| The heavy medium separation process has the advantages of high efficiency,wide adaptability to coal types,and high separation accuracy.It is the leading and preferred process of coal preparation plants in China.Saving costs and reducing consumption is an inevitable choice and an important issue for coal companies to achieve sustainable development in the context of national supply-side reform and coal capacity supply and demand policy reform.Therefore,further reducing the medium consumption in the heavy medium separation process has become a hot spot in the current coal preparation plant to improve the process and increase economic benefits.Media consumption is the main production cost of a coal preparation plant.A large amount of research literature and production site practice show that magnetic separation tailings account for more than 60% of the media loss.At present,there is still in lack of equipment and processes for the targeted recovery of magnetic separation tailings.Based on this article,we systematically studied the medium migration law in the actual production process of the coal preparation plant,systematically studied the properties and magnetic composition of the magnetic separation tailings,designed and developed a new type of disc magnetic separator and conducted semi-industrial tests to reduce the medium Consumption provides a new technical approach.The main conclusions are as follows:Clarified the law of medium migration in the production process of coal preparation plant.The research results of the medium migration characteristics in the production process of the coal preparation plant show that: 56.39% of the medium enters the underflow and 43.61% enters the overflow during the separation process of the heavy medium cyclone;0.03% of the medium enters the gangue and 0.04% enters during the dehydration and medium recovery process Clean coal,0.19% into the magnetic separation tailings.There are two media loss paths,namely: product take away,accounting for 0.07% of the incoming media,accounting for 26.92% of the total media loss;magnetic separation tailings taking away,accounting for 0.19% of the incoming media,accounting for 73.08% of the total media loss.The mineral phase composition and magnetic composition of the magnetic separation tail are clarified.The main components of magnetic separation tailings are Si and Al,and the content of Fe is 3.33%.The occurrence form of iron element is mainly magnetic iron,with a content of 2.17%,accounting for 65.17%;followed by hematite,with a content of 0.56%,accounting for 16.82%.In the magnetic separation tailings,the dominant particle size of magnetic materials is-0.045 mm,and the yield is 88.82%.As the background field strength decreases,the magnetic substance content in the magnetic separation tailings first stabilizes above 90%.When the field strength is less than 0.03 T,the magnetic substance content drops rapidly to 84.74%.To ensure that the magnetic substance of the magnetic separation tailings is fully recovered,The background field strength should be greater than 0.03 T.On the basis of clarifying the characteristics of the magnetic separation tailings,the magnetic system structure of the permanent disk type strong magnetic separator is designed.The effects of the arrangement of the magnetic system,the material of the magnetic block,the arrangement of the relative magnetic system of the magnetic disk,the spacing of the magnetic disk,and the width of the magnetic block on the magnetic field distribution are studied.Reduce the chance of the magnetic objects adsorbed on the disk to flip,reduce the magnetic objects lost due to the flip,and ensure a higher recovery rate of the magnetic objects;the permanent magnet block adopts Nd Fe B permanent magnetic material to ensure a higher magnetic field strength.The surface magnetic field strength can reach 0.58 T,and the center of the adjacent disk can reach 0.2T;the arrangement of the opposite poles of the opposite magnetic poles of the adjacent disks can reduce the area of the zero magnetic field area in the magnetic field compared with the arrangement of the same poles of the relative magnetic poles;The processing capacity of the equipment is reduced,the strength of the magnetic field is increased,but the zero magnetic field area in the magnetic field cannot be eliminated.To ensure the processing capacity of the equipment,the distance between the magnetic disks is 90mm;The magnetic block width is 20 mm to eliminate the zero magnetic field in the magnetic field.At this time,the magnetic field strength of the disk surface can reach 0.36 T,the center of the adjacent disk can reach 0.25 T,and the magnetic field strength of the magnetic field area is all greater than 0.03 T.Designed and processed the permanent magnetic disk strong magnetic separator,and carried out semi-industrial experiments.The results show that: with the increase of the disk speed,the recovery rate of the magnetic substance increases first and then decreases;with the increase of the processing capacity,the recovery rate of the magnetic substance is basically unchanged,and the recovery rate of the magnetic substance shows a downward trend after 400m3/h;With the increase of the height of the weir,the recovery rate of the magnetic substance shows an upward trend.After 25 cm,the recovery rate of the magnetic substance is basically unchanged,and remains above 88%.Finally,when the disk speed is 6r/min,the height of the overflow weir in the tank is 25 cm,and the processing capacity is 400m3/h,the recovery rate of magnetic substance is 88.83%.It provides a new technical way for the coal preparation plant to reduce medium consumption.The total iron content of the disc magnetic separator tailings is 0.45%,which is 3% lower than the magnetic separation tailings of the coal preparation plant,and the magnetic iron content is 0.26%,which is 2% lower than the magnetic separation tailings of the coal preparation plant.This thesis has 59 figures,19 tables and 62 references. |
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