Investigation of particles with high crack density produced by HPGR and its effect on the redistribution of the particle size fraction in heaps

The application of comminution technology such as the high-pressure grinding rolls (HPGRs), which is able to generate a high density of cracks in the ore particles, is favourable for leaching processes. Extraction of metallic values by the heap leach process, can take place on the particles with partial exposure of mineral grains, if it can provide sufficient surface front for chemical attack by leaching solution. The aim of this study was to assess the benefits of high crack density in the ore particles produced using the HPGR and how it could diminish due to inadequate percolation of the leaching agent.A zinc ore was comminuted using HPGR at three different pressure settings and with a cone crusher for the control experiment. Subsamples from the (+23/−25, +14/−16, +5.25/−6.75 mm) size fractions were characterized and packed into leach reactors. The reactors were stopped from time to time to investigate the progress of crack and micro-crack growth and its effect on metal extraction using the X-ray computed tomography (CT). The results are validated with those obtained using traditional techniques such as SEM and QEMSCAN. Investigation of the leach reactors residue indicated significant changes in the particle size distribution (PSD) of initial feed toward the fine size fraction. The residues from the reactors leaching the material prepared using the HPGR product contained more fine particles than the reactors, which were fed by cone crusher product. These differences were up to 10.3%.     

Leaching of a zinc ore and concentrate using the Geocoat™ technology

In this study, the Geocoat™ technology was used for the extraction of zinc from a mineral concentrate obtained from the Kooshk mine (Yazd, Iran) by a culture dominated by the mesophilic bacterium Acidithiobacillusferrooxidans in a packed column bioreactor. A low grade sphalerite ore was used as support for the concentrate coating. During the 100 days of leaching pH, Fe³⁺, Fe^total, microbial population density and zinc extraction were measured. The final zinc extraction from concentrate and low grade support was 97% and 78%, respectively, and it was found that leaching from the support does not proceed significantly before leaching from the coating is completed.     

Simulated small-scale pilot plant heap leaching of low-grade oxide zinc ore with integrated selective extraction of zinc

The leaching of low-grade oxide zinc ore and simultaneous integrated selective extraction of zinc were investigated using a small-scale leaching column and laboratory scale box mixer-settlers. Di-2-ethylhexyl phosphoric acid (D2EHPA) dissolved in kerosene was used as an extractant. The results showed that it was possible to selectively leach zinc from the ores by heap leaching. The zinc concentration of the leach liquor in the first leaching–extraction circuit was 32.57 g/L, and in the 16th cycle the zinc concentration was 8.27 g/L after the solvent extraction. The leach liquor was subjected to solvent extraction, scrubbing and selective stripping for the enrichment of zinc and the removal of impurities. The pregnant zinc sulfate solution produced from the stripping cycle was suitable for zinc electrowinning.     

加压氧化对锌渣氧粉中铟和锌浸出的影响

研究了含铟锌渣氧粉在加压和加入氧化剂的条件下与工业硫酸反应时,硫酸初浓度、浸出时间、反应温度、氧化剂用量等工艺条件对铟和锌浸出效果的影响。结果表明,加压和加入氧化剂高锰酸钾对锌渣氧粉中铟的浸出有较好的强化作用,能明显提高铟浸出率。其最佳工艺条件为:硫酸初浓度400g/L,反应时间120min,反应温度120℃,高锰酸钾用量为矿样量的4%。在此条件下,铟浸出率可达到90.6%。同时,加压氧化浸出工艺对锌渣物料中锌的浸出也有一定的强化作用。     

提高锌电积阳极泥中锰利用率的研究

研究了在硫酸介质中硫化铁直接还原浸出锌电积阳极泥中锰的工艺,重点考察了粒度、还原剂用量、初始酸度、浸出时间、浸出温度等对锰浸出率的影响,讨论了不同条件下的实验结果,确定了较佳的工艺参数.实验结果表明,在较佳条件下,可实现90％以上的锰浸出率,为提高锌冶炼过程中锰利用率提供了参考.     

Ferric sulphate/chloride leaching of zinc and minor elements from a sphalerite concentrate

Atmospheric leaching of a sphalerite concentrate in sulphate and chloride media was performed and the effect of several variables, such as solid/liquid ratio and oxidant (Fe(III)) concentration were investigated. The behaviour of minor elements, such as Cu, In, As, Sb, Bi, Sn and Pb, was also studied under different conditions. The results showed that using a solid/liquid ratio of 5% (w/v) it was possible to leach 95% of zinc after 2 h, with a solution of 0.5 M H₂SO₄ and Fe₂(SO₄)₃ at 80 °C. The minor elements As, Sb and Bi were also completely leached whereas copper leaching was favoured by the use of chloride medium. The oxidation of Fe(II) during the leaching tests was studied and an improvement of 20% zinc extraction was observed in an oxygenated system. Cross-current leach tests using two/three stages and a solid/liquid ratio of 10% (w/v) were performed to achieve 90% of zinc extraction. The electron microprobe analysis of the leaching residues showed no change on the sphalerite composition after the leaching, which indicates that the leaching of sphalerite involves the break down of the sulphide structure.     

湿法炼锌工艺过程除铁技术的发展

论述了常规法浸出、高温高酸浸出、硫化锌精矿直接加压浸出几种湿法炼锌工艺除铁过程的特点。指出硫化锌精矿直接加压浸出是一种能简化电锌生产工艺流程、降低单位产品能耗物耗、提高金属回收率的全湿法炼锌新工艺。     

硫酸浸出转底炉高锌铅粉尘的研究

研究了硫酸浸出转底炉高锌铅粉尘提取锌的工艺条件和参数。最佳浸出工艺条件为: 搅拌速度400 r/min, 硫酸浓度为1.0 mol/L, 浸出温度为25 ℃, 固液比为1∶8, 浸出时间为0.5 h。在此条件下, 锌的浸出率可达96%以上。采用针铁矿-氧化水解法除铁、过硫酸铵深度除铁锰、锌粉置换除杂的方法对浸出液净化处理, 得到高纯度硫酸锌溶液, 该溶液可直接电解制取锌或制取碱式碳酸锌和氧化锌。     

Iron solubilization during anaerobic growth of acidophilic microorganisms with a polymetallic sulfide ore

Acidithiobacillus ferrooxidans at 30 °C and Sulfobacillus thermosulfidooxidans at 47 °C were selected from a preliminary screening of various acidophiles for their ferric iron reduction capacities during anaerobic, autotrophic growth on sulfur. The selected cultures were used with a polymetallic sulfide ore under anoxic conditions to demonstrate enhanced solubilization of iron during leaching in shaken flasks and enhanced removal of iron from laboratory ore-leaching columns, compared to leaching with continuous aeration. Ore-associated, ferric iron-rich precipitates, which were formed under previously oxidizing conditions, were a potential influence on extraction of target metals and percolation through ore columns and were available as the source of ferric iron for anaerobic sulfur oxidation. Over twice as much iron was removed by moderate thermophiles when anoxic phases were introduced during the leaching. Enhanced removal of iron and some improvement in extraction of base metals from ore fragments were also demonstrated with a selected “Sulfolobus”-like strain during growth and leaching with alternating periods of aeration and anoxic conditions at 70 °C.     

Alkaline leaching of zinc from electric arc furnace steel dust

Electric arc furnaces (EAF) generate about 10–20 kg of dust per metric ton of steel, which constitute a hazardous waste, known as EAF dust. This dust contains a remarkable amount of non-ferrous metals, which include zinc, cadmium, lead, chromium and nickel that could be recovered, reducing the environmental impact of the leachable toxic metals, and generating revenue. In this paper, different alkaline leaching techniques were tested in order to dissolve the zinc present in an EAF dust: (i) conventional agitation leaching; (ii) pressure leaching; (iii) conventional leaching following a microwave pretreatment and (iv) leaching with agitation provided by an ultra-sonic probe. Temperature and sodium hydroxide concentration were the variables tested. The highest zinc recovery from the EAF dust, containing about 12% of zinc, was about 74%. This was achieved after 4 h of leaching in a temperature of 90 °C and with a sodium hydroxide concentration of 6 M of the leaching agent.     

机械活化铅锌烟尘强化硫酸浸出的工艺研究

以含铅锌烟尘为原料, 采用机械活化-硫酸浸出的湿法冶炼工艺分离铅锌烟尘中的金属铅及锌。着重研究了机械活化前后不同的硫酸浓度、液固比、浸出温度、浸出时间等工艺条件对原料中Zn浸出率及Pb入渣率的影响。实验结果表明, 机械活化前, H₂SO₄直接浸出铅锌烟尘的最佳工艺参数为H₂SO₄浓度175 g/L、液固比7∶1、浸出温度60 ℃、浸出时间60 min。在最佳工艺条件下, Zn浸出率达92.47%, Pb入渣率为90.30%。原料机械活化30min后, 最佳工艺条件变为H₂SO₄溶液浓度150 g/L、液固比5∶1、浸出温度50 ℃、浸出时间40 min。此时Zn浸出率达91.52%及Pb入渣率为95.36%。机械活化后铅锌烟尘的Zn浸出率及Pb入渣率对 H2SO4溶液浓度、液固比、浸出温度、浸出时间的依赖性明显降低。     

含锌高炉瓦斯泥浸出过程动力学研究

为研究高炉瓦斯泥硫酸浸出锌过程的动力学,以河北某高炉瓦斯泥为原料进行了硫酸浸出试验,分别考察了浸出温度、硫酸浓度对浸出过程锌浸出率的影响。随着浸出温度的升高和硫酸浓度的增加,锌浸出率逐渐提高,浸出速率降低。采用Avrami动力学模型对锌浸出过程进行模拟,结果表明,浸出过程符合n=0.160 4的Avrami动力学模型,反应表观活化能为10.02 kJ/mol,说明浸出过程受扩散控制,因此要提高浸出效率,应加强扩散效应。提高硫酸浓度或升高反应温度,加速了溶液中的反应过程和传质过程,锌浸出率提高。试验结果为湿法浸出过程动力学以及固废资源化利用后续研究和生产实践提供了一定的理论依据。     

渗滤浸出在抚州铀矿的生产应用

渗滤浸出生产工艺是针对我矿铀矿石性质复杂、矿石粘性大、易板结的特点而开发的,该工艺有效地解决了常规搅拌浸出成本高、堆浸又容易结垢板结、浸出率低的问题。2年的生产实践表明,铀浸出率达90%,与常规流程相比,动力消耗降低了60%,硫酸耗量降低27%,石灰耗量降低77%。     

酸浸-萃取法从炉渣中回收铜、锌的研究

以硫酸-双氧水浸出低品位炉渣, 有效回收了铜和锌。分别进行了pH值、温度、双氧水用量对炉渣中铜锌浸出率的影响研究。研究结果表明:在常压条件下, 当pH=2.5, 浸出温度70 ℃, 双氧水用量150 L/t时, 炉渣中铜和锌的浸出率分别为54.77%和72.33%。用P204作萃取剂, 硫酸作反萃剂, 得到铜回收率为84.97%, 锌回收率为96.47%。     

含铀煤灰焙烧球料渗滤浸出的研究

本文叙述了焙烧球料渗滤浸出的研究结果。重点讨论了各工艺参数对铀浸出率的影响，并测定了焙烧球料的机械强度对渗滤浸出操作的适应性。试验结果表明，在最佳浸出条件下，铀的浸出率可达97．8％，和搅拌浸出的结果相同。焙烧球料的机械强度也能满足渗滤浸出操作要求。     

锌焙砂浸出规律研究

本文以广西某地冶炼厂锌焙砂为原料,以硫酸为浸出剂,研究了不同硫酸浓度、不同浸出温度条件下,浸出时间对锌焙砂硫酸浸出过程中锌、铁浸出效果的影响规律;采用XRD分析方法,分析研究了锌焙砂及浸出产品中的物质存在形式。     

Characterisation Leaching Tests and Associated Geochemical Speciation Modelling to Assess Long Term Release Behaviour from Extractive Wastes

A pH dependent leaching test (CEN/TS 14429) and a percolation leaching test (CEN/TS 14405) developed in CEN/TC 292 have been used for the first time to characterise the release behaviour of different sulphidic mining wastes. Geochemical speciation modeling using LeachXS Orchestra provides another type of partitioning between mineral and sorptive phases than is currently practised in the mining industry. Comparing new leaching test data for seven tailings and two waste rock samples with model predictions gives new insights into release behaviour. In leaching, mineral transformations on the surface of waste rock or tailings particles, rather than bulk mineral composition, dictate release, which implies that mineralogical examinations are not necessarily relevant from a leaching perspective. Kinetic aspects of release from sulphidic waste can be addressed by testing material in different stages of oxidation or exposure to atmospheric conditions.     

难处理复杂氧化锌烟尘碱洗渣浸出试验研究

对铅冶炼难处理复杂氧化锌烟尘碱洗渣进行了"中性浸出—酸浸"工艺试验研究。结果表明,碱洗渣中性浸出时,锌、镉的浸出率先随浸出温度、液固比、搅拌速度和时间的增加而提高,后增速变缓;中浸渣酸浸时,液固比对锌、铟的浸出率无明显影响。锌、铟的浸出率随初始酸度、浸出温度和时间的增加先增加后变缓。中性浸出最佳条件为:温度338K、液固比5∶1、搅拌速度400r/min、浸出时间1h,此条件下,锌、镉的浸出率分别为80.3%和76.3%。中浸渣酸浸最佳条件为:初始酸度100g/L、浸出时间2h、浸出温度363K、液固比5∶1,在该条件下,锌、铟的浸出率分别为97.1%和85.5%。     

湿法炼锌净化渣碱浸提锌试验研究

采用碱浸法处理湿法炼锌净化渣, 研究了碱浓度、浸出时间、浸出温度、碱渣比等工艺参数对净化渣中锌浸出率的影响。结果表明, 适宜的碱浸条件为: 碱浓度300 g/L、浸出时间40 min、浸出温度110 ℃、碱渣比12 L/kg, 此条件下锌浸出率达95.8%, 实现了净化渣中锌的高效提取。     

响应曲面法优化含锌尘泥选择性浸出工艺

本文利用稀硫酸作为浸出剂,进行了从含锌尘泥中选择性浸出实验研究.采用SEM、XRD及EDS表征含锌尘泥原料以及浸出渣的结构和形貌,揭示锌选择性浸出行为.根据Box-Behnken实验设计原理,采用响应曲面法建立硫酸浓度、浸出时间、液固比及三者之间交互作用对锌浸出率影响的多元回归方程,对实验结果进行了ANOVA分析.在硫酸浓度为0.42 mol/L,液固比为7∶1、浸出时间为25.29 min,此条件下模型预测锌的浸出率达到95.58％.