钙镁碳酸盐碳化工艺设备选择及工艺条件控制

以石灰石、菱镁矿、白云石等非金属矿为原料,采用碳化法生产轻钙、轻质碳酸镁系列产品,对国内外碳化工艺及设备进行了比较,指出了某些操作中提高窑气CO2浓度、控制适宜反应温度及碳化终点的判断方法及特点等,进而说明碳化法具有生产成本低的优势,是国内外广泛采用此法的基础。     

Investigation of the potential for mineral carbonation of PGM tailings in South Africa

Increasing atmospheric CO₂ concentration is currently of considerable concern in terms of global warming. A possible technology that can contribute to the reduction of CO₂ emissions is its sequestration by mineral carbonation. In this study, tailings from several different platinum mines in South Africa will be mineralogically characterised and their potential for mineral carbonation reviewed. Mg and Ca-rich minerals (plagioclase, olivine, orthopyroxene, clinopyroxene) present in the tailings are good candidates for mineral carbonation, which mimics natural weathering processes in which these minerals react with gaseous CO₂ to form Ca or Mg carbonates. Since the reaction is influenced by particle surface area, the ultra fine grained nature of the PGM tailings provides another reason for the promise of PGM tailings for mineral carbonation. A preliminary ranking of the tailings samples and their efficacy for mineral carbonation has been developed according to whether the samples showed harzburgtic (e.g. Northam Platinum mine), pyroxenetic (e.g. BRPM) or noritic mineral assemblages. This information and understanding will assist in identifying opportunities and guiding the development of engineered facilities for the sequestration of CO₂ by means of mineral carbonation.     

超重力法合成立方形纳米级碳酸钙碳化过程研究

采用pH检测仪和电导率仪,TEM分析及粒度分布测试等对Ca(OH)2H2OCO2系统合成CaCO3的反应过程进行跟踪检测,结果发现:碳化反应前期,为CO2吸收控制,反应后期受Ca(OH)2溶解控制。立方形碳酸钙的形成,经历了由针状体变小,生成线束状中间体,经过葡萄串状形态,再断裂成粒径在15～30nm规整立方形晶体的过程。     

白云石加压碳化法制备碱式碳酸镁新工艺

研究了白云石加压碳化法制备碱式碳酸镁新工艺,其中包括煅烧、消化、碳化及重镁水常温分解4个反应阶段,具体分析了二氧化碳分压的大小对产品质量的影响。通过研究得到的工艺条件可显著提高碱式碳酸镁产品的质量。     

Enhancing Mg extraction from lizardite-rich serpentine for CO2 mineral sequestration

Carbon capture and storage by mineralisation (CCSM) is a promising technology that sequesters CO₂ from flue gases into stable mineral carbonates. Although the development of indirect pH swing processes (dissolution at acid pH and carbonation at basic pH) able to recycle the chemicals used are promising, there are still limitations in reaction rate of mineral dissolution being slow in view of a large deployment of the technology. The extraction of Mg from lizardite using magnesium bisulphate has been studied as a function of temperature, reagent concentration, solid to liquid ratio, thermal and mechanical pre-activation. Although the overall highest Mg extraction (95%) was obtained after 3 h, the reduction of the dissolution time to 1 h can consistently reduce the volumes to be treated per unit time leading to low capital costs in a hypothetical mineralisation plant. About 80% of Mg was extracted from lizardite in 1 h at 140 °C, 2.8 M NH₄HSO₄, particles <250 μm and a solid to liquid ratio of 100 g/l. At 140 °C, serpentine undergoes extensive structural modifications as indicated by XRD and FTIR analyses, producing amorphous silica and accelerating the kinetics of the reaction. Particles with diameter less than 250 μm were obtained by grinding the lizardite at 925 rpm for 10 min consuming 33 kW h/t_rock.     

以硫酸镁废液为原料制取轻质碳酸镁

以元江镍矿产出的硫酸镁废液为原料,采用硫酸镁—碳酸氢钠法进行了制备轻质碳酸镁的试验研究。结果表明:影响硫酸镁与碳酸氢钠反应的主要因素为反应时间、反应温度和硫酸镁的浓度。其最佳反应条件为Mg2+浓度1.25mol/L、反应温度75℃、反应时间180m in。在最佳条件下,产品中MgO的收率达90.42%,产品质量达到HG/T2959-2000合格品标准。     

硫酸盐法从锂云母制取碳酸锂的研究

锂云母经过配料、造球、焙烧、稀硫酸浸出，浸出液经净化、两次沉淀碳酸锂，浓缩结晶回收硫酸钠及硫酸钾钠复盐．获得技术经济指标是Ｌｉ２Ｏ总收率为８４．１％，其中Ｌｉ２Ｏ的直接收率为７９．９６％；碳酸锂的零级品率为８１．３６％，一级品率为１８．６４％．焙烧烟尘含氟经石灰水淋洗处理后可以达到排放要求．     

均相沉淀法制备碳酸锶粒子及其形貌控制研究

以八水氢氧化锶与尿素为原料采用均相沉淀法,通过添加控制剂合成不同形貌的碳酸锶粒子.结果表明:添加不同控制剂对粒子粒度和形貌具有一定的影响.通过电子显微镜和XRD表征表明,在没有添加控制剂时制备出了纺锤状和柱状的碳酸锶粒子,粒度分别为4～6um和2～3um,长径比分别约为6∶1和10∶1; 添加EDTA、三聚磷酸钠和硝酸铈等制备出了线状、棒状等碳酸锶粒子,粒子粒度明显减小.其晶体均属于正交晶系.     

低品位碳酸锰矿的选矿技术现状及进展

列举了我国低品位碳酸锰矿的各种选矿工艺路线,分析了各流程的特点,给出了各工艺参数和指标,认为生物法是降磷研究方向。     

氧化镁浆液碳化机理的研究

碳化是自白云岩或菱镁矿生产氧化镁和碱式碳酸镁等产品的基本工序。对碳化机理的研究有助于揭示碳化过程的本质和确定碳化的最佳条件,在理论和实践上均有意义。本文据系统的试验资料指出碳化的速控步骤不是化学反应,而是碳化过程中形成的 Mg(HCO_3)_2离开 MgO 固体表面向溶液的扩散。可作为判据的反应活化能计算结果(0.997kJ/mol)亦为此提供了证明。     

超细重质碳酸钙干法生产工艺分析

本文综合比较了超细重钙干法加工工艺中常见设备的应用状况。从设备性能与实际生产技术参数的角度对常见的系统工艺进行比较分析,结果表明球磨配分级系统工艺在生产超细重钙中具有明显的优越性。     

海港码头混凝土暴露26年的碳化情况分析

混凝土碳化对钢筋混凝土结构的耐久性有很大的影响,破坏钢筋表面的钝化层,使混凝土失去对钢筋的保护作用。本文分析了混凝土碳化的机理,用酚酞试剂确定碳化区的深度,然后再用数字压力测量器测定试件的CaCO3含量,来进行碳化深度分析,并探讨了部分碳化区与碳化深度的关系。     

年产5万t超细重钙生产线的设计实践

本文介绍了四川石棉巨丰粉体有限公司年产5万t超细重钙干法生产线的设备选型、研磨设备的改进及其系统生产工艺的优化。生产实践表明:有效减少了系统过研磨、提高了研磨效率和分级效率。     

超细碳酸钙的碳化机理研究

间歇鼓泡碳化法生产超细碳酸钙的碳化过程是一个四相浆态反应过程。在双膜理论基础上,首次提出用“四膜模型”的观点来探讨碳化各阶段的动力学区域和碳化机理;揭示了包裹返碱现象发生的规律,完善了碳化过程的化学理论基础。     

Acoustic emissions simulation of tumbling mills using charge dynamics

Knowledge of the internal variables of a mill is of importance in design and performance optimization of the mill, notwithstanding the difficulty in measuring these variables within the harsh mill environment. To overcome this problem, the research has focused on measuring the internal parameters through non-invasive measurement methods such as the use of the vibration/acoustic signal obtained from the mill. Alternatively, virtual instruments, such as discrete element methods (DEM), are employed. Here, a methodology is developed to simulate on-the-shell acoustic signal emitted from tumbling mills using the information extracted from a DEM simulator. The transfer function which links the forces exerted on the internal surface of the mill and the acoustic signal measured on the outer surface is measured experimentally. Given this transfer function and the force distribution obtained from the DEM simulation, and assuming a linear time-invariant response, the on-the-shell acoustic of a laboratory scale ball mill has been simulated. Comparison of this simulated signal with the signal measured experimentally can be used as a criterion to judge the validity of the DEM simulations, and as a tool for enhancing our understanding of both DEM simulations and the use of acoustics within the context of mineral processing. The results derived from preliminary experiments on a laboratory scale mill shows satisfactory agreement between the actual measurement and the simulated acoustic signal.