The filter press is an important equipment for the closed-loop circulation of coal slurry recovery and washing water in the coal preparation plant, which has promoted the continuous improvement and updating of the filter press and led to the emergence of new types of filter presses. With the rapid development of mechanized coal mining technology in China, the types of coal preparation plants are becoming larger and larger, leading to problems such as poor coal quality and increased coal slurry. Higher requirements have been put forward for the filter press equipment in coal slurry water treatment.
1、 The fast opening diaphragm filter press was developed in China as early as the late 1990s and was put on the market. It is a KM type diaphragm filter press, which is a pressurized filter press equipment that uses filter media to separate discrete insoluble solid particles from liquids. Compared with traditional box filter presses, its advantages are as follows:
（1） Adopting multi port feeding, fast feeding speed, uniform fabric, and good cake making effect;
（2） Adopting synchronous compression and control technology of master and slave cylinders, the filter plate is uniformly and reasonably stressed, with good edge sealing, and no spraying is required when under high pressure, high flow rate, or slurry feeding;
（3） By using hydraulic drive, grouping opening and closing, circular ring chain to open the filter plate group, and filter cloth displacement unloading mechanism, unloading has been achieved; Adopting the secondary diaphragm pressing and dehydration process, the moisture content of the filter cake is low;
（4） A filtrate flow detection device has been developed, and the filter chamber is well filled, achieving automation of the entire operation process of the pressure filtration system.
2、 The basic filtering mechanism of the quick opening drying filter press consists of spaced hot press diaphragm filter plates and drying plates, which complete the mechanical filtration of suspension and cake in the filter chamber; Immediately entering the hot press filtration drying and dehydration stage, a fluid heat medium (steam or heat transfer oil) is introduced into the drying plate while vacuuming the drainage channel, and the filter cake is mechanically squeezed by a diaphragm. In a short period of time, the capillary water of the filter cake near the drying plate evaporates due to heat conduction, and the generated steam rapidly expands, driving the capillary water of the filter cake far away from the drying plate to emerge from the surface of the filter cake in liquid form and be removed.
According to the relationship between moisture content and calorific value in coal, for every 1% decrease in moisture content, the calorific value can increase by 4118kJ, and the storage of coal slurry with reduced moisture content will not cause blockages. The quick opening drying filter press integrates mechanical filtration and thermal drying into one operation, not only achieving deep dehydration of flotation clean coal, but also increasing the value of coal slurry products from coal preparation by-products to commercial thermal coal. Due to the fact that the price of thermal coal is 3-4 times that of coal slurry, using this equipment can bring significant economic benefits to enterprises. In recent years, the coal slurry production in coal preparation plants has been increasing, and the fast opening drying filter press has perfectly catered to this market gap, with broad development prospects, and is a development direction for fast opening filter presses for coal in the future.
3、 At present, the pressure filtration technology is still constantly developing and exploring. For example, drying technology can be integrated into pressure filtration technology to lower the moisture content of the feed. In addition, under constant volume heating, the pressure inside the container will naturally increase, which will reduce the required air volume and pressure for the existing pressure filter; From another perspective, the integration of pressure filtration technology into drying technology will not increase energy consumption. With the further development of pressure filtration technology, this idea may become a reality in the near future.