宜阳矿采矿工作面由纵采改为横采的实践

通过对采场工作面开采方法的改进，实施贫富兼采，合理配矿，取得最佳经济效益。     

小煤柱综采放顶煤工作面瓦期涌出分析及治理

针对小煤柱开采时相邻已采工作面采空区的瓦斯涌入本工作面,造成工作面瓦斯涌出量增大,工作面上隅角瓦斯浓度高,影响工作面安全生产的情况,对小煤柱综放工作面瓦斯涌出情况进行了测定、分析,并针对性地提出了相应的瓦斯治理方案,取得了明显的效果.     

某煤矿高档普采工作面顶板管理方式及适用条件分析

介绍了某煤矿高档普采工作面应用2.6 m长整体箱型顶梁配合Dz-25单体液压支柱管理顶板的方法,并结合该矿的具体条件阐明了此种顶板管理方式的优越性,从矿压理论上分析了它的适用条件,认为在一般机械化采煤工作面还是我国发展重点的现阶段,为提高机采工作面各项枝术经济指标,条件适合的矿井,有必要推广和使用此种顶板管理方式。     

线性规划法在氧化铝工业供矿中的应用

通过对线性规划法确定的优化供矿方案与实际供矿情况的对比 ,说明线性规划的优化供矿方案可以成熟地应用于氧化铝厂供矿计划的编排和实际供矿安排中 ,其经济效益和稳定指标作用十分突出。其实用性在优化生料浆的配制方面也将发挥更大作用     

山西铝厂铝矿配矿工艺研究（上）

简介国内外矿山配矿概况,略述山西铝厂孝义铝矿与配矿有关的地质条件和采矿方法。配矿试验前三年来,该矿供矿品位按A/S=4.3±0.3和±0.2,F/A=0.1±0.016来衡量,平均合格率仅27.4～30.9％。配矿方案1:矿石落地方案,即采场初步配矿 堆场平铺直取均化 (破碎后)碎矿在矿仓优化组合配矿;配矿方案2:矿石不落地方案,即采场分采分堆 破碎原矿槽按比例搭配出矿 矿仓优化组合配矿。两方案配矿合格率均达100％,A/S的标准差分别为O.1069和0.1261,F/A的标准差分别为0.00846和0.00777,前者配矿和均化效果较好,后者生产环节较少,可省经费0.5元/t,亦可满足配矿要求。说明为配矿工艺服务的计算机质量跟踪管理和信息反馈系统,以及矿山CAD工作站和适应铝土矿复杂多变特点的软件系统。配矿的经济效益可观,仅按1992年的计划产量计,矿山1年可增加收入118万元,氧化铝厂1年就可多创效益1555万元。     

用电子计祘机选择最优供矿方案

问题的提出在铝土矿矿山的生产实践中,经常迂到由数个矿点同时向一个氧化铝厂供矿。为了满足氧化铝厂对矿石质和(曰一力)的要求,必须制定一个较长时期的供矿方案(供矿规划)。过去,制定供矿方案的一般方法,是通过反复的试祘来     

银厂坡矿地下开采通风系统

银厂坡矿段地下开采采用斜坡道开拓方式,两侧抽出、中央压入式通风,按照炮烟排放、工作面开展等计算井下开采通风需求量,对应选取安装通风设备设施,形成一套较为完整、科学的机械通风系统.针对银厂坡矿段地下开采通风存在的一些问题,作了原因分析,采取了有效的解决措施,确保了井下作业通风安全.     

大型矿热电炉厂的供电设计

随着矿热电炉大型化的发展,电炉变压器容量的不断提升,矿热电炉的供电设计出现了一些新问题.通过在大型矿热电炉设计中的经验,阐述大型矿热电炉供电设计中所出现的新问题及处理方案.     

皖西某铜矿L-23矿体开采出矿系统的改进

通过对皖西某铜矿L-23矿体开采出矿系统多方案进行优化论证,确定选择方案1为最优改进方案。     

麦坝矿区房柱法开采矿块回采顺序优化

针对缓倾斜中厚矿体开采过程中工作面顶板管理困难的问题,本文以麦坝矿区小长冲河矿段矿体为研究对象,结合其采矿方法和矿体赋存特征,采用有限元数值模拟软件对1325中段矿体回采顺序进行模拟研究,从应力、位移、安全率及塑性区分布4个方面对不同回采顺序进行比较分析,从而确定合理的开采顺序。现场应用取得良好效果,试验段巷道顶底板移近量控制在114 mm,工作面顶板活动得到有效控制,保障了矿山安全生产。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.