The characterisation and behaviour of carbonaceous material in a refractory gold bearing ore

Sulfide ore and a flotation concentrate from Fosterville contained 0.76% carbonate carbon, 0.18% native carbon and 0.20% organic carbon of which 4.5 ppm were n-alkane hydrocarbons. The concentrate yielded 0.99% native carbon, 0.28% carbonate carbon and 0.11 % organic carbon of which 19.7 ppm was n-alkane hydrocarbons. IR spectroscopy of the fulvic acid fraction of the flotation concentrate showed it to be similar to humic acid.The addition of representative levels of n-alkane hydrocarbons, carbonate carbon and humic acid to the oxidised ore indicated that these components had negligible effect on gold recovery. The addition of 0.2% native carbon decreased gold recoveries from 84.4% to 68.8% while 0.2% activated carbon reduced recovery to 3.1%. Native carbon when acidified, mimicking the environment of bacterial oxidation, resulted in recovery dropping from 84.4% to 61.0%.Gold recovery for a standard sulfide float was 92.5%. Sodium naphthalene sulfonate (SNS) was the only depressant to lower native carbon levels in the concentrates without reducing gold recovery. 275 g/t SNS depressed 45% of the native carbon and gold recovery was unchanged. Nitric acid oxidation and subsequent cyanidation of the SNS concentrates lead to overall gold recovery improving from 88.3% for a standard sulfide float to 92.0%.     

苏丹某低品位金矿石柱浸-活性炭吸附试验研究

苏丹某金矿为低品位贫硫石英脉型金矿,金主要赋存于脉石矿物粒间,以中、粗粒级嵌布为主。为给该矿石的开发利用提供依据,对其进行了柱浸-活性炭吸附试验研究。结果表明：在给矿粒度为-20 mm、浸液pH=10.5～11、氰化钠浓度为0.10%、喷淋强度为20 L/(m2·h)、喷淋时间为16 d时,金的浸出率可以达到73.51%。对活性炭A和活性炭B进行磨损试验和饱和吸附容量对比试验,结果显示活性炭A综合吸附性能更好。在活性炭A投加量为8 g/L、吸附时间为20 h时对浸液进行金吸附试验,金的吸附率可以达到99.67%。试验结果可以为该金矿资源的开发利用提供技术依据。     

Study on the pyrolysis behavior of Shendong Shangwan coal and its macerals concentrate

The pyrolysis characteristics of Shendong Shangwan coal and its macerals concentrate were investigated using thermogravimetry (TG) coupled with mass spectrometry (MS). The evolved gases were analyzed online by MS spectroscopy. The results of TG/DTG (derivative thermogravimetry) show ths vitrinite concentrate has greater weight loss rate and higher volatile yield than the other two samples. More light hydrocarbons C₁-C₅ are released from the vitrinite concentrate than from the Shendong Shangwan coal and inertinite concentrated in the process of pyrolysis. Three samples have similar shape curves of evolved gases of C₂–C₅ with different intensities. When the pyrolysis temperature was lower than 418 °C, the amount of C₆H₆ evolved in the process of pyrolysis of inertinite concentrated was higher than that of raw coal and vitrinite concentrate. As the temperature rising, the production rate of C₆H₆ increased. Below 672 °C, C₆H₆ evolution rate of vitrinite concentrate was far greater than the other two samples; the main evolution temperature range of C₇H₈ was 400 °C to 700 °C for the three samples. The amount of H₂ and H₂O released first increased and then decreased with the temperature increase while more H₂ released for pyrolysis of inertinite concentrated and more H₂O released for the pyrolysis of vitrinite concentrate.     

Fungal pretreatment of sulfides in refractory gold ores

This study assessed the capability of the fungus, Phanerochaete chrysosporium, to decompose pyrite, arsenopyrite and a sulfide-containing flotation concentrate in an effort to develop a microbial process for pretreating refractory gold ores. The extent of biotransformation was monitored by analyzing for iron, sulfur and arsenic in incubation solutions, and for sulfide sulfur in the residual solids. The results were then expressed as percentages of the initial weights. For arsenopyrite, 1.5 wt.%, 7.2 wt.% and 10.3 wt.% of iron, arsenic and sulfur respectively were present as soluble constituents in the incubation solution within 21 days of fungal treatment, whereas for pyrite, there was 1.2 wt.% iron and 6.0 wt.% sulfur. For the same processing period in the case of the flotation concentrate, 1.8 wt.%, 6.1 wt.% and 10.7 wt.% respectively of iron, arsenic and sulfur remained in solution. Overall, the decomposition of sulfide sulfur in the samples was 15 wt.%, 35 wt.% and 57 wt.% respectively for pyrite, arsenopyrite and the flotation concentrate. Changes in sulfide sulfur concentration and the formation of oxide phases during fungal treatment were confirmed using Raman spectroscopy and X-ray diffraction analysis. These results suggest that P. chrysosporium is a potential microorganism for oxidative decomposition of metal sulfides associated with refractory gold ores.     

某微细粒含砷含碳难处理金矿浮选试验研究

针对某微细粒含砷含碳难处理金矿进行了浮选试验,在磨矿细度-0.074mm含量为90%条件下,采用浮选条件试验确定的最佳药剂制度,通过两次粗选、三次精选、三次扫选的闭路浮选流程可以获得精矿金品位41.90%、金回收率80.64%的浮选指标。工艺矿物学研究结果表明,尾矿中的金主要以微细粒贫连生体硫化物、硫化物又包裹金的形式存在,采用浮选工艺难以有效回收。     

某铜矿石可选性试验

某铜矿石铜矿物主要为黄铜矿,脉石矿物中主要是斜长石,分选过程中要求同时得到铜精矿和硫精矿。根据矿石性质,通过浮选条件试验和流程试验,结果如下:采用混合浮选—分离浮选流程,当磨矿细度为75%-0.076mm左右时,可获得的铜精矿含铜25.31%、含金6.7g/t,铜、金回收率分别为87.50%、84.52%。试验中未获得合格的硫精矿;采用一粗一扫二精选别流程,可获得单一的铜精矿。其铜品位与回收率分别为19.13%与88.13%,铜精矿含金5.33g/t,金的回收率为89.55%。方案Ⅰ铜精矿指标较好,方案Ⅱ流程简单、生产成本低。     

Enhanced hydrochloric acid leaching of nickel

Dissolution rates of nickel in hydrochloric acid with and without the presence of thiourea have been studied by means of rotating disc methods with solution analysis. In the absence of thiourea an apparent activation energy value of 61.1 ± 12.1 kJ. mol⁻¹ was determined. Such a high value is inconsistent with a diffusion controlled process and this was supported by the lack of dependency of the dissolution rate on rotational speed. A reaction controlled process is indicated. In 8.4 mol. dm⁻³ hydrochloric acid the thiourea concentration range producing optimum dissolution rates was 10⁻³ to 10⁻² mol. dm⁻³. At 70° C the rate of leaching was enhanced by some 105 %. Tests using radiochemical labelling of the sulphur and of the carbon separately in the thiourea molecule confirmed previous proposals, for cobalt dissolution, that hydrogen sulphide is produced as a by-product of the cathodic depolarisation reaction involving the thiourea and is adsorbed on the metal surface in the molecular state, forming activated anodic sites which enhance anodic dissolution. At the 10⁻¹ mol. dm⁻³ thiourea concentration level stimulation of the nickel dissolution process gave way to its partial inhibition with a maximum diminution at 30°C of 50 %.     

Bitumen-air aggregates flow to froth layer: II. Effect of ore grade and operating conditions on aggregate composition and bitumen recovery

Size, rise velocity, shape, and composition of bitumen-air aggregates floating to the froth layer during the processing of 11.1% bitumen Estuarine ore, and 7.2% bitumen Marine ore under various operating conditions (caustic dosage and feed density) were determined. The flux of the bitumen-air aggregates inside a Primary Separation Vessel (PSV) processing 2 tonnes/hour of the ore was in-situ monitored and video recorded. The mass of bitumen contained in the aggregates floating to the froth layer under different operating conditions was calculated on the basis of the measured rise velocities and dimensions of the aggregates. It was found that the type of ore processed was the parameter having the largest effect on size and composition of the bitumen-air aggregates floating to the froth layer inside the PSV during a 50°C warm slurry extraction process. In the case of the Estuarine ore the average mass of bitumen contained in an average aggregate was ca. 9^*10⁻⁴ g, and the average aggregate size was ca. 1.0 mm. During processing of the low grade (Marine) ore the aggregates were smaller (within 0.33–0.69 mm) and they carried much less (from 0.17–1.37^*10⁻⁴ g) bitumen, depending on other operating conditions (caustic dosage and feed density). A good correlation between size of the bitumen-air aggregates and bitumen recovery in the primary separation vessel was found. Thus, size of the aggregates can be used as an indication of better flotation recovery.     

Comparison of gold adsorption by Chlorella vulgaris,rice husk and activated carbon

Chlorella vulgaris and rice husk were selected from microorganisms and agricultural waste, respectively, to create new gold-eluteable adsorbents for adsorption of gold–thiourea complex, and compared with activated carbon. The maximum gold adsorption of heated-immobilised C. vulgaris, heated rice husk, and activated carbon was 10.34, 28.22 and 35.88 mg Au/g adsorbent, respectively. FTIR spectrum, thermodynamic study and elution tests indicated that heated-immobilised C. vulgaris and heated rice husk adsorbed gold by chemical adsorption: co-ordinate covalent bond. The active functional groups of heated-immobilised C. vulgaris were ketone, carboxylate and ester, while the groups of heated rice husk were ketone, carboxylate and siloxane. Activated carbon mainly adsorbed gold by physical adsorption. Gold adsorbed onto heated-immobilised C. vulgaris, heated rice husk, and activated carbon was able to be eluted by 0.5 M Na₂S₂O₃ to 100, 87 and 41%, respectively. Although heated-immobilised C. vulgaris had the highest eluteability, it adsorbed less gold. Therefore, heated rice husk could be used as an alternative adsorbent for gold–thiourea pre-concentration.     

Ultrasonic elution of gold from activated carbon

The feasibility of using ultrasound to enhance the elution of gold from activated carbon was investigated. A laboratory-scale elution column immersed in an ultrasonic bath was used to investigate three eluant systems. The kinetic activity of the activated carbon was improved in the elution with sonication. Ultrasonic radiation improved the recoveries and kinetics of elution considerably. This could possibly be attributed to an increase in diffusive transport caused by acoustic vortex microstreaming and microjets, as well as the prevention of activated carbon fouling which can lead to the blockage of active sites. The rate of elution was significantly increased by the addition of ethanol to the aqueous eluant, especially in the presence of ultrasound. It could be attributed to the increased activity of smaller ions in preference to gold cyanide in the presence of ethanol. Ethanol, by capturing the primary radicals (H^* and OH^*), generated secondary radicals (C₂H₄OH*) which could be responsible for the increased efficiency. The introduction of ultrasound into the conventional elution systems made it possible to elute gold cyanide from activated carbon under less severe conditions.     

On gold extraction from rebellious ores

The paper generalizes research findings on application of chemical additives to stage-by-stage processing of rebellious gold-bearing ores. The designed stages of gold extraction intensification are the controlled mineral alteration by preparation, use of conventional and specific collecting agents to prepare mineral surface to sorption to intensify flotation, creation of selective collecting agents, and cyanation optimization by introducing additional oxidation agents. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 2, pp. 102–109, March–April, 2009.     

Estimation of gold inventory in large carbon in leach tanks

The preparation of the month end gold production report is required by the mine owners to regularly assess the performance of the plant against budgeted values. However the preparation of a gold production report is often complicated by the large inventory of gold in the carbon in pulp (CIP) or carbon in leach (CIL) tanks used to adsorb leached gold from the solution. Indeed a 600 m³ CIP/CIL loaded with 15 g/L of activated coal charged with 8000 g of gold/ton of coal may retain up to 72 000 g (2200 troy oz) of gold. The estimation of the inventory implies the determination of the concentration of carbon in a tank and of the gold content of the species contained in the tanks. This paper assesses the errors associated with the sampling of CIL tanks to measure these concentrations and describes the impact of these errors on the estimation of the gold inventory in the CIL tanks of the Agnico-Eagle Mines Limited Lapa concentrator.     

难选氧化铜矿分选技术现状与展望

本文介绍了我国铜矿资源的分布、金属铜的生产、消费现状及主要生产企业和难选铜矿石的分选技术现状。着重介绍了硫化浮选法、有机酸浮选法、氨浸硫化沉淀浮选法、离析-浮选法、硫化焙烧-浮选法、化学选矿-浮选联合法、细菌浸出法、氯化焙烧-化学选矿法和特殊捕收剂法的原理和研究现状,对今后氧化铜矿石选矿的发展方向进行了展望。     

国内外硫化铜镍矿选矿现状及未来发展方向

从矿石特性、选矿工艺、选矿药剂等方面对目前硫化铜镍矿选矿工艺技术现状进行归纳总结,分析了当前硫化铜镍矿选矿工艺存在的问题,就如何进一步提高硫化铜镍矿综合利用率、有针对性的回收伴生元素,实现集约化选矿等方面进行了阐述,初步提出硫化铜镍矿选矿技术未来发展的方向和研究内容,为从事硫化铜镍矿选矿的科技工作者和现场技术管理人员提供参考。     

PVC废塑料与石煤混合焙烧-酸浸提钒试验

石煤提钒过程中,为提高钒浸出率,往往会在焙烧阶段添加添加剂,而PVC废塑料则是没有得到很好回收利用的大宗废弃物。针对这一状况,以PVC废塑料为添加剂,进行了石煤提钒工艺条件研究。结果表明：①在焙烧过程中加入与石煤质量比为10%的PVC废塑料,在升温速率为10 ℃/min,焙烧温度为800 ℃,焙烧时间为60 min,焙砂酸浸的硫酸体积浓度为15%,液固比为1.5 mL/g,浸出温度为95 ℃,浸出时间为4 h情况下,钒浸出率可达92.60%,与空白焙烧-酸浸工艺相比,钒浸出率提高了6.50个百分点。②石煤焙烧阶段加入10%的PVC废塑料后,石煤中各主要元素的浸出率有不同程度的提高,说明PVC的加入有助于破坏石煤的矿物结构,促进后续酸浸过程中钒的浸出,但并不给后续富集钒和沉钒工艺带来不利影响。因此,在石煤提钒焙烧过程中添加PVC废塑料,可改善钒的浸出效果,降低钒的浸出成本,实现PVC废塑料的综合利用,经济效益和环境效益显著。     

某复杂铜硫矿浮选分离与综合回收试验研究

某复杂铜硫矿原矿硫铁含量高,现场为高碱工艺流程,铜硫分离困难且金银综合回收效率低。采用硫化钠预先活化,"石灰+羧化壳聚糖"作黄铁矿和磁黄铁矿抑制剂,粗选pH=8.5,经一粗两精三扫优先浮选流程可得到含铜24.63%、含金3.41 g/t、含银952.05 g/t,铜回收率84.45%、金回收率32.58%、银回收率75.70%的铜精矿。羧化壳聚糖为清洁高效有机高分子化合物,能高效选择性抑制硫铁矿,在提高主金属铜回收率的同时,伴生金银矿物得到了高效综合回收。     

Enhanced leachability of gold and silver in cyanide media: Effect of alkaline pre-treatment of jarosite minerals

Composite samples of tailings containing gold (1.35 g/t) and significant amounts of silver (155 g/t) were subjected to batchwise cyanide leaching to assess the feasibility of extracting gold and silver. The tailings are waste solids arising from flotation and leaching operations whereby the flotation product (sphalerite concentrate) is calcined and then solubilised into dilute sulphuric acid solution and eventually sequestered from the electrolyte by electrowinning. Silver and gold are part of the zinc refinery residue, flotation tailings and to a limited extent the calcine leach tailings. Mineralogical results showed that composite tailings are refractory in nature (44% quartz, 17% silico aluminates and 12% jarosites).The concept of enhancing gold and silver recovery from the tailings focused on firstly decomposing the jarosite minerals by alkaline pre-treatment and then secondly leaching with cyanide solution. These two steps ensured that free gold and silver found in the zinc refinery residue and in the jarosite minerals could be leached simultaneously. The composite tailings were treated with Ca(OH)₂ solutions and then heated to 90 °C for 2 h to decompose the silver-bearing mineral (Ag,PbFe₃(SO₄)₂(OH)₆). The alkaline pre-treated tailings were then subjected to cyanide leach tests at different NaCN dosages (2.5–10 kg/t) and particle size (96–200 μm). Without an alkaline pre-treatment stage, leach efficiencies achieved were 41% and 25% for gold and silver, respectively at 40 °C and 8 h mixing time. But, better leach efficiencies (55% for Au, 81% for Ag) were achieved after the feed was pre-treated with Ca(OH)₂. The leaching mechanism of gold was explained by the shrinking sphere model denoted by surface chemical reaction.     

The effect of heat treatment on the magnetic properties of pyrite

The effect of thermal treatment on the magnetic properties of pyrite was investigated. Untreated pyrite showed evidence of both paramagnetic and ferromagnetic components. After heat treatment, the saturation magnetisation increased considerably until 800 °C when the magnetisation decreased, and then increased again after 900 °C. These changes are due to phase changes induced by oxidation. The wet magnetic recovery of the untreated sample was 25%, which increased to over 90% after treatment at 500 °C. The recovery of the magnetic fraction plateaus after treatment at higher temperatures, implying that a sample magnetisation greater than 5 kA m⁻¹ leads to a recovery greater than 90% for this size fraction.     

The development of an environmentally friendly leaching process of a high C,As and Sb bearing sulfide gold concentrate

An environmentally friendly leaching process, consisting of the pretreatment of alkaline pressure oxidation and thiosulfate leaching, has been developed to efficiently extract gold from a high carbon, arsenic and antimony bearing sulfide gold concentrate. The Au extraction from the concentrate by direct cyanidation was very low mainly due to the encapsulation of gold by associated minerals and the preg-robbing effect of graphite and organic carbon. The pretreatments of permanganate oxidation and oxidative roasting both could effectively liberate encapsulated gold and eliminate the preg-robbing effect on cyanidation. However, the reagent dosage of permanganate oxidation was high and the final oxidation solution contained substantial quantities of toxic ions. The flue gas of oxidative roasting also contained a lot of poisonous oxides, and the extremely drastic reaction environment of roasting led to the secondary encapsulation of gold by newly generated oxides. The pretreatment of alkaline pressure oxidation effectively liberated encapsulated gold with less than stoichiometric reagent dosage and simultaneously relieved the secondary encapsulation of gold, but could not completely remove graphite and organic carbon. Because carbonaceous matter had a weak affinity for gold thiosulfate complex, the Au extraction by thiosulfate leaching after the pressure oxidation achieved 86.1% whilst the thiosulfate consumption was 35.3 kg/t-concentrate. This process of alkaline pressure oxidation–thiosulfate leaching neither used toxic reagent nor released poisonous gas, and furthermore its effluents contained few toxic ions.     

浅谈活性炭吸附-原子吸收法测金在塔吉克斯坦库马尔克金矿的应用

本文采用活性炭吸附-原子吸收法对塔吉克斯坦库马尔克金矿含金样品进行测定,首先通过王水分离、活性炭富集金,再将得到的金提取定容,最后使用火焰原子吸收仪测定金的含量,该方法测金简单便捷,重复性和再现性好,作者围绕该方法在实际中的运用展开具体的阐述。