough in the treatment of sulfur-containing gangue, without the discharge of solid waste. It solves the problem of high-sulfur gangue solid waste treatment with lower energy consumption and cost, has low requirements for raw materials, and can produce high-quality pyrite products. A single-stage multi-air valve intelligent jig is used instead of a multi-stage jig to enrich pyrite. The single-stage multi-air valve intelligent jig improves the sorting accuracy of minerals and reduces the floor space by increasing the number of air valves and changing the shape of the bellows. The enrichment process of sulfur-containing coal gangue has a larger processing capacity, and the processing capacity per unit time and unit area has been increased. According to calculations, a 3 million tons / year (equivalent to 600t / h) pyrite enrichment plant has an installed capacity of 854kW and a full load of 597.8kW. The power consumption for processing sulfur-containing coal gangue is only 0.947kW·h / t. The power consumption of a general jigging coal preparation plant reaches 3-4kW·h / t, which greatly reduces energy consumption.

[0053] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Those familiar with the technology may modify or improve the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A method for harmless treatment and resource utilization of sulfur-containing coal gangue, characterized in that: The steps include: Step 1, screening and crushing the sulfur-containing coal gangue to obtain coal gangue particles; Step 2, sorting the sulfur-containing coal gangue particles with a jig and enriching the pyrite; Step 3, dewatering the jig underflow through a bucket elevator to obtain pyrite-enriched gangue; The overflow of the jig is dehydrated through a dehydration screen to obtain a coal product 1; the water under the dehydration screen is concentrated by a concentrating cyclone, the bottom flow of the concentrating cyclone is dehydrated by a striking arc screen and further dehydrated by a coal slime centrifuge before being mixed with the coal product 1; Step 4, the overflow water of the concentrating cyclone in step 3, the water under the striking arc screen, and the centrifuge liquid of the coal slime centrifuge are concentrated and clarified and then recycled; Step 5, crushing the high-sulfur gangue enriched with pyrite in step 3 to obtain high-sulfur gangue fine particles; Step 6, sorting the high-sulfur gangue fine particles in step 5 using a trapezoidal jig; Step 7, dewatering the bottom flow of the trapezoidal jig through a dewatering screen to obtain a pyrite product; introducing the water under the dewatering screen into a fishing pit, and dewatering the sediment in the fishing pit with a dewatering bucket elevator to obtain a fine-grained pyrite product; dewatering the overflow of the trapezoidal jig through a coal dewatering screen to obtain coal product 2, the water under the coal dewatering screen is concentrated and clarified by a deep cone concentrator, the overflow water of the deep cone concentrator is recycled, the bottom flow of the deep cone concentrator is filtered to obtain solidified coal slime 2, and the filtrate after the filter pressing is returned to the concentrator for treatment; Step eight: the overflow water in the scoop pit and the overflow water from the concentrator in step seven are clean water and are recycled.

2. The method for harmless treatment and resource utilization of sulfur-containing coal gangue according to claim 1, characterized in that: The size of the coal gangue particles obtained in step 1 is 15 to 25 mm, and the size of the high-sulfur gangue fine particles obtained in step 5 is 5 to 10 mm.

3. The method for harmless treatment and resource utilization of sulfur-containing coal gangue according to claim 1, characterized in that: The method further comprises the following steps: crushing the pyrite product obtained in step seven to less than 2 mm by a fine crusher to obtain sulphur sand, and mixing the sulphur sand with the fine-grained pyrite product to prepare iron powder and sulphur.

4. The method for harmless treatment and resource utilization of sulfur-containing coal gangue according to claim 1, characterized in that: The jig in step 2 is a one-stage structure, and the jig includes at least 8 air valves.

5. The method for harmless treatment and resource utilization of sulfur-containing coal gangue according to claim 1, characterized in that: The overflow water of the concentrating cyclone in step 4, the water under the impact arc screen, and the centrifuge liquid of the coal slime centrifuge are concentrated and clarified by the deep cone concentrator.

6. The method for harmless treatment and resource utilization of sulfur-containing coal gangue according to claim 5, characterized in that: The overflow water of the deep cone concentrator is recycled, the bottom flow of the deep cone concentrator is filtered to obtain solidified coal slime, and the filtrate after the filtration is returned to the concentrator for processing.

7. A method for harmless treatment and resource utilization of sulfur-containing coal gangue according to claim 1 or 6, characterized in that: The feed coal slurry water concentration of the deep cone concentrator is 10-35 g / L, the underflow solid concentration of the concentrator is 350-450 g / L; the overflow water solid content is 0.1-1.0 g / L.

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