Dry discharge of tailings Tailings dry discharge is a process method that the waste residue (i.e. tailings) extracted from valuable substances in ores is prepared into materials with a moisture content (mass percentage) of 10% ± 2 through concentration and dehydration process and then transported to tailings pond and waste dump for stockpiling or recycling.
Program controlled automatic hydraulic chamber filter press Its main process mode is: concentration equipment+dehydration equipment+conveying equipment; The selection of process equipment and transmission mode are determined by the material property, specific gravity, particle size distribution, treatment capacity and other index parameters of tailings slurry as well as the site geographical environment conditions.
Its main significance lies in alleviating the pressure of tailings pond capacity, reducing the potential safety hazard of tailings pond, increasing the means of tailings reuse, and obtaining a green and environment-friendly mine system.
Main problems: The disadvantage of dry discharge process of tailings is that it is difficult to dewater fine grained materials in tailings, especially in iron ore and gold ore selected for dry stacking. The particle size distribution of gold ore tends to be smaller due to production needs, and most of iron ore is due to more soil composition in open-pit mining. As for the difficulty in dewatering fine grained materials, many tailings enter the cyclone, Then it is fed to the vibrating screen, and then to the thickener. The underflow of the thickener returns to the vibrating screen. Although the processing capacity and operating load of the thickener are reduced, the thickening process of the thickener is cumbersome, and the infinite circulation of fine materials is gradually increasing. Due to the characteristics of the thickener, this problem can be caused for fine materials (- 200/80% or more) The thickening effect itself is not good, so the sedimentation process is long, and the underflow concentration does not meet the index requirements. The results of the same thickener and sedimentation tank are the same as those of the thickener. In order to find out a right process, we must first go on the right path. The problem is so obvious that we cannot face it, and the results are conceivable. 1. The above process is only a practical problem in the correct process 2. There are many complicated and wrong path processes everywhere. 3 We are exploring not only the dry tailings discharge process, but also other related process links that need attention (stockpiling, reuse, environmental protection, etc.) 4. The treatment of fine grained materials, through process means, will gradually reduce rather than increase them, This requires the selection of process mode, understanding of process equipment and selection of process equipment.
Tailings, one of the products of separation operation in mineral processing, have the lowest content of useful ingredients. Under the current technical and economic conditions, the ores that are not suitable for further separation are also the final tailings [1] 。
The lowest content of ingredients does not mean the lowest value. Tailings are considered by experts to be an important treasure with great excavation potential and high secondary utilization. Leaving aside the benefit value it can bring, the massive accumulation of tailings requires a large tailings pond, which will cause great environmental pollution, and it is also easy to cause tailings dam break accidents, bringing potential safety hazards. Therefore, dry discharge of tailings is urgent!
Latest national policies
Ministry of Industry and Information Technology , Ministry of Science and Technology, Ministry of Land and Resources and State Administration of Work Safety And other relevant departments have recently prepared the Special Plan for Comprehensive Utilization of Metal Tailings (2010~2015), and required relevant regions and departments to strictly follow it [2] 。 Analysis of current situation of tailings in China
By 2007, the total amount of tailings accumulated in China had reached 8.046 billion tons, and in 2007 alone, 1 billion tons had been discharged. The massive stockpiling of tailings has brought many problems to national resources, environment, safety and land. However, the pressure is great, and the potential for development and utilization is also great.
The problem of comprehensive utilization of tailings in China lies in the low utilization rate of tailings and the lack of proper awareness of dry drainage treatment of tailings in many regions; The weak awareness of tailings pollution prevention and control has hindered the effective development of relevant pollution control work; The technical input of dry tailings disposal is insufficient.
Tailings dry discharge screen 2. After the tailings are concentrated and dewatered, dry discharge can not only save the construction cost and routine maintenance cost of the traditional tailings pond, but also make full use of the artesian backwater, and can also greatly save the floor area and eliminate the potential safety hazard of the tailings pond. In addition, in the process of mine production, it can also eliminate the potential safety hazards in the mined out area, save safety investment, rehabilitate the landform, save environmental governance funds, help geological environment protection, and achieve waste replacement.
3 The equipment, technology and process used in the dry tailings discharge process are innovative, which opens up a new way for the comprehensive treatment of tailings stacking and goaf.
4. Small investment and great benefit. After calculation, the process of filling the mined out area with dry tailings discharge will save investment in fixed assets, safety management funds, ecological environment management funds, energy conservation and emission reduction, and tailings pond maintenance costs.
1 Cyclone and Dewatering vibrating screen After the combined tailings are concentrated through the cyclone, the underflow enters High frequency vibrating dewatering screen Dewatering can make the water content of tailings within 16%, so as to achieve the purpose of dry discharge and stacking of tailings. This is the most economical and practical way in the market with good effect, less investment and high efficiency. 2. The direct use of concentrated mechanical filtration has a large initial investment and a small scope of application, and sometimes it cannot meet the production efficiency or dehydration degree.
Tailings dry discharge process
1、 Tailings dry drainage and comprehensive treatment
2、 New technology of red mud separation and washing
technological process 1. Alkali attached to discharged red mud can be reduced to: 6kg/t (dry red mud);
2. Cancellation of red mud separation tank and washing tank can save a lot of construction investment and simplify alumina Process, improve production environment, significantly reduce energy consumption, and improve alumina Yield. (1) Thickener+cyclone+ Belt filter (The belt filter can be regarded as a modification of the drum filter). The process equipment combination system can be used for continuous production and is suitable for medium and coarse tailings, but the power consumption for production and operation is high, the cost is high, and the investment is large. The moisture content of conventional products is 15%~18%. (2) Thickener+ ceramic filter (The ceramic filter can be regarded as a modification of the disc filter). The process equipment combination system can be used for continuous production and is suitable for dewatering of medium and fine grade tailings and concentrates, but it is difficult for dewatering of coarse grade and - 0.037 mm grade which account for 80% of pulp. Its advantage is low water content after dehydration, and the water content can be less than 10%. The disadvantage is that the equipment input is high, and the ceramic filter plate is easy to be blocked, especially for materials containing fine particles and quartz, the cleaning process is complex and strict. Due to the high equipment input, the process equipment combination system is generally used for concentrate dewatering. (3) Thickener+box filter press or Vertical filter press 。 The process equipment combination system is suitable for medium and fine grade materials, and can still be used when the pulp particle size - 0.037mm accounts for 95%, and the product moisture is 15%~25%. The vulnerable parts of the process equipment combination system are mainly filter cloth and pump flow passage parts, with a general service life of 1-3 months, and only 10-20 days in case of improper use. The ore discharge of the process equipment combination system is discontinuous, and buffer equipment may be required for some processes. The box filter press has developed to a large scale. The vertical filter press is expensive, but its production capacity is large and its moisture content is low. It is often used for concentrate dewatering. (4) Cyclone+thickener+dewatering screen. This combination is a new dehydration process and equipment developed (it can be called the third generation dehydration process equipment). This combination is almost applicable to the dehydration requirements of all minerals within - 325 mesh 80%. The scheme has low investment and cost, and the operation cost is ceramic filter Belt filter 1/2 of the box filter press, this machine has almost no vulnerable parts, and the service life of the dewatering screen is long. In addition, for extremely fine minerals, a combined process: thickener+dewatering screen+filter press can also be used to complete the dewatering project. 
