Coal mine water treatment sludge filter press

                          Coal mine water treatment sludge filter press

1 Characteristics of coal mine drainage water quality and sludge treatment plan

Coal mine water treatment sludge filter press. Coal mine drainage is divided into mine drainage, open-pit drainage and drainage drainage. The water quality of coal mine drainage should be designed according to the measured water quality data or the measured water quality data of similar projects in similar mining areas.

1) Water quality characteristics of underground drainage. Downhole drainage is composed of downhole water gushing and underground production drainage. It is mainly polluted by underground coal mining activities. The water quality is black and the suspended solids exceed the standard (suspended solids are mainly coal ash). The main conventional pollution indicators include SS and oil. SS is 300 ~ 3 000 mg/L; oil is 1.0 ~ 20.0 mg/L.

2) Water quality characteristics of internal drainage. The drainage in the open pit is the waste water collected in the open pit, including groundwater seepage and atmospheric precipitation, mainly suspended matter, and the water quality is similar to that of underground drainage. The main conventional pollution indicators include SS and oil. SS is 600 ~ 3 000 mg/L; oil is 1.0 ~ 20.0 mg/L.

3) Water quality characteristics of drainage and drainage. The drainage water quality of open-pit mines is greatly affected by the local hydrogeological conditions, and should be designed according to the measured data. If there is no measured data, it can be determined by referring to the borehole water quality data in the coalfield geological survey report.

4) Coal mine sludge characteristics and conventional treatment methods. Sewage treatment plant sludge is roughly divided into three types: biochemical sludge, physical and chemical sludge, and physical and chemical biochemical mixed sludge. Coal mine drainage has relatively high suspended solids, mainly coal ash discharged to the ground with water, which belongs to inorganic physicochemical sludge. The density of lignite is generally 1.05-1.2 t/m3, that of bituminous coal is 1.2-1.4 t/m3, and that of anthracite is 1.35-1.8 t/m3. The sludge composed of coal and gangue has good settling properties, and after coagulation and precipitation , After filtration, the general removal rate of suspended solids is 80% ~ 90%. Moreover, coal slime often contains a certain amount of oiliness, and the better the coal quality, the greater the oiliness. In addition, during the collection of underground drainage and the storage of underground water tanks, massive or large particles have settled and rarely can be discharged to the ground. A small amount brought to the ground adjustment tank will continue to settle in the adjustment tank and enter the sludge dewatering tank. There are few large particles in the link, and the moisture content of the coal slime is generally around 95% to 98%. The sludge is large in size and difficult to deal with. In summary, the sludge produced by the mine water treatment system has the following four characteristics: inorganic sludge, good settling properties, oily, and small particles. Sludge treatment is usually divided into two types: sludge dehydrator process and sludge drying process. The conventional process is: ① sludge→concentration→digestion→natural drying→final disposal; ②sludge→wet sludge pool→ Natural drying→transportation; ③sludge→concentration→mechanical dehydration→final disposal.

2 Overview of Coal Mine Sludge Treatment

In recent years, with the enhancement of environmental protection awareness, new coal mine sludge treatment has gradually adopted mechanical dehydration. Mechanical dehydration not only reduces land occupation, but also has high dehydration efficiency, which brings great convenience to the final disposal of sludge and reduces environmental impact. Pollution, but the initial investment and daily operating costs are high. Sludge mechanical dehydration methods include vacuum suction filtration, pressure filtration and centrifugation. Generally, the moisture content of vacuum filtration dewatered cake is about 70%, that of press dewatering is 45%~80%, and that of centrifugal dehydration is about 80%. At present, there are mainly three types of sludge dewatering equipment: centrifuge, belt filter press, and plate-and-frame filter press. Vacuum filters are gradually being used due to the disadvantages of high water content in sludge, high noise, many auxiliary equipment, complicated procedures, and high operating costs. Eliminated; although the plate and frame filter press has high equipment and civil construction costs, it is simple to operate and has a high sludge dewatering rate.

3 Analysis of coal mine sludge dewatering equipment

3.1 Belt filter press dewatering machine The belt dewatering machine relies on the tension of the filter belt itself to squeeze the sludge layer and squeeze out the capillary water in the sludge layer, thereby obtaining a mud cake with a high solid content and realizing sewage The mud is dehydrated. The belt filter press dehydrator consists of a filter belt, a roller cylinder, a filter belt tensioning system, a filter belt deviation adjustment system, a filter belt flushing system and a filter belt driving system, and is equipped with a hydraulic adjustment device and a cleaning device. The belt dewatering machine is less affected by the fluctuation of sludge load, has low moisture content in the sludge, works stably and consumes less energy, and does not require high levels of operating personnel. Since the belt filter press dehydrator entered the country earlier, the supporting equipment and services are relatively complete, the experience in use is relatively rich, and it has universal applicability, which is more recognized by the construction party.

3.2 Centrifugal dehydrator Centrifugal dehydrator is mainly composed of a reloader and a screw conveyor with a hollow shaft. After the sludge is sent into the drum by the hollow shaft, it is immediately thrown into the hub cavity under the centrifugal force generated by high-speed rotation. The sludge particles have a large specific gravity, so the centrifugal force generated is also large, and they are thrown and pasted on the inner wall of the rotor to form a solid layer; the water density is small, and the centrifugal force is also small, so a liquid layer is only formed inside the solid layer. The sludge in the solid layer is transported to the cone end of the conveyor under the slow push of the screw conveyor, and is continuously discharged through the outlet around the conveyor. The centrifugal dehydrator has the disadvantages of high noise and easy blockage of the sludge outlet. The advantage is that it operates continuously and has low requirements on the moisture content of the feed material. The slurry can not be concentrated, thereby saving the investment in the sludge concentration tank. However, the centrifuge dehydrator is greatly affected by the fluctuation of the sludge load, has high requirements on the quality of the operating personnel, and consumes a lot of power. Therefore, general sewage treatment plants, especially large-scale treatment plants, rarely use the centrifugal dehydration process. With the improvement of machinery manufacturing and control level, the dehydration technology of centrifugal dehydrator has made great progress at home and abroad, and similar domestic products are relatively mature, especially in small sludge dewatering projects, which can guarantee the treatment effect and have Price advantage, you can boldly choose this kind of domestic products.

3.3 Plate and frame filter press dehydrator The plate and frame filter press arranges the filter plates and filter frames alternately in parallel, and by pressing the filter plates and filter frames, a filter press chamber is formed between the filter plates and filter frames, and the filter cake Accumulated on the filter cloth in the frame, after loosening the filter plate and filter frame, the mud cake will peel off from the filter frame to complete the sludge dehydration. Plate and frame filter presses generally occupy a large area, operate intermittently, have high labor intensity, low efficiency, and poor operating environment. In recent years, in order to meet the requirements of sewage treatment, the operation processes such as filter press, filter plate movement and filter cloth oscillation have gradually realized the automatic operation of the system, which has greatly improved the working environment. Coal slime filter presses in coal preparation plants mostly use plate and frame filter presses. The slime water in coal preparation plants is almost the same as the sludge produced by mine water treatment systems in nature. Judging from on-site feedback, the results are good. Compared with other types of dewatering machines, the plate and frame filter press has the highest solid content in the mud cake and produces less dry mud. Ignoring the labor intensity and working environment, considering the stability and reliability of the system operation, the plate and frame filter press machine should be the first choice.

3.4 Screw press sludge dewatering machine The Screw press  sludge dewatering machine is a new type of equipment that has appeared in the domestic market in recent years. The principle of dehydration is: after the sludge is concentrated by gravity in the thickening part, it is transported to the dewatering part. In the process of advancing, as the filter seam and screw pitch gradually become smaller, and under the blocking effect of the back pressure plate, internal pressure is generated and the volume is continuously reduced. , to achieve the purpose of full dehydration. The price of the Screw press sludge dewatering machine is relatively expensive, and the processing capacity is small. The main advantages are not easy to block, save water and electricity, safe operation, small footprint, and durable. Since the screw press sludge dewatering machine entered the domestic market late, The market share is low, especially in the field of coal mine water treatment. Compared with the commonly used plate and frame filter press, belt filter press and centrifugal dehydrator, it needs to increase the actual engineering application to summarize its role in coal mines. performance characteristics.

4 Comparison and selection of dehydration equipment

4.1 Performance comparison of conventional dehydration equipment See Table 1 for the comparison of belt filter press, plate and frame filter press and centrifugal dehydration machine.

4.2 Selection and application of dehydration equipment According to the performance comparison of different types of dehydration machines, combined with coal mine sludge characteristics, operating conditions, personnel quality, requirements for mud cakes, and capital costs, a reasonable choice can be made.

The Chaoyang Open-pit Coal Mine of Luneng Baoqing Coal Electrochemical Development Co., Ltd., the Hesi Gewula Open-pit Coal Mine, the Dahai Ze Coal Mine of Shendong Tianlong Group Co., Ltd., and the Maweigou Coal Mine of Boda Jinglu Energy Co., Ltd. in Shouyang County, Shanxi Province designed by our institute The common feature of these mines is that in order to save engineering investment and reduce daily operating costs, the sludge dewatering equipment adopts a belt filter press dewatering machine. The feedback information from actual operation is that the sludge dehydration effect is better, but the filter belt needs to be replaced frequently. The water consumption is large, the environmental sanitation of the operation room is poor, and the management cost is high. The Fanjiacun Coal Mine of Mengtai Fanjiacun Coal Industry Co., Ltd. in Ordos City, the Southwest Cheng Mine of Changzi County, Shanxi Province, and the Muduchaideng Mine of Yihua Mining Resources Co., Ltd. of Ordos City use plate and frame dehydrators. During actual operation, The moisture content of the mud cake is low, the equipment is easy to block, it needs to be washed frequently, the equipment needs to be replaced, and manual operation is labor-intensive. Shenyang Coal Industry (Group) Co., Ltd. Hongyang No. 3 Mine Wastewater Treatment Project, Shenyang Coking Coal Co., Ltd. Xima Coal Mine, Shaanxi Yanchang Petroleum Group Hengshan Weiqiang Coal Industry Co., Ltd. Weiqiang Mine and Coal Preparation Plant, Datong Coal Mine Group Co., Ltd. Centrifugal dewatering machines are used for dewatering sludge in the Madaotou Mine of the company.The main consideration is to reduce the cost of civil engineering and save space. In the actual sludge dewatering process, due to the limited management and maintenance level of workers, the failure rate is slightly high, which affects the normal water treatment operation. At the same time, the moisture content of the coal slime is high, the solid content of the filtrate is high, and the noise is large. It is understood that there are more or less certain defects and deficiencies in coal mine water treatment sludge dehydration equipment, some are due to product quality problems, and some are management problems. Generally speaking, the management of coal mines is relatively extensive, and water treatment is not given enough attention in daily management, which often leads to poor system operation, and even leads to the entire water treatment system being idle after completion. In order to improve the effect of sewage sludge treatment, it is necessary to strengthen communication with the construction party during design, understand the construction party's experience, management methods and use requirements, and select a sludge dehydrator suitable for this project according to the water quality characteristics.

5 Conclusion According to the characteristics of coal mine water treatment itself, selecting the coal slime water treatment process and equipment suitable for this project is an important link that cannot be ignored in water treatment. For profit, improve the environment, and can bring certain economic and environmental benefits.

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