硫酸铵强化石膏溶解矿化制备高纯CaCO_(3)

近年来,利用固废石膏矿化CO_(2)联产CaCO_(3)及硫酸铵工艺技术受到广泛关注,然而由于固废石膏成分复杂,分离纯化困难,成本与矿化产品品质难以兼顾导致其无法大规模工业化利用。为此,以硫酸钙及磷石膏为原料,提出以石膏矿化液相产物硫酸铵溶液强化硫酸钙溶解浸出,液固分离后再进行矿化的间接矿化工艺。试验研究了溶解强化过程中硫酸铵浓度及溶解浸出时间对硫酸钙溶解特性的影响,以及矿化过程中氨水浓度、温度、矿化反应时间等因素对矿化过程和矿化产物的影响。确定了优化的溶解与矿化工艺条件,基于此,进一步研究磷石膏的间接矿化过程,结果表明,与直接矿化相比,间接矿化可使CaCO_(3)产品纯度由82.2%提高至98.6%,且产品粒度D_(50)由22.00μm降至10.98μm。间接矿化工艺可有效强化石膏溶解浸出过程,避免引入外加介质,并制备高纯度轻质CaCO_(3),相关研究可为固废石膏矿化CO_(2)技术的经济应用提供基础支持。

氧化铌的硫酸溶解机理研究

研究Nb2O5在硫酸中的溶解过程,利用溶解热力学相图,结合前期试验结果确定了氧化铌的溶解产物;通过测定H2SO4-Nb2O4SO4-H2O溶液体系电导率研究了Nb2O5在硫酸中的强化溶解机理。结果表明,溶解产物Nb2O4SO4在溶液中是以稳定的配合形式存在的,稳定常数为572,根据配位溶解理论说明配位促进了Nb2O5在酸中的溶解。

高密度脉冲电流处理对6N01铝合金组织和性能的影响

探讨了电流密度对6N01铝合金晶粒、拉伸性能、硬度和强化相的影响。结果表明,试样经150、200、250A/mm2的脉冲电流处理后均发生晶粒细化,电流密度为200 A/mm^(2)时,晶粒的细化效果最好。随着电流密度的增大,6N01铝合金塑性逐渐增加,强度和硬度逐渐下降。电流密度为250 A/mm^(2)时,原始态的伸长率由12.3%增长至13.6%,屈服强度由254.6 MPa降至117.3 MPa,抗拉强度由286.3 MPa降至190.9 MPa,硬度由87 HV降至53 HV。电流密度和处理时长均对Portevin-Le Chatelier(PLC)效应存在影响,电流密度越大或处理时长越长,PLC效应越显著。高密度脉冲电流处理可导致强化相快速溶解,且溶解程度随电流密度的增加而增大。

Intensifying gibbsite precipitation from sodium aluminate solution by adding a mixed seed

Gibbsite precipitation from sodium aluminate solution was intensified by adding mixed industrial and self-prepared active seeds,and its mechanism was researched preliminarily.The interfacial properties of seed/aluminate solution were determined for separate industrial and active seed.Contact angles of seed/aluminate solution and the specific surface area of seeds were respectively measured by sessile drop and BET method,and the morphology and particle size of precipitates were recorded by SEM and laser diffraction.The results show that,compared with the industrial seed,the active seed has a better wettability,lower interfacial tension,and larger specific surface area,being conducive to enhancing gibbsite precipitation from sodium aluminate solution.SEM analysis of the precipitates indicates that the embedment and accumulation/agglomeration of extremely fine particles on the surface of coarse industrial seed can effectively control the content of fine particles in the precipitation product.With extra 3.1–4.6 g/L active seed,the gibbsite precipitation ratio was increased by 3.23%–3.92%.Moreover,the mass percentage of particles<45μm in precipitation product has even a slight decrease compared with that for the traditional precipitation product or of the industrial seed itself.The result presented is favorable to developing an intensified gibbsite precipitation process for commercial alumina manufacture.

花马池盐湖“开渠引渗—强化溶盐”滩晒盐制卤工艺

除天然降水外，引机井水和处理后的工业废水做为水源溶盐制卤；在盐湖中部开挖溶盐渠引水溶解盐湖上部盐层，使用自制溶盐器配合采盐船强化溶解；在溶盐渠两侧平行开挖集卤渠，收集溶盐渠渗流溶盐水和周边潜卤水，抽卤灌池晒盐，构成完整可靠的本盐湖溶解采矿工艺系统。