新疆邢美煤矿生产硅煤的选煤工艺设计实践

The coal preparation process for production silicon coal at Xingmei Coal Mine from Xinjiang Uygur Autonomous Reign:process design and practice

工业硅用煤简称硅煤,其产品指标要求高,相应售价也高。通过对邢美煤矿相关煤样的煤质分析,明确了该矿生产硅煤的可行性及合理的产品结构和生产工艺,并最终完成了该矿生产硅煤的选煤工艺设计。煤质分析结果表明:邢美煤矿原煤内灰低、轻产物含量高且其中Fe2O3含量低,具备生产硅煤的可行性,而考虑到炼焦煤市场目前更加成熟,因此产品结构以炼焦煤为主,硅煤为辅;原煤中粗粒含量较高,其中研石含量也较高,可设置智能选研环节增强工艺对煤质的适应性,同时减少工人劳动强度;考虑硅煤及炼焦煤对产品粒度的要求,并兼顾破碎量及解离程度,分选上限宜为25mm或50mm,分选下限为0;原煤煤质较硬,按分选上限破碎时,粗粒级物料量较多,粒度组成有利于硅煤生产;生产硅煤时入料可选性等级为极难选,生产常规炼焦煤时,入料可选性等级大多为中等可选,且硅煤或炼焦煤的重选理论产率很高。工艺设计特点为:主选工艺采用脱泥有压给料三产品重介质旋流器分选,既可有效适应硅煤分选时的可选性,还可尽量避免无压给料重介质旋流器分选时精煤易夹带末研的问题,而且脱泥和三产品的工艺也有利于增强对煤质的适应性;采用先生产炼焦煤而后生产硅煤的生产工艺,有利于保证硅煤的灰分稳定,且有利于其脱介;主选三产品重介质旋流器一段为圆筒-圆锥形、负倾角布置,有利于扩大一、二段分选密度差,可满足该矿一段重介质分选生产炼焦煤时分选密度低,而二段重介质分选需排出纯研的要求,并适应轻产物产率高的煤质特性;脱介筛采用弧形筛+直线振动筛,且脱介筛设三道喷水及相应挡水坎,有利于脱介;大厅式布置,检修方便;预留多条可能煤流线,生产系统调整灵活。基于邢美煤矿煤质特点的产品结构制定和选煤工艺设计,有效满足了该矿生产硅煤的需求,同时有利于提高该矿的经济效益,对其他拟生产硅煤的企业也可起到一定的借鉴作用。

Called silicon coal for short,the industrial silicon coal is a product which places a high requirement on quality indicators and high in sale price.Through analysis of the coal samples collected from Xingmei Mine,the feasibility of producing silicon coal with the raw coal,as well as the product structure and the production process are affirmed and defined,and the design of the coal preparation process is finalized.As shown by analysis of the coal property,the raw coal is low in contents of inherent ash,volatile matters and FezO3,making it feasible to produce silicon coal;considering that coking coal has currently a more mature market,the produce mix of the mine's coal preparation plant should be made by predominately coking coal while making silicon coal subsidiary;as the raw coal contains a high percentage of coarse particles which is high in content of dirts,intelligent gangue removal separator can be used to enhance adaptability of coal preparation process and reduce labor intensity;considering the size requirement of both coking and silicon coal products,the upper size limit of separation should preferably be set at 25 mm or 50 mm and the lower size limit of separation is reduced to zero by taking account of the volume of size reduction and degree of liberation of raw coal;the raw coal is comparatively high in hardness,and when crushing is made according to the required upper size limit,the crushed coal contains a high percentage of coarser particles,which is conductive to the production of silicon coal;for producing silicon coal,the raw coal belongs to an extremely difficult-to-wash coal while for producing coking coal,the raw coal is a kind of moderately difficult-to-wash coal;and for producing either coking coal or silicon coal product using heavy-medium separation process,a very high theoretical yield can be gained.The designed coal washing process possesses the following special features:the pressure-fed 3-product heavy medium cyclone for treating dislimed coal is used as the primary washing equipment for higher adaptability to washability of feed coal,elimination of the problem of entrainment of fine dirts in clean coal product otherwise encountered with the use of gravity-fed H.M.cyclone,and higher adaptability to variation of raw coal property;the coal washing process of producing first coking coal and then silicon coal can help maintain stability of ash of product and facilitate medium draining operation;the primary H.M.cyclone's first stage is in a cylindrical-conical form and is arranged at a negative inclination angle,which is conducive to increase of difference of separation densities between the cyclone's first and second stages,and can meet the needs for producing coking coal through the first stage at a lower separating density,and for producing pure reject product through the second stage,as well as adapt to the raw coal property featuring a high yield of lighter materials;for medium draining,the sieve bend+linear vibrating screen draining process is applied,and the screens are arranged in a hall form and fitted with three rows of waters praying units and corresponding water-retaining dams for facilitating medium draining and maintenance of screen;several coal flow lines are reserved;and the entire washing system can be flexibly adjusted.The product structure and the coal preparation process designed based on analysis of raw coal property prove to be up to the requirements for the production of silicon coal and can bring about favorable economic benefits for Xingmei Mine.The work made in the paper may serve as a reference for other enterprises which are intending to produce silicon coal product.