Accelerating the decarbonization of carbonaceous gold ore by suspension oxidation roasting towards the improvement of gold leaching efficiency

Eliminating the gold preg-robbing effect of carbonaceous matter in carbonaceous gold ores is crucial for gold leaching. In this study, suspension oxidation roasting was proposed to accelerate the decarbonization of carbonaceous gold ore. The characteristics of oxidation reaction process and gas release were analyzed by TG-DTA-FTIR. The phase transformation and microstructure evolution of samples during roasting were analyzed by XRD, SEM and BET. The results show that the gold preg-robbing effect was eliminated after the gasification of carbonaceous matter, and the CaO generated by decomposition of carbonates can effectively capture the SO₂. After roasting for 75 min at 650 °C in a 20% O₂ atmosphere, the total carbon removal rate reached 99.42%, the distribution of exposed gold increased from 28.85% to 77.10% and the gold leaching efficiency increased from 4.55% to 84.83%. In addition, about 70% sulfur was mainly fixed in the roasted products in the form of sulfate. Therefore, the suspension oxidation roasting process is an efficient and clean pretreatment method for carbonaceous gold ores.     

Behavior of phase transformation of Baotou mixed rare earth concentrate during oxidation roasting

Based on the new process named “Combination Method” for metallurgy and separation of Baotou mixed rare earth concentrate (BMREC), the aim of this paper is to clearly elucidate the phase change behavior of BMREC without additives during oxidative roasting at 450–800 °C. The results indicate that the bastnaesite in BMREC is decomposed at 450–550 °C, the weight loss is about 10.3 wt%, and the activation energy (E) is 144 kJ/mol. The bastnaesite in BMREC is decomposed into rare earth fluoride, rare earth oxides (La₂O₃, Ce₇O₁₂, Pr₆O₁₁ and Nd₂O₃), and CO₂, particularly, with the increase of roasting temperature, bastnaesite in BMREC is more completely decomposed into LaF₃, which causes a decrease in leaching rate of La during the HCl leaching process. Additionally, the maximum cerium oxidation efficiency reaches about 60 wt% when the roasting temperature is equal to or above 500 °C, and the oxidation reaction rate of cerium increases with the increasing roasting temperature.     

焙烧方式对含砷金精矿中金、银浸出率的影响

某含砷金精矿中金矿物嵌布粒度较细,金主要以硫化物(黄铁矿、毒砂)包裹金形式存在。采用焙烧预处理-氰化浸出工艺,研究了一段焙烧、两段焙烧和添加剂焙烧对氰化浸出的影响。结果表明,采用常规一段、两段焙烧方式,金浸出率均未达到90%,银浸出率低于50%; 添加剂焙烧效果显著,在焙烧温度650 ℃、时间1.0 h、添加剂用量NaXY 100 kg/t+YC-1 20 kg/t的条件下,金浸出率达到93.56%,银浸出率达62.45%。     

Solution-Processed Organic Solar Cells with High Open-Circuit Voltage of 1.3 V and Low Non-Radiative Voltage Loss of 0.16 V

Compared with inorganic or perovskite solar cells, the relatively large non-radiative recombination voltage losses (ΔV_non-rad) in organic solar cells (OSCs) limit the improvement of the open-circuit voltage (V_oc). Herein, OSCs are fabricated by adopting two pairs of D–π–A polymers (PBT1-C/PBT1-C-2Cl and PBDB-T/PBDB-T-2Cl) as electron donors and a wide-bandgap molecule BTA3 as the electron acceptor. In these blends, a charge-transfer state energy (E_CT) as high as 1.70–1.76 eV is achieved, leading to small energetic differences between the singlet excited states and charge-transfer states (ΔE_CT ≈ 0.1 eV). In addition, after introducing chlorine atoms into the π-bridge or the side chain of benzodithiophene (BDT) unit, electroluminescence external quantum efficiencies as high as 1.9 × 10⁻³ and 1.0 × 10⁻³ are realized in OSCs based on PBTI-C-2Cl and PBDB-T-2Cl, respectively. Their corresponding ΔV_non-rad are 0.16 and 0.17 V, which are lower than those of OSCs based on the analog polymers without a chlorine atom (0.21 and 0.24 V for PBT1-C and PBDB-T, respectively), resulting in high V_oc of 1.3 V. The ΔV_non-rad of 0.16 V and V_oc of 1.3 V achieved in PBT1-C-2Cl:BTA3 OSCs are thought to represent the best values for solution-processed OSCs reported in the literature so far.     

烘烤条件对奇亚籽油理化性质及脂肪酸组成的影响

对奇亚籽进行烘烤、压榨取油,测定不同烘烤条件(温度、时间)下奇亚籽油的理化性质及脂肪酸组成,探讨烘烤温度和时间的影响。结果表明:随着烘烤温度的升高和烘烤时间的延长,奇亚籽油色泽加深,酸价、过氧化值、K_(232)、K_(268)均呈现上升趋势,且180℃烘烤50 min以上较其他条件下显著升高(p0.05);烘烤条件对脂肪酸组成无影响。故烘烤奇亚籽不宜在高温下进行,若采用180℃烘烤时,则时间不应超过50 min。     

粗金粉中金的氯浸-控制电位还原精炼

某冶炼厂氰化金泥还原得到的粗金产品纯度较低，采用氯浸-还原工艺对粗金进行了精炼提纯。在生产工艺中采用盐酸+氯酸钠对粗金进行氯浸溶解，用焦亚硫酸钠控制电位选择性还原浸出液中的金。采用补水-冷却使银和铅从氯浸液充分沉淀析出，通过调整pH值、改变焦亚硫酸钠添加方式、精确控制还原电位等方法，产品金锭达到IC-Au99.99标准。两年的生产实践创造了明显的经济效益。     

钙化-酸浸提钒沉钒母液中锰的回收

对钙化?酸浸提钒沉钒母液中锰资源的回收，一方面可以提升提钒工艺的经济效益，另一方面可避免母液循环时锰浓度不断累积而影响氧化钒产品质量，从而有助于实现母液闭路循环而提升全流程的环境效益。本工作提出了采用草酸沉淀法高效回收沉钒母液中的Mn2+，考察溶液体系pH值、草酸加量系数、反应温度和时间对锰回收率及沉淀产物物相组成的影响，以及草酸沉淀分离锰后母液的循环次数对钒浸出过程的影响。结果表明，草酸沉淀法可高效分离沉钒母液中的Mn2+，在溶液体系pH=4.0、草酸加量系数为1.5、反应温度为50℃、反应时间为60 min的条件下，锰回收率达94.33%，所得产物为纯度大于98%的水合草酸锰，为片状晶体，并呈花簇状生长。将脱锰后的沉钒母液循环至酸浸段，对钒浸出率及浸出液中锰的浓度没有明显影响，表明该方法有助于实现钙化?酸浸提钒中废水的闭路循环。     

白云鄂博矿焙烧浸出-萃取沉淀分离稀土及钍的试验研究

采用焙烧浸出-萃取沉淀法从白云鄂博稀土精矿中分离稀土和钍,得到最佳焙烧浸出条件为: 矿酸比1∶1.5、焙烧时间1 h、焙烧温度200 ℃、水浸液固比8∶1、水浸时间4 h、水浸温度50 ℃,最佳条件下CeO₂、La₂O₃、Nd₂O₃、Pr₆O₁₁、Sm₂O₃和ThO₂浸出率分别为80.77%、69.24%、95.71%、76.82%、93.31% 和98.13%。采用羧酸类萃取-沉淀剂从浸液中萃取分离稀土和钍,在萃取-沉淀剂皂化度70%、料液pH=3.1、萃取-沉淀剂和钍的摩尔比4∶1的最佳条件下,稀土和钍萃取-沉淀率分别为19%和90%,实现了稀土和钍的有效分离。     

Simultaneous extraction of gold and zinc from refractory carbonaceous gold ore by chlorination roasting process

A novel process based on chlorination roasting was proposed to simultaneously recover gold and zinc from refractory carbonaceous gold ore by using NaCl as chlorination agent. The effects of roasting temperature, roasting time and NaCl content on the volatilization rates of gold and zinc were investigated. The reaction mechanism and the phase transition process were also analyzed by means of SEM, EDS and XRD. The results demonstrated that under the optimal conditions of NaCl content of 10%, roasting temperature of 800 °C, roasting time of 4 h and gas flow rate of 1 L/min, the rates of gold and zinc were 92% and 92.56%, respectively. During low-temperature chlorination roasting stage, a certain content of sulfur was beneficial to the chlorination reactions of gold and zinc; and during high-temperature chlorination roasting stage, the crystal structure of vanadium-bearing mica was destroyed, and the vanadium-containing oxides were beneficial to the chlorinating volatilization of gold and zinc. Eventually, the chlorinated volatiles of gold and zinc could be recovered by alkaline solution.     

某含铁铅锌尾矿中铁分离试验研究

以某含铁铅锌尾矿为研究对象,通过对铅锌尾矿磁化焙烧时碳粉用量、温度、时间以及磁场强度最佳条件的研究,提出从铅锌尾矿中分离铁元素的合理方案,探讨铅锌尾矿中铁元素二次利用的可能性。试验结果表明,磁化焙烧时最佳碳粉用量为20%、焙烧温度为750℃、焙烧时间为80 min、磁场强度为256 kA/m,在此条件下所得精矿的铁品位为58.44%,回收率为16.98%。