方铅矿氧化过程中温度和氧化物浓度的影响研究

通过采用硫酸铁作氧化剂,在pH=2、温度50 ℃和25 ℃时对不同浓度氧化介质中方铅矿进行氧化试验。通过试验计算出反应速率常数与反应级数、反应活化能并确定反应动力学方程。分析温度和氧化介质浓度对方铅矿氧化速率的影响,在50 ℃条件下,用Fe₂(SO₄)₃作为氧化剂时,溶液的浓度为100 mg/L时反应进行很快。当溶液的浓度越高时,溶液中硫酸根离子的浓度就越高,越容易生成PbSO₄沉淀,阻碍反应的进行。而在25 ℃时,反应非常缓慢甚至不进行。     

细菌和硫酸铁氧化方铅矿的动力学和机理

《Hydrometallurgy》2004年第75卷第（1～4）期上发表了Silva G．D．介绍有关细菌和硫酸铁氧化方铅矿的动力学和机理的文章。     

硅氟酸溶液中方铅矿的阳极氧化动力学研究

用动电位扫描法测量不同条件下硅氟酸溶液中石墨电极上方铅矿的阳极氧化曲线 ,研究方铅矿的阳极氧化动力学。结果表明 ,方铅矿的阳极氧化曲线明显地分为 3段 ,氧化区di/dφ >0 ,传质区di/dφ=0 ,另一氧化过程 ,di/dφ >0。交换电流密度i0 随着温度的增加而增大 ,电化学传递系数 β的平均值为 0 16。搅拌速率、矿浆液固比对换电流密度i0 有较大的影响     

方铅矿的两矿法浸出动力学研究

对方铅矿精矿和软锰矿两矿共同浸出动力学过程进行了研究。结果表明, 在常压下40 g/L稀硝酸溶液中, 采用空气搅拌, 两矿法浸出过程为内扩散控制, 浸出产物硫膜的脱除、方铅矿粒度、浸出剂浓度以及添加剂均对铅浸出率有重要的影响。     

矿浆温度对方铅矿浮选效果的影响及机理研究

以丁基黄药（NaBX）为捕收剂,甲基异丁基甲醇（MIBC）为起泡剂,通过单矿物浮选试验,研究了矿浆温度变化对方铅矿浮选效果的影响,同时通过红外光谱（FTIR）、Zeta电位、捕收剂吸附量、X射线光电子能谱（XPS）、矿浆黏度等测试分析并结合浮选动力学研究,探究了矿浆温度变化对方铅矿浮选效果的影响机理。结果表明:矿浆温度变化会显著影响方铅矿浮选效果,低温（5℃）下的回收率较常温（20℃）下的降低约7个百分点;NaBX在方铅矿表面的吸附产物为丁基黄原酸铅,矿浆温度变化不改变其在方铅矿表面的化学吸附特性,但矿浆温度降低会减弱方铅矿表面的氧化程度,减少表面活性吸附点,使NaBX在方铅矿表面的吸附量减小从而降低浮选效果;低温下矿浆黏度增大,使气泡上升速度及气泡与矿粒碰撞速率降低,这在一定程度上会降低浮选效果;浮选动力学表明:低温（5℃）下的最大回收率和浮选速率常数小于常温（20℃）下的。      

MoSi2低温氧化动力学研究

通过热重量分析法测定了MoSi2在低温氧化不同时间后的重量变化,并根据曲线拟合分析了MoSi2的低温氧化过程。结果表明,在500℃时MoSi2材料的氧化过程受扩散和反应双重影响,氧化速率呈阶段式变化：先主要受扩散控制,氧化增重与时间呈指数关系;随后反应成为主要控制因素,氧化增重与时间呈线性关系;如此反复,表现出比400℃和600℃时快得多的氧化速率。在400℃、600℃时MoSi2的氧化速率主要取决于氧化反应,且与反应进行的时间呈线性关系,氧化144h后因钝化质量维持不变。图3,表1,参7。     

古尔胶对闪锌矿和方铅矿浮选的影响

根据吸附量测定、电动电位测量和浮 选试验研究了古尔胶与闪锌矿和方铅矿的相互作用。古尔胶在矿物表面上的最大吸附量发生在：闪锌矿ＰＨ＝７．５和方铅矿ＰＨ＝１１．５。古尔胶在方铅矿上的吸附密度比在闪锌矿上的高。古尔胶在这两种矿物上的吸附等温线具有朗格缪尔特笥。随古尔胶浓度升高,和和闪锌矿的电泳迁移率变负,而等电点未偏移。有古尔胶存在情况下,在ＰＨ１２时,方铅矿的回收率降低２０％,在ＰＨ＝８－１２,闪锌矿     

铁闪锌矿氧化动力学研究

本文采用热天平和二氧化硫吸收液电导连续测定方法,研究了温度和氧浓度对铁闪锌矿氧化的影响,计算了氧化反应速度和反应活化能,探讨了反应机理。     

温度对极低浓度瓦斯氧化影响的研究

 摘要：本文实验通过配置浓度为0.75%、0.5%和0.25%的极低浓度甲烷来模拟矿井乏风,使三个浓度的甲烷通过高温炉膛,收集炉膛排除的气体,并对收集气体进行测试,以得到矿井乏风高温氧化的条件和规律。实验通过调整炉膛温度以得到不同温度下极低浓度甲烷的氧化情况。结果表明,甲烷浓度越高则氧化所需的温度越低;甲烷浓度越低,氧化所需的温度越高;根据实验研究得出极低浓度甲烷在锅炉炉膛中应该在750℃左右时即开始被氧化,甲烷浓度逐渐降低,且在800℃左右时能被被完全氧化。     

Effect of galena grain size on flotation kinetics

Laboratory tests of relationship between kinetics of flotation of pure galena smaller than 38 μm in size and concentration of potassium butyl xanthate show that flotation rate undergoes considerable reduction when mineral grains are under 18 μm in size. Size grades below 18 μm show the slowest flotation rates that are nearly equal at the collector concentration of 0.5 mg/l. With the higher collector concentration, the flotation rate grows in all size grades under testing.     

Diagnostic leaching of galena and its oxidation products with EDTA

Many authors have used EDTA as a means of determining the extent of oxidation of flotation pulps. However, there have been few documented studies of the reaction mechanisms in the interaction of EDTA with sulphide minerals and their oxidation products. This paper examines the use of EDTA to extract lead oxidation products from galena. In the first instance, it will be demonstrated that all oxygen containing galena oxidation products (i.e. sulphate, hydroxide, oxide, and carbonate, but not polysulphide or sulphur) are rapidly solubilized in EDTA. Secondly, it is shown that EDTA does not extract lead from un-reacted galena. Continued extraction of lead with increasing conditioning time is due to continued galena oxidation, not to the extraction of lead from galena. Argon gas purging minimises this oxidation whereas the use of air or nitrogen gas purging do not. Using information gathered from these experiments, an improved EDTA extraction technique was developed and compared with other techniques used within the mining industry.     

有机抑制剂鞣酸对黄铜矿和方铅矿浮选的影响

通过单矿物、人工混合矿、实际矿石浮选试验,吸附量和红外光谱测试,研究了鞣酸对黄铜矿和方铅矿浮选的影响及其与矿物的作用机理。结果表明,鞣酸对方铅矿具有强抑制作用,对黄铜矿浮选的抑制作用较小。当鞣酸用量为5 mg/L,浮选180 s时,黄铜矿回收率为83.30%,而方铅矿的回收率只有17.65%。吸附量测试表明,鞣酸在黄铜矿表面的吸附密度为2.03 mg/m2,在方铅矿表面能够达到6.05 mg/m2。红外光谱检测表明,鞣酸通过酚羟基与方铅矿表面发生作用,与黄铜矿作用则很弱,这正是鞣酸能抑制方铅矿的原因。     

Electrochemical passivation of sphalerite during bacterial oxidation in the presence of galena

Sphalerite (ZnS), a mineral of particular hydrometallurgical interest, is generally found associated with galena (PbS). As such, the effect of galena on the leaching of sphalerite is of importance, and has been studied here for bacterial and ferric sulphate leaching. During both leaching processes galena was selectively oxidised to anglesite in favour of the dissolution of sphalerite. It is believed that this selective behaviour is due to galvanic interactions between the two minerals, whereby galena is sacrificed and sphalerite is passivated. This theory is consistent with the order of measured rest potential values of both minerals in solution, being 325 mV for galena and 375 mV for sphalerite (versus a standard hydrogen electrode). During bacterial oxidation, sphalerite passivation was observed across a range of mixed sphalerite/galena samples, including a mineral species and four ore specimens of varying grades. From the bacterial oxidation of a mixed mineral species, sphalerite was found to leach in the presence of lead sulphate precipitate, though the presence of this precipitate is believed to have caused diffusion limitation.     

煤低温氧化过程中自由基浓度与气体产物之间的关系

利用煤低温氧化装置和顺磁共振实验,研究了褐煤、气煤、气肥煤和无烟煤在不同氧化温度下气体及自由基的变化规律,宏观和微观相结合来揭示煤自热低温氧化规律。研究结果表明：煤低温氧化过程中,煤被氧化分子侧链断裂,产生气体与自由基,生成的CO,C 2H 4标志性气体生成量随温度增加而增加,相应地自由基浓度也随氧化温度的增加而增加。煤被氧化生成CO,C 2H 4标志气体量与自由基浓度呈阶段性规律：低温氧化蓄热阶段,CO气体生成量小或未出现CO气体,此时自由基浓度变化小;从开始出现CO至出现C 2H 4气体的氧化自热阶段,CO生成量随氧化温度缓慢增加,而自由基浓度也逐步增加;从出现C 2H 4至出现H 2气体的深度氧化阶段,CO和C 2H 4生成量随氧化温度增加而快速增加,自由基浓度随氧化温度增加而增幅变小。     

Cyanide oxidation by ozone in cyanidation tailings: Reaction kinetics

The treatment of cyanidation effluents is one of the main problems the gold mining industry faces. Different methods are available for the removal of cyanide but in most cases the consumption of reagents raises the cost to unaffordable levels, or there exists the formation of residual byproducts that are also toxic. Ozone gas is used in a new alternative approach that presents several advantages for oxidation of cyanide compounds. However, the lack of information on the reactions of cyanide compounds with ozone has limited its industrial application in cyanidation effluents.The oxidation of cyanide by ozone in aqueous solutions was studied using a bubble column reactor. The reactor was operated at different conditions of pH, ozone dosage rate, gas flow rate and cyanide concentration. Preliminary experiments were performed with synthetic cyanide solutions and the results :showed that the rate of cyanide oxidation may be described by an equation which is first order with respect to ozone concentration in the oxidizing gas, and zero order with respect to cyanide concentration in the aqueous solution. The rate constant obtained for the reaction was about 10⁻⁵ mol/L·s. The stoichiometry estimated for the reaction indicated one mole of cyanide reacts with one mole of ozone to form one mole of cyanate. These results were corroborated with industrial eff luents from two mines in Mexico.     

Effect of calcium hypochlorite on the flotation separation of galena and jamesonite in high-alkali systems

Jamesonite and galena have similar flotation properties, leading to difficulties in effectively separating these two minerals by means of conventional flotation. This study assessed the depressing effect of calcium hypochlorite [Ca(ClO)₂] on the flotation separation of galena and jamesonite in high-alkali systems. Flotation test results show that galena and jamesonite have substantially different floatability in high-alkali systems. The addition of Ca(ClO)₂ depresses the flotation of jamesonite, but the depressant is unselective against galena. A flotation separation test of a mixture of galena and jamesonite was conducted. The results show that the recovery of galena and jamesonite is 92.26% and 89.75%, respectively. Adsorption measurements and infrared spectral analysis indicate that when diethyldithiocarbamate (DDTC, collector) interacts with galena and jamesonite, chemical adsorption occurs on the mineral surfaces, producing hydrophobic lead diethyldithiocarbamate (PbD₂). In a high-alkali solution, Ca(ClO)₂ exhibits little interference regarding the adsorption of DDTC on the galena surface, while it significantly inhibits the adsorption of DDTC on jamesonite. The flotation behavior of jamesonite is depressed by Ca(ClO)₂ mainly because the latter enhances the surface hydrophilicity of the former. These results provide a reference for separating galena and jamesonite concentrates prior to smelting.     

Electrochemistry of galena oxidation as the basis for optimization of agent modes in flotation of polymetallic ores

The authors studied electrochemical oxidation of a galena electrode in aqueous alkaline solutions and established the limiting stage of galena oxidation and its kinetic characteristics. IR-spectroscopy analysis of oxidation products showed that complex chemical compounds were formed on the surface of the galena electrode under controllable oxidation.     

磷酸酯淀粉在黄铜矿及方铅矿表面吸附研究

通过单矿物浮选试验、吸附量试验、X射线光电子能谱和原子力显微镜(AFM)研究了磷酸酯淀粉对黄铜矿及方铅矿浮选的影响及吸附机理。单矿物浮选试验表明,磷酸酯淀粉对方铅矿的抑制能力强,对黄铜矿抑制能力弱。吸附量试验表明,磷酸酯淀粉在方铅矿表面的吸附密度大于在黄铜矿表面的吸附密度。XPS检测到黄铜矿表面的铁与硫原子以及方铅矿表面铅和硫原子价态发生了变化。方铅矿和黄铜矿不同的表面性质是造成磷酸酯淀粉在两种矿物表面吸附差异的重要原因。     

Effect of cuprous cyanide,dry and wet milling on the selective flotation of galena and sphalerite

Batch flotation tests of a lead–zinc sulphide composite ore from the Rosh Pinah Mine have been carried out at pH 8.5 in the presence of copper cyanide complexes. These copper cyanide complexes are often found in the recycled water that is used in the milling and the lead flotation circuits. Flotation results have shown that cuprous cyanide complexes can activate sphalerite. In addition, the activation and subsequent flotation of sphalerite was greater when the composite was dry milled as compared to wet milling. Surface analysis of copper(I)-activated sphalerite samples was studied by X-ray photoelectron spectroscopy (XPS). XPS results showed the presence of copper species on the surface of sphalerite after activation with cuprous cyanide complexes. The copper species could be removed from the surface of sphalerite after treatment with sodium cyanide. This explains, amongst others reasons, the high cyanide requirement at Rosh Pinah Mine for the efficient depression of sphalerite in the lead flotation circuit.