Extraction of silver from a refractory silver ore by sono-cyanidation

In this study, effect of ultrasound on silver extraction from a refractory silver ore containing both native silver and various silver sulphide minerals was investigated. Main effects and interaction effects of pulp density, ultrasonic frequency, cyanide concentration, air flow rate and agitation speed on the extraction rate of silver were studied by a two-level fractional factorial experimental design. A few additional cyanidation tests were also conducted to verify the findings of the designed experiments.It was found that the overall extraction yield was varied from 67% to 90% depending on the operating conditions used in the sono-cyanidation tests (48 h). However, it was varied from 63% to 80% by same operating conditions used in the direct cyanidation tests at the same cyanidation time. It was observed that an increase in the ultrasonic frequency has a negligible effect on the silver recovery. More importantly, it was determined that there were insignificant differences between the 24-h sono-cyanidation results and the 48-h direct cyanidation results for each cyanidation conditions. This finding, which is very important from the cyanidation practice standpoint, indicates that the cyanidation time can be reduced up to 50%, or the capacity of an operating silver extraction plant can be increased up to 100% by the sono-cyanidation by the refractory silver ores. In order to describe the rate of silver dissolution in the cyanide solutions, the experimental data were analysed using shrinking core models. It was found that there is a good fit between the experimental data and the models, indicating the rate of silver dissolution in cyanide can be described by a two-stage, porous layer diffusion controlled, shrinking core model.     

硫酸浸出矿液中砷的氢化物发生-原子荧光光谱法快速测定初探

采用氢氧化钾完全中和浸出矿液中的硫酸,在盐酸介质中加入硫脲、抗坏血酸还原。应用氢化物发生-原子荧光光谱法测定硫酸浸出矿液中微量砷的方法进行了探讨。其方法回收率在100%~102%之间,相对标准偏差在1.4%~2.2%之间,方法检出限为3.5×10-10g/mL,线性回归方程:IF=8.214×C+9.688,相关系数为0.9994。经实验证实,方法简便快速、准确可靠、可测范围宽,可直接测定液体样品。亦为硫酸浸出矿液的处理对环境保护的影响提供了科学依据。     

X射线荧光光谱法快速测定锰矿石中的主次组分

采用粉末压片法制样,使用ZSX Primus Ⅱ X射线荧光光谱仪实现了对锰矿样品中锰元素及杂质组分钠、镁、铝、硅、磷、钾、钙、铁的快速测试。虽然方法在分析准确度上不及化学法或熔融制样—X射线荧光光谱法,但方法的精密度好,测试范围广,分析结果与标准值和比对值基本吻合。方法简便、快速,可满足实验室对锰矿石批量检测的要求。     

汤家墩遗址冶炼遗物的科技研究

采用X射线荧光仪、X射线衍射分析仪、扫描电子显微镜及激光剥蚀电感耦合等离子体质谱等现代检测手段对汤家墩遗址的炉壁、炉渣及炉渣中的金属颗粒进行分析,进而探讨汤家墩古铜冶炼技术。结果表明：汤家墩遗址的炉壁为冶炼炉炉壁,炉渣为还原渣;根据铜颗粒中As,Ag,Sb,Bi等微量元素的含量,可以计算出汤家墩遗址炼渣中的铜颗粒来自于硫化铜矿的概率高达87.87%以上,从而表明汤家墩是采用“硫化铜—铜”的冶铜工艺进行冶炼的早期青铜文化遗址。这一研究结果不仅有利于枞阳地区青铜文化遗产的深入研究,而且对于探究枞庐地区青铜冶铸技术的发展与演变具有非常重要的意义。     

The automorphisms of Petit’s algebras

Let σ be an automorphism of a field K with fixed field F. We study the automorphisms of nonassociative unital algebras which are canonical generalizations of the associative quotient algebras K[t;σ]∕fK[t;σ] obtained when the twisted polynomial f∈K[t;σ] is invariant, and were first defined by Petit. We compute all their automorphisms if σ commutes with all automorphisms in Aut_F(K) and n≥m?1, where n is the order of σ and m the degree of f, and obtain partial results for n<m?1. In the case where K∕F is a finite Galois field extension, we obtain more detailed information on the structure of the automorphism groups of these nonassociative unital algebras over F. We also briefly investigate when two such algebras are isomorphic.     

ICP-AES法对铬铁矿中的多种元素进行定性与定量分析

采用ICP-AES法对铬铁矿首先进行定性分析,确定了铬铁矿中含有的元素种类;经过分析发现铬铁矿中含有Cr,Fe,Al,Mg,Zn,Co,Ni等29种元素。然后根据定性分析的结果,对铬铁矿中的主要元素Cr,Fe,Al,Mg,Ca,Ti,Si,Mn,V的含量进行测量。铬铁矿样品的前处理分两步进行,首先用碳酸钠-四硼酸钠在950 ℃下熔融30 min,然后用稀盐酸在80 ℃下浸取10 min,即可将样品完全溶解。实验结果表明,该方法的相对标准偏差为0.48%～2.05%,加标回收率为90.5%～111.3%,分析精确度满足要求。     

An Iterative Construction Heuristic for the Ore Selection Problem

The ore selection problem involves choosing a processing option for a number of mining blocks that maximises the expected payoff for a given level of financial risk. An innovative neighbourhood search heuristic is proposed for the ore selection problem. This iterative construction heuristic employs a stochastic demolition and reconstruction strategy. Computational experiments with this heuristic for two ore selection problem instances, one involving 2,500 blocks and the other involving 78,000 blocks, are given. These problem instances are made publicly available for use by future workers. Our computational experiments indicate that the proposed heuristic produces better quality solutions faster than a relay hybrid (constructive-simulated annealing) heuristic.     

Analytical solutions for ore fluid transport in fractured rocks: a case study on ore-forming processes of the stratabound skarn copper deposits in China

The Dongguashan skarn copper deposit can be considered as theproduct of the transport-chemical reaction coupling processof ore-forming materials (for example, complexes of copper)in discrete, parallel fractures in a porous medium system. Amathematical model of metallogenesis has been established andthe accurate analytical solutions for depicting the transportof ore-forming materials have been worked out. In establishingthe model of metallogenesis and working out the analytical solutions,the following aspects have been taken into consideration: (1)advective transport along fractures; (2) diffusion and longitudinalmechanical dispersion of ore-forming materials (solutes) alongthe fracture axis; (3) diffusion of ore-forming materials fromthe fractures to the wall media; (4) adsorption of ore-formingmaterials on the surface of wall-rock matrices; (5) adsorptionof ore-forming materials within the wall-rock matrices; (6)reduction of the concentrations of solutes due to the chemicalreactions between ore fluids and wall-rock matrices and theprecipitation of ore-forming materials. The general transient solution takes the form of a double integral,which can be evaluated using the Gauss–Legendre quadrature.By comparing the steady-state solutions in the special caseof D = 0 (without dispersion) and of D 0 (with dispersion),a simple criterion can be established, with which one can assessthe importance of longitudinal dispersion along the fracturesystem. Case studies showed that the developing extent of fracturesin the system would exert a great influence on the transportrate and distance of ore-forming materials. In case that fracturesare developed at small intervals, ore-forming materials willbe transported along the fracture system over larger distancebecause of the limited capability of the wall rocks to storeore-forming materials. That is to say, larger orebodies wouldbe formed. In the case of higher transport rates of ore fluidsalong the fracture system the longitudinal mechanical dispersionis negligible, but in the reversed case, the longitudinal mechanicaldispersion would exert a great influence on fluid transport.Under such circumstances, the longitudinal mechanical dispersioncould not be neglected. In the normal case of D 0, the steady-statesolutions could provide a potential approach to predicting theultimate distance over which ore fluids of a certain concentrationlevel penetrate along the fracture system, that is, how longan orebody would extend. Analytical solutions can rationallyinterpret the spatial distribution characteristics of strata-boundskarn copper deposits, the rules governing spatial variationsin ore texture and ore grade, as well as other important geologicalcharacteristics of the ore deposits. This work will providea better understanding of the metallogenic mechanism of strata-boundskarn copper deposits widely spread along the Middle-Lower Reachesof the Yangtze River Valley and its adjacent areas in China.     

SIMPLE MEASUREMENT OF RESTITUTION COEFFICIENT OF IRREGULAR PARTICLES

Restitution is an important physical and mechanical property of granular materials. However, measuring its values in instantaneous collisions between particles is very difficult, especially for ore particles of irregular shapes. In this paper, restitution is measured indirectly and statistically with two cameras recording from different angles the trajectories of the ore particles rebounding from a steel plate. The momenta of the particles prior to and after the collision are calculated from the trajectories to give the restitutions of these collisions. The restitution between ore particles is then derived from the restitution of a steel ball with the steel plate measured in the same way. The approach has been proved to be practical and reliable for a variety of ore particles with moderate restitutions.     

Derivations and Automorphisms of the Positive Part of the Two-parameter Quantum Group Ur,s(B3)

We compute the derivations of the positive part of the two-parameter quantum group U_(r,s)(B_3) and show that the Hochschild cohomology group of degree 1 of this algebra is a threedimensional vector space over the base field C. We also compute the groups of(Hopf) algebra automorphisms of the augmented two-parameter quantized enveloping algebra ?_(r,s)~(≥0)(B_3).