铁矿浆过滤回水管道结垢物形成机制

国内A选矿厂使用R31助滤剂代替部分硫酸助滤剂对铁矿浆进行过滤脱水,发现滤液回水管道形成明显的结垢物。为查明结垢物形成的化学反应原理,通过X射线衍射分析确定了结垢物物相为碳酸钙。采用荧光分析法对不同滤液的元素组成进行定量分析,同时结合碳酸钙生成模拟实验,结果表明,R31滤液与硫酸滤液混合后,CO_3~(2-)与Ca~(2+)反应生成CaCO_3沉淀。CO_3~(2-)来源为R31助滤剂滤液中羧基(-COOH),其在碱性条件下发生脱羧反应产生CO_2,CO_2遇水生成CO_3~(2-);Ca~(2+)的来源为过滤时硫酸与铁矿物中的含钙物质发生反应形成大量的Ca~(2+)。最终,揭示了铁矿浆过滤回水管道结垢物形成的化学反应机制。     

废铁屑还原软锰矿制备高纯硫酸锰工艺研究

研究了采用废铁屑作为还原剂,在稀硫酸介质中湿法还原软锰矿制备硫酸锰的工艺过程。通过单因素实验确定最佳工艺参数,结果表明：当Fe/MnO2的摩尔比为0.78∶1,H2SO4/MnO2的摩尔比为2.1∶1,反应温度50℃,反应时间80 min时,锰的浸出率在95%以上。加入碳酸钙中和调节溶液pH值至5~6,使溶液中的铁、铝等杂质离子水解为氢氧化铁、氢氧化铝等沉淀除去,加入硫化钡使浸出溶液中的重金属离子以硫化物沉淀除去,减压过滤得到硫酸锰粗滤液,向粗滤液中加入二氟化锰使溶液中的Ca2＋、Mg2＋等离子生成氟化物沉淀,然后溶液经过静置过滤得到硫酸锰净化液,滤液经浓缩、结晶制备硫酸锰产品。经检测产品纯度在99%以上,杂质含量低于国家标准。     

VN推板窑窑腔内结垢原因

对VN的生产以及推板窑窑腔内大量烟垢的形成分别进行了热力学研究。热力学计算表明,温度超过1 400 K时,V2O3与碳反应生成VC和CO气体。温度在1 400~1 600 K时,VC与氮气反应生成VN,钾、钠氧化物与副产物CO气体反应生成碳酸盐。实验研究表明,温度高于1 000 K时烟垢烧结失重率变化明显,窑腔内第5、6温区的实际温度有利于碳酸盐的形成,最终碳酸盐在这些温区形成烟垢。形成烟垢的CO气体和钾、钠化合物主要来自高温区。在第7、8温区增设排烟口将会有利于烟气排除,避免窑腔内结垢物的生成,对实际生产有指导意义。     

碳酸钠在氧化铅浮选中的研究与应用

某氧化铅浮选矿浆中含有大量的可溶性盐,致使矿浆中的Ca2+浓度增大并转化为碳酸钙覆盖在碳酸铅矿物表面,阻碍碳酸铅的硫化。添加碳酸钠,使Ca2+预先沉淀,有利于碳酸铅的硫化,同时提高捕收剂与碳酸铅作用的机率,改善浮选矿浆环境,从而有效地提高氧化铅的回收率。     

固态下SiO2对二元铁酸钙形成过程的影响

 铁酸钙作为高碱度烧结矿黏结相的主要组成,其形成受SiO2的影响,但到目前为止,其影响机理尚不是十分明确。通过XRD和矿相显微镜观察,并结合Rietveld法定量分析,研究了SiO2对二元铁酸钙形成过程的影响。结果表明：Fe2O3与CaO反应,700 ℃时形成Ca2Fe2O5,在800 ℃时出现CaFe2O4,随着温度升高,Ca2Fe2O5逐渐向CaFe2O4转变。SiO2存在时,在铁酸钙形成过程中有Ca2SiO4生成,温度低于900 ℃时,受动力学条件的影响,反应速率较低,Ca2SiO4的量相对较少,另外,SiO2的阻碍作用随其质量分数的增加而增强,进而导致已形成的Ca2Fe2O5与Fe2O3未能继续反应形成CaFe2O4而使其质量分数逐渐增多;高于900 ℃时,随着温度的升高,动力学条件改善,离子扩散能力增强,其中,Fe3+通过CaFe2O4层比Ca2+通过Ca2Fe2O5层更容易,进而促进了CaFe2O4形成反应的进行,Ca2Fe2O5向CaFe2O4转变,但随着SiO2质量分数增加,Ca2SiO4的生成量增多,CaO与Fe2O3的接触面积减小,抑制了CaFe2O4的生成。     

白云石与氟磷灰石的浸出过程热力学

根据化学位图绘制基本原理和方法,分析了Mg2+-Ca2+-H2CO3-H2O、CaCO3·MgCO3-SO2-4-H2O、Ca2+-F--H3PO4-H2O、Ca5(PO4)3F -SO2-4-H2O和Mg2+-H3PO4-H2O体系在常温下的热力学平衡,研究了Ca-Mg-P-H2SO4体系在常温下的溶液-矿物溶解、沉积条件,形象、直观地描述了该溶液体系化学平衡条件及反应进行的限度,为磷矿选矿和湿法浸出过程提供理论依据.结果表明:硫酸可以促进白云石和氟磷灰石的溶解,溶解产物主要是Mg2+、H3PO4,其次是H2PO-4,固相产物主要是硫酸钙晶体;氟磷灰石溶解过程中产生的磷酸在酸性条件下不与溶出的Mg2+反应形成Mg3(PO4)2.     

降低高酸高铟预中和石膏渣含铟量的工艺研究

湿法炼锌赤铁矿法回收铟的主要工艺流程为利用二氧化硫还原浸出低酸浸出渣中的铟，还原浸出后液酸度约30 g/L,需要预先中和使酸度降至10 g/L,然后加入碳酸钙中和沉铟、富集铟，沉铟渣经浸出、净化、萃取等工艺流程回收铟。预中和过程中产生的石膏渣会夹带部分铟，造成铟的损失。本文通过进行单因素试验，研究预中和液中Fe³⁺浓度、终点酸度及反应时间等试验条件变化对预中和石膏渣含铟量、石膏渣沉降及过滤性能的影响。试验结果表明，由于In³⁺与Fe³⁺性质相似，在黄钠铁矾形成过程中，In³⁺可部分取代Fe³⁺形成晶间化合物进入渣中，因此Fe³⁺含量越高，预中和石膏渣含铟量越高；终点酸度小于10 g/L时，溶液中的Al、Si易生成胶状物，与Ca化合生成钙铝黄长石沉淀，影响矿浆沉降性能及过滤性能，终点酸越低，石膏渣含铟量越高，过滤性能越差；随着反应时间的延长，溶液中Fe²⁺氧化成Fe³⁺的量越多，石膏渣含铟量逐渐增加。     

基于针铁矿法对石棉尾矿酸浸液高效除铁

石棉尾矿酸浸分离制备系列高纯硅镁化合物粉体材料是石棉尾矿高值化利用的重要途径,但石棉尾矿的酸浸液中除主要含有Mg2+外,还含有如Fe3+、Fe2+等杂质离子。以石棉尾矿经焙烧、酸浸后的高镁酸性滤液为原料,氨水为中和剂,对滤液进行沉淀除铁,采用分光光度法测定滤液中铁离子的浓度,XRD、FT-IR等分析沉淀产物的物相结构变化。结果表明,在反应终点pH=4.5、反应温度80 ℃、反应时间10 min条件下,沉淀物主要由针铁矿和黄铵铁矾构成,铁的去除率可达99.71%,镁损失率仅为3.39%,悬浊液的过滤速度为3.46 mL/min,产物过滤性能好,铁离子去除率高。     

推板窑窑腔结垢的机理研究及预防

生产氮化钒用推板窑在使用过程中极易在窑腔内形成结垢,当结垢物长大到一定程度后会影响推板窑生产。分析了氮化钒的反应机理及结垢物的化学成分,对氮化钒的结垢机理进行了研究,结垢物是由碳、K_2CO_3、Na_2CO_3、水等形成的混合物。减少生料球内的残存水分和入窑生球粉料量,可以有效控制结垢物的形成,延长推板窑的使用寿命。     

铅锌矿中铅锌快速连续测定

采用盐酸、硝酸、硫酸分解试样,铅形成硫酸铅沉淀而与锌分离.以慢速滤纸过滤,滤液用EDTA络合滴定分析法测定锌量;沉淀以HNO3(1+1)溶解后,在pH5.5～6.0的乙酸-乙酸钠缓冲溶液中,以二甲酚橙为指示剂,用EDTA标准溶液滴定铅量.     

Application of Surface Chemical Fundamentals to Improving Industrial Filtration Rates

The throughput of any process is limited by the step with the lowest throughput. In iron ore processing, filtration is used to dewater the iron ore concentrate created during reverse flotation. The conditions of the reverse flotation of iron ore and the efficient filtration of iron ore concentrate are found to be at odds with each other. We show that optimizing the filtration conditions should reduce cation retention in the filter cake, which also improves pellet quality in laboratory scale work. Experimental work was performed to investigate potential implementations at plant scale. Based on data collected at operating magnetite concentrators, it has been found that adding CO₂ into the filter slurry can increase filtration rates dramatically. In plant scale work, filtration rates were increased by up to 23.7% with the addition of 0.54kg of CO₂/ton of feed. We compare these results with laboratory scale results on the same process and elaborate on the theory leading to this discovery, while considering its potential impact on final pellet and iron product quality.     

WATER CHEMISTRY EFFECTS IN IRON ORE CONCENTRATE AGGLOMERATION FEED

ABSTRACT

In two different iron ore processing plants, it was demonstrated that when magnetite concentrate was filtered to prepare it for use as pelletization feed, the moisture that remained in the filter cake had greatly elevated levels of cations compared to the water removed by the filtration process. In particular, calcium concentrations in the filter cake were 565 times higher than in the filtrate water in Plant 1 and 19.4 times higher than the filtrate water in Plant 2. This effect is due to the adsorption of divalent cations on the magnetite surfaces resulting from electrostatic attraction when the pH of the solution is in the range where magnetite has a negative Zeta potential. Measurements of the Zeta potential as a function of pH for magnetite from Plant 2 determined that its point of zero charge (PZC) occurred at pH 3.0 to 3.5, which was much lower than is commonly reported in the literature and demonstrates that the PZC for magnetite is much more variable than is commonly thought. Plant experiments were carried out using carbon dioxide to reduce the pH of filter slurry so that the PZC could be approached. This was intended to allow adsorbed cations to be released from the magnetite surfaces during filtration. The pH adjustment was demonstrated to improve filtration rates by as much as 23%.     

Aqueous Ions in Process Water and Cake Moisture During Iron Ore Filtration

In mineral beneficiation plants, aqueous ions from the process water concentrate within the filter cake moisture. These high concentrations of ions can lead to operational issues during downstream processes. This paper examines the ionic content of iron ore slurry before it was filtered at an operating hematite beneficiation plant and compared it with the ionic content of the moisture in the resultant filter cake. Water analyses were conducted to determine the sodium, potassium, calcium, magnesium, fluoride, chloride, nitrate, nitrite, carbonate, sulfate, and phosphate concentrations in both filter feed slurry and filter cake moisture. Results have shown that all tested ions within the process are more concentrated within the filter cake moisture than in the filter feed slurry. This has been attributed to the physical and chemical interactions of these ions with the iron ore particle surfaces. Of these ions, phosphorus concentrates most with the filter cake moisture content having a phosphorus content that is 24.67 times that of the filter feed slurry.     

硅酸盐对红土镍矿焙烧料酸浸过滤的影响

通过对浸出条件的改变,考察了不同硅酸盐浓度对红土镍矿焙烧料酸浸浆体过滤性能的影响。发现当滤液中硅酸盐浓度大于7.5 g/L时,酸浸浆体的过滤性能急剧下降。研究表明:当酸矿比为1.0、液固比10∶1、反应温度70℃、反应时间90 min时,红土镍矿焙烧料Co、Ni、Fe2+的浸出率均可达90%以上,滤液中硅酸盐浓度为6.66 g/L,浆体过滤性能良好。     

高硅氧化锌矿硫酸浸出的工艺及机理研究

通过研究硫酸浓度、中和速度及搅拌强度对矿浆沉降过滤性能及矿石中相关元素浸出率的影响,全面细致地阐述高硅氧化锌矿硫酸浸出工艺的机理,分别针对浓酸浸出和稀酸浸出工艺中普遍存在的问题和不足,讨论微波新技术引入湿法炼锌过程的必要性和可行性。     

Microstructure Characteristic and Phase Evolution of Refractory Siderite Ore during Sodium-carbonate-added Catalyzing Carbothermic Reduction

Thermodynamic analysis of refractory siderite ore during carbothermic reduction was conducted.Microstructure characteristics and phase transformation of siderite ore during sodium-carbonate-added catalyzing carbothermic reduction were investigated.X-ray diffraction(XRD),scanning electron microscopy and energy-dispersive analysis of X-rays were used to characterize the reduced samples.Results indicate that the solid reaction between FeO and SiO_2 is inevitable during carbothermic reduction and the formation of fayalite is the main hindrance to the rapid reduction of siderite.The phase transformation of present siderite ore can be described as:siderite-magnetite-metallic iron,complying with the formation of abundant fayalite.Improving the reduction temperature(≤1 050 ℃)and duration is helpful for the formation and aggregation of metallic iron.The iron particle size in the reduced ore was below 20μm,and fayalite was abundant in the absence of sodium carbonate.With 5% Na_2CO_3 addition,the iron particle size in the reduced ore was generally above 50 μm,and the diffraction intensity associated with metallic iron in the XRD pattern increased.The Na_2O formed from the dissociation of Na_2CO_3 can catalyze the carbothermic reduction of the siderite.This catalytic activity may be mainly caused by an increase in the reducing reaction activity of FeO.     

滴定法连续测定铅锌矿中铅锌铜

铅锌矿样经盐酸和硝酸溶解后,以硫酸为沉淀剂,使铅与硫酸形成硫酸铅沉淀,锌和铜留在溶液中。过滤后,用乙酸-乙酸铵缓冲溶液溶解硫酸铅沉淀,以二甲酚橙为指示剂,EDTA标准溶液滴定铅。分取两份滤液,一份用于测定锌,另一份用于测定铜。测定锌时以氢氧化物沉淀分离铁、锰等金属离子后,在pH 5.5乙酸-乙酸钠缓冲液中,硫脲存在下,以二甲酚橙为指示剂,用EDTA标准溶液滴定锌。另一份滤液中铜采用碘化钾-硫代硫酸钠滴定法测定。方法用于铅锌矿样品中铅、锌和铜的测定,测定值与国家标准方法的测定值一致,测定结果的相对标准偏差在0.042%～0.088%之间。     

影响酸法加压铀浸出矿浆过滤的因素及改善方法研究

研究了矿浆浓度、浸出温度和压力、金属离子浓度、胶体物及矿石粒度等因素对铀酸法加压浸出矿浆过滤性能的影响,以及改善其过滤的方法。试验发现,在满足铀浸出率要求的条件下,三价铁的结晶形态和在溶液中的浓度是影响矿浆过滤速度的最关键因素。     

铁精矿浆体管道输送特性研究

根据多种铁精矿浆体管道输送试验研究结果,对铁精矿浆体的特性、管道输送参数、管壁磨蚀试验研究结果进行综合分析、探讨,获得了铁精矿浆体管道输送的一些规律,为输送管道的设计提供了参考。     

红土镍矿资源全回收新工艺及清洁生产分析

对红土镍矿进行高酸浸出,浸出滤液加入硅镁镍矿预中和,预中和滤液加入菱镁矿中和结晶除铁,除铁滤液加入菱镁矿沉镍,沉镍滤液浓缩结晶高纯硫酸镁,高纯硫酸镁生产下游高纯镁产品,除铁渣用于炼铁;浸出渣、预中和渣用于生产白炭黑的工艺．实现红土镍矿资源全回收．