复合煤泥浮选剂的制备及其应用

利用酒厂酿酒残液为主要原料,加入一定的轻柴油、有机酸,制备了性能优良的复合煤泥浮选剂.研究了复合煤泥浮选剂的制备工艺条件对浮选剂浮选性能的影响.结果表明,复合煤泥浮选剂制备的适宜条件为:轻柴油用量为酿酒残液质量6%,有机酸用量为酿酒残液质量2%,轻柴油和有机酸的加热温度为80℃,轻柴油、有机酸与酿酒残液在常温下的反应时间为60min.采用该种浮选剂用于煤泥的浮选试验,该种浮选剂不仅浮选效果好,对不同煤质的适应性强,而且成本低廉.

复合型煤泥旋流器流场模拟

简要分析了目前选煤厂常用的煤泥洗选工艺,并提出了一种新型的复合型煤泥旋流器;介绍了复合型煤泥旋流器的结构及工作原理,利用Fluent软件对复合型煤泥旋流器流场进行了模拟,分析了复合型煤泥旋流器不同空间内的流体切向速度、轴向速度及径向速度,得出复合型煤泥旋流器内存在较大的切向速度、轴向速度及径向速度,为煤泥在径向上分层及轴向上分离提供了动力,复合型煤泥旋流器在同一时段内既完成细煤泥分级又完成粗煤泥分选是完全可行的,可进一步进行实践试验研究。

复合型煤泥旋流器分级分选效果试验研究

为研究复合型煤泥旋流器的分级分选效果,介绍了复合型煤泥旋流器的结构,分析了复合型煤泥旋流器的工作原理,在对复合型煤泥旋流器流场数值模拟研究结论的基础上,对先分级后分选和先分选后分级2种复合型煤泥旋流器结构进行设计,并对分级分选效果进行了试验研究。结果表明:2种复合型煤泥旋流器都有明显的分级和分选效果,先分级后分选结构复合型煤泥旋流器分级分选效果优于先分选后分级结构复合型煤泥旋流器,旋流器最佳结构参数和操作参数有待后续试验进一步完善。

非磁性物对重介质悬浮液旋流稳定性及分选效果的影响

低密度重介质悬浮液存在强沉降失稳趋势,可能造成旋流器分选富集镜质组的效果变差。以低灰煤泥、蒙脱石及其混配的复合煤泥作为非磁性物,进行了重介质分选试验,探讨重介质悬浮液中非磁性物含量及组成对其旋流场稳定性和实际分选效果的影响,结果表明:随非磁性物含量的提高,悬浮液底流浓缩度、溢流澄清度、浓缩效率及底溢流密度差均下降,稳定性提高,且添加复合煤泥具有更好的稳定性;仅添加蒙脱石时悬浮液的浓缩效率值和溢流澄清度均高于不添加非磁性物的悬浮液,表明悬浮液体系更加不稳定;悬浮液中复合煤泥含量为30%和40%时,可以分选得到灰分小于3%且镜质组含量高于75%的目标精煤,分选的可能偏差E值最低达到0.034g/cm~3,而在其含量超过50%,或仅添加低灰煤泥或蒙脱石的悬浮液均未能达到此要求;添加过多的非磁性物后虽然可以进一步提高悬浮液稳定性,但也会对分离过程中被选煤颗粒在旋流器中的迁移运动产生更大的阻碍作用从而使分选效果变差,因此悬浮液中非磁性物含量存在最佳值。

Consolidation analysis of composite foundation with partially penetrated cement fly-ash gravel(CFG) piles under changing permeable boundary conditions

Based on the double-layered foundation theory, the composite ground with partially penetrated cement fly-ash gravel(CFG) piles was regarded as a double-layered foundation including the surface reinforced area and the underlying untreated stratum. Due to the changing permeability property of CFG piles, the whole consolidation process of the composite ground with CFG piles was divided into two stages, i.e., the early stage(permeable CFG pile bodies) and the later stage(impermeable pile bodies). Then, the consolidation equation of the composite foundation with CFG piles was established by using the Terzaghi one-dimensional consolidation theory. Consequently, the unified formula to calculate the excess pore water pressure was derived with the specific solutions for the consolidation degree of composite ground, reinforced area and underlying stratum under instant load obtained respectively. Finally, combined with a numerical example, influencing rules by main factors(including the replacement rate m, the treatment depth h1, the permeability coefficient Ks1, Kv2 and compression modulus Es1, Es2 of reinforced area and underlying stratum) on the consolidation property of composite ground with CFG piles were discussed in detail. The result shows that the consolidation velocity of underlying stratum is slower than that of the reinforced area. However, the consolidation velocity of underlying stratum is slow at first then fast as a result of the transferring of effective stress to the underlying stratum during the dissipating process of excess pore water pressure.

Effective Utilization of Coal Fly Ash in Building Material Production

This paper is aimed at verifying utilization possibilities of alkaline modified coal fly ash as cement replacement in the concrete. The influence of alkaline activated coal fly ash originating from Slovakian power plant in Novsky （Si/Al = 3,1） as a partial cement replacement in concrete on compressive strength of hardened composites after 28 and 90 days was investigated. Alkaline activation of coal fly ash was realized in an autoclave at 130 ℃ and pressure of 160 kPa during 5 hours and in a reactor under normal conditions （equal temperature during 36 hours） at solid/liquid ratio of 0.5. Coal fly ash/cement mixtures were prepared with 25 % cement replacement by starting and modified coal fly ash and given in forms. Compressive strengths of composites after 28 and 90 days of hardening were compared to referential composite without coal fly ash and evaluated according to the standard of STN EN 450 by the value of relative strength KR （compressive strength of coal fly ash/cement composite to compressive strength of comparative concrete）. The final compressive strengths of hardened composites based on alkaline activated coal fly ash reached values in the range of 6 up to 50 MPa. In the set of experimental composites based on alkaline activated coal fly ashes, the highest value of relative strength after 28- and 90- days of hardening reached composite with cement replacement by coal fly ash zeolitized in autoclave （105% of compressive strength of referential sample）, what is connected with formation of zeolitic phases on surface of coal fly ash particles. The achieved results confirm that alkaline activation of coal fly ash in an autoclave under observed conditions can be successfully used as a partial cement replacement in concrete of C20/25 and C25/30 in accordance with requirements of standards （STN EN 450 and STN EN 206）.