In coal, mineral processing and other industries, the teetered bed separator has become an important sorting equipment by virtue of its high efficiency and economic characteristics. Sorting accuracy as a key indicator of its performance, directly affecting product quality and economic benefits. However, the sorting accuracy of the teetered bed separator is affected by a variety of factors, and it is important to understand these factors and master the methods to improve the sorting accuracy to optimise the sorting process and improve the resource utilisation rate.
一.Factors affecting the sorting accuracy of the teetered bed separator
1.Equipment structure factors
Shape and size of the sorting tank: the shape and size of the sorting tank determines the distribution of the water flow and the movement of particles in the interference bed. Generally speaking, the proportion of the diameter and height of the sorting tank should be reasonable, if the diameter is too large, the rising speed of the water flow is difficult to be uniformly distributed, which will easily lead to turbulence in the sorting area, so that the particles can not be separated in accordance with the predetermined settlement law; if the height is too high, the particles in the bed of too long a time to stay, which will increase the opportunity for the mixing of fine particles and reduce the accuracy of the sorting. In addition, the irrational design of the bottom of the sorting tank may lead to local concentration or dispersion of water flow, destroying the stability of the interference bed. Water distribution device: water distribution device is a key component to ensure the uniform rise of water flow in the interference bed. If the opening rate and aperture distribution of the water distribution device are not uniform, it will make the water flow into the sorting tank when there is a difference in the flow rate, resulting in water flow turbulence in the bed. Overflow weir and bottom flow opening: the height and shape of the overflow weir affects the discharge of fine coal and the sorting effect. If the overflow weir is too high, the liquid level in the disturbing bed will rise, increasing the residence time of the particles in the bed, which may lead to fine particles being mixed into the fine coal; if the overflow weir is too low, the fine coal may be discharged too fast, and some particles that have not been sufficiently sorted will also be taken out, which will reduce the quality of the fine coal. Meanwhile, the size and adjustment of the bottom flow opening also affect the tailings discharge and bed stability.
2.Operating parameter factors
Rising water velocity: Rising water velocity is one of the core parameters affecting the sorting accuracy of the interfering bed sorting machine. Appropriate rising water velocity can make the particles in the bed form a stable state of interference settlement, to achieve accurate sorting by density. When the rising water velocity is too high, the particles will be carried upward by the water current, resulting in heavy particles can not be effectively settled, mixed into the light products; while the rising water velocity is too low, the light particles can not be adequately suspended, and will be settled into the tailings with the heavy particles, which reduces the yield of refined coal and sorting accuracy. Feeding flow rate: the size of the feeding flow rate directly affects the concentration and movement state of the particles in the interference bed. Feeding flow is too large, it will make the concentration of particles in the bed too high, and the mutual interference between particles will be intensified, which will affect the settling speed of particles and sorting effect; Feeding flow is too small, it will make the bed unstable, and the particles can not be fully dispersed in the bed, and it will also reduce the sorting precision.
3.Characteristic factors of the feed
Particle size composition: the particle size composition of the feed has a significant impact on the sorting accuracy of the interfering bed sorting machine. Generally speaking, the interfering bed sorting machine is suitable for sorting materials with a certain range of particle size. When the content of fine particles in the feed is too high, the fine particles will form colloidal substances in the bed, increase the viscosity of water, impede the settlement of coarse particles, resulting in poor sorting effect between coarse particles and fine particles; at the same time, the fine particles are easy to be adsorbed on the surface of the coarse particles, so that the apparent density of coarse particles changes, affecting the accuracy of sorting by density. When the content of coarse particles in the feed is too high, the coarse particles will settle quickly, destroying the stability of the bed and also reducing the sorting accuracy. Density composition: the density composition of the feed directly determines the difficulty of sorting. If the density difference between light and heavy particles in the feed is large, the sorting is relatively easy, and the sorting accuracy is also high; but when there are a large number of intermediate density particles in the feed, these particles in the disturbed bed of the settlement behaviour is complex, and it is easy to mis-select them, resulting in a decline in the sorting accuracy. In addition, the fluctuation of density composition in the feed will also bring difficulties to sorting, and it is necessary to adjust the operating parameters in time to ensure the sorting precision.
二.Methods to enhance the sorting accuracy of the interference1. Bed sorter
1.Optimise the equipment structure
Reasonable design of the sorting tank: according to the nature of the material to be processed and the processing capacity, the ratio of the diameter and height of the sorting tank can be reasonably determined. Generally speaking, for the common teetered bed separator, the ratio of diameter and height can be controlled within a certain range to ensure the uniform distribution of water flow in the bed and the effective sorting of particles. At the same time, the shape of the bottom of the sorting tank is optimised, and a reasonable inflow structure is adopted so that the water flow can rise uniformly and reduce the generation of turbulence. In addition, set appropriate anti-stick and wear-resistant materials on the inner wall of the sorting tank to prevent material adhesion and abrasion and ensure the normal operation and sorting effect of the sorting tank. Improvement of water distribution device: choose suitable water distribution device to ensure uniform distribution of the opening rate and hole diameter of the water distribution holes, and improve the uniformity of the water flow. New water distribution technology can be used, such as porous plate water distribution, ring water distribution, etc., so that the water flow can be evenly dispersed when entering the sorting tank. Regularly check and clean the water distribution device to prevent the water distribution holes from being blocked and worn out to ensure the effect of water distribution. At the same time, improve the installation precision of the water distribution device to ensure that its level meets the requirements and avoid water flow offset. Optimise the overflow weir and underflow opening: reasonably adjust the height and shape of the overflow weir according to the requirements of the sorting process. Through test and practice, determine the best overflow weir height to ensure the quality and yield of fine coal. For the underflow opening, an adjustable structure is adopted, and the size of the underflow opening is adjusted in time according to the nature of the incoming material and the operation situation, so as to ensure the smooth discharge of the tailings and the stability of the bed. At the same time, the maintenance of overflow weir and underflow opening is strengthened to prevent wear and clogging and ensure their normal operation.
2.Optimise the operating parameters
Precise control of the rising water flow rate: a high-precision water flow rate monitoring device is installed to monitor the rising water flow rate in real time. According to the nature of the feed material and sorting requirements, adjust the flow rate or pressure of the water pump to precisely control the rising water velocity within a suitable range. Establish the mathematical model of rising water velocity and sorting effect, use advanced control algorithms to achieve automatic adjustment of rising water velocity to adapt to changes in the nature of the feed to ensure the stability of sorting accuracy. Stabilise the feeding flow: adopt constant flow feeding equipment, such as quantitative pumps, variable frequency speed feeders, etc., to ensure the stability of the feeding flow. Set the monitoring and feedback system of feeding flow, when the feeding flow fluctuates, adjust the operating parameters of the feeding equipment in time, so that the feeding flow is restored to the set value. At the same time, reasonably arrange the production process to avoid the fluctuation of feed flow caused by the fluctuation of other links, to ensure the stable operation of the interfering bed sorting machine.
3. Improve the characteristics of the incoming material
Pre-grading treatment: Before the incoming material enters the disturbed bed sorting machine, adopt suitable grading equipment, such as vibrating screen, hydrocyclone, etc., to pre-grade the incoming material. Separate the materials with large differences in particle size, so that the composition of the particle size of the materials entering the interfering bed sorting machine is more uniform, and reduce the influence of fine particles and coarse particles on the sorting effect. For materials with too high content of fine particles, some of the fine particles can be pre-separated through classification, and other suitable sorting methods can be used to improve the overall sorting accuracy. Desliming treatment: for the feed material with high coal sludge content, desliming treatment is carried out. Desliming screen, arc screen and other equipment can be used to separate the coal sludge from the feed. The desliming treatment can reduce the water flow resistance in the disturbed bed, improve the settling characteristics of the particles, and reduce the influence of coal sludge on the sorting effect. In addition, methods such as adding flocculants can be used to promote the agglomeration and settlement of coal sludge and improve the desliming effect. Uniform nature of the feed material: strengthen the management and deployment of the feed material, try to ensure that the density composition and particle size composition of the feed material is relatively uniform. Establish raw material storage and blending system, make reasonable matching and mixing for different sources and different nature of raw materials to reduce the fluctuation of the nature of the feed material. At the same time, strengthen the real-time monitoring of the nature of the feed material, when the nature of the feed material is found to have large changes, timely adjustment of the operating parameters of the sorting equipment to ensure that the sorting accuracy is not affected.
In summary, the sorting accuracy of the teetered bed separator is affected by a variety of factors such as equipment structure, operating parameters and feeding characteristics. In the actual production process, according to the specific circumstances, we need to comprehensively use various methods to effectively improve the sorting accuracy of the teetered bed separator.
