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.     

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).     

重晶石和铁矿粉对套管/钻杆摩擦副摩擦磨损性能的影响

利用MG-200型高温高速摩擦磨损试验机对比考察了钻井液中所含的重晶石和铁矿粉对套管和钻杆试件摩擦学性能的影响，并采用扫描电子显微镜观察分析了磨损表面形貌，探讨了其磨损机理．结果表明，钻井液中的重晶石使得套管／钻杆磨损机理由严重塑性流动转变为磨粒磨损；而随着钻井液中铁矿粉含量的增大，磨损机理由磨粒磨损转变为粘着磨损和疲劳磨损；当铁矿粉含量较低时，采用较高的转速更有利于减小摩擦。     

碳质金矿中金的化学物相分析方法改进

为了解决碳质金矿金化学物相分析结果与选矿试验结果不符的问题,基于岩矿鉴定和测试结果对分析流程进行改进。方法改进后测试项目包括裸露金和半裸露金、有机碳石墨包裹金、碳酸盐包裹金、褐铁矿包裹金、黄铁矿包裹金、石英和硅酸盐包裹金6项。有机碳石墨包裹金选用Na_2S_2O_3–CuCl_2–NH_4OH–NH_4Cl体系为浸金剂,取代I_2–NH_4I体系,该体系中金的测定采用铜置换原子吸收法。裸露金半裸露金、有机碳石墨包裹金和黄铁矿包裹金的相和为82.34%,与选矿试验金精矿实际回收率(75.83%)基本吻合。改进后的方法适合碳质金矿金化学物相分析。     

硝化后熔融制样法——X射线荧光光谱同时测定锰矿中主、次元素

采用X射线荧光光谱法同时测定锰矿中Mn,SiO₂,Fe,P,Al₂O₃,CaO,MgO和S等8个组分。因锰矿熔融制样过程中产生气泡现象严重,影响到测定的准确性和重现性,文章提出了先加硝酸破坏锰矿样品中的有机物,然后用12∶22混合熔剂在1 000 ℃熔融制样的方法,解决了锰矿熔融制样过程中有机物挥发产生大量的气泡导致熔剂飞溅的问题,消除了试样的粒度效应和矿物效应,同时也解决了硫元素在制样过程中容易挥发的难题。对熔剂、熔融时间、硝酸加入量等制样条件进行了选择,并采用可变理论α系数法校正基体的吸收增强效应,扩大了测定线形范围,进行了方法的精密度及准确度试验。与化学法对比,本法测定锰矿中各组分的定量分析结果令人满意,方法准确、快速、简便。     

云南勐满微细粒型金矿床稀土地球化学特征

云南勐满金矿床是“三江”褶皱系南端一个微细粒红土复合型金矿床,对其微细粒型金矿稀土元素地球化学方面进行了研究。结果表明,矿石与围岩的稀士元素总体特征非常相似,说明两者稀士来源基本一致。     

多金属结核/结壳中稀土元素的富集特征及其资源效应

多金属结核/结壳是海洋中最重要的固体沉积矿产之一,蕴藏丰富的铁、锰、铜、钴、镍等金属元素,也是稀土元素的富集体.利用等离子质谱仪/光谱仪对太平洋、大西洋、印度洋及南海北部海多金属结核/结壳11个样品25份试样的稀土含量进行了分析,多金属结核/结壳中稀土平均含量为1265 57×10-6,其中结核平均含量为1096.96×10-6,结壳平均含量1623.88×10-6,人人超过地壳和玑积岩的平均含量.稀土元素的富集主要受控于结核/结壳中铁、锰氧化物及粘土矿物对海水和沉积物中稀土元素的吸附作用,Ce元素高度富集,使其成为多金属结核/结壳矿产开发中可能最先利用的稀土元素之一.     

Investigation on the evolution characteristics of bed porous structure during iron ore sintering

To better understand the evolution characteristics of bed porous structure during iron ore sintering, X-ray computed tomography scanning technology was used to analyze the pore parameters in different areas of the sintering bed. A pore skeleton structure model was established to study the characteristics of the airflow channels in different zones. The absolute permeability of different areas was calculated through simulation, and the corresponding streamline and pressure drop distribution were analyzed. The results show that the porosity of raw material zone, high-temperature zone, and sintered zone increases gradually, which are 37.69%, 46.41%, and 55.57%, respectively. The absolute permeability calculation results of the raw material zone and sintered zones are 792.49 μm² and 20560.80 μm², while the tortuosity is 1.77 and 1.45, respectively. Compared with the raw material zone, the flow streamline in the sintered zone is thicker and denser, the airflow resistance and the pressure drop are minor.     

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.