热等静压(HIP)技术在超硬工具制造中的应用

本文简介了热等静压(HIP--Hot Isostatic Pressing)的基本原理与HIP压机的基本构造,阐述了将热等静压技术用于硬质合金钎头与金刚石串珠生产的优越性,介绍了国外金刚石串珠生产中采用HIP技术的效果.HIP技术有利于提高硬质合金的密度、抗弯强度、耐磨性与钎头使用寿命.用于金刚石串珠生产有助于串珠胎体致密化,提高胎体对金刚石的把持力、串珠环对钢体的夹持力及串珠使用寿命.     

Parameters influencing full scale sublevel caving material recovery at the Ridgeway gold mine

The literature discusses a number of theoretical, small, and full scale experimental programs, which have aimed at identifying parameters influencing sublevel caving (SLC) material flow behaviour, and therefore ore recovery and dilution. Historically, parameters directly influencing flow behaviour have been found to include the geometry of the extraction layout and drives, sublevel height, blast ring design, material characteristics of the blasted and waste material, and draw control methodology. To date, no detailed analysis of parameters influencing full scale material flow behaviour and recovery in modern SLC mines has been documented in the literature. This paper outlines the analysis undertaken to identify parameters which influence material recovery at the Ridgeway SLC operation. Parameters analysed included those related to drawpoint location, drill and blast design, geology, drawpoint geometry, and draw control. To identify parameters influencing recovery, a Self-Organising Map (SOM) technique was adopted. SOM is considered an ideal tool for analysing complex geological and mining datasets, and for extracting relationships and patterns that typically are not evident by other means. The SOM analysis indicated that a number of drill and blast design parameters were directly or inversely correlated to material recovery at the Ridgeway SLC operation. Blasting parameters dominated correlations with recovery when compared to drawpoint and geological parameters.     

The oxidation resistance and ignition temperature of AZ31 magnesium alloy with additions of La2O3 and La

We investigate the oxidation resistance of AZ31 magnesium alloy with additions of La and La oxide (La₂O₃). The contributor is the practical La content in alloy. Both La and La₂O₃ are effective in improving the oxidation resistance of Mg alloys. The samples with La content of ∼ 0.7 wt.% possess the best resistance to oxidation of all. Oxide scale, ignition temperature and oxidation kinetics are analyzed. However, higher La content is detrimental to the oxidation resistance.     

新型浮钨捕收剂CYW-29在柿竹园多金属矿的工业应用研究

为解决湖南柿竹园多金属矿选厂生产中存在的精矿WO3品位较低、黑白钨分选效率不高的问题,研制了新型浮钨捕收剂CYW-29,并在湖南柿竹园多金属矿选厂进行了工业试验,结果表明,CYW-29分选性能优异,钨精矿品位和回收率明显提高,捕收剂用量下降,初步预计选厂每年可创经济效益约1 569万元;CYW-29药剂溶解性能良好、配制浓度较高、可常温配药、尾矿废水COD值低,该药剂使用对矿山企业节能减排、清洁环保生产具有重要意义。     

Mechanical analysis of circular tunnels supported by steel sets embedded in primary linings

A series of analytical studies have been performed to investigate the support characteristics of the steel sets embedded in the tunnel primary lining. The analytical models for various modes of loading on an infinite cylinder carrying uniform line load, carrying uniform surface load, reinforced by a single circular ring and reinforced by equidistant rings are proposed respectively. Comparing the deformation characteristics of the infinite cylinder carrying uniform line load and uniform surface load reveals that for a practical tunnel application, the difference between the deformations induced by line load and equivalent surface load is less than 1.5%. The steel set reinforcements in the primary lining can therefore be represented by plane rings in the cylindrical shell. A study of the infinite cylinder reinforced by a single ring reveals that the most prominent effect of a steel set is attributed to its role as a cantilever fixing. It helps carry a certain length of the surrounding ground both ahead and behind before shotcreting and during shotcrete hardening. A subsequent study of the infinite cylinder reinforced by equidistant rings suggests that if the steel set spacing is smaller than a threshold value, the differences of the total stiffness calculated by the proposed method at the locations of the steel sets and other parts of the liner are negligible. The results obtained by the proposed method and the classical method have negligible differences. If the steel set spacing is larger than a threshold value, the classical method should be used with caution. Besides, the proposed method is more accurate than the classical method for calculating the support characteristics of the composite liner.     

Characterization of hot deformation behavior of Haynes230 by using processing maps

The hot deformation characteristics of Haynes230 has been investigated in the temperature range 1050–1250 °C and strain rate range 0.001–10 s^?1 using hot compression tests. Power dissipation map for hot working are developed on the basis of the Dynamic Materials Model. The map exhibits two domains of dynamic recrystallization (DRX): one occurring in the temperature range of 1200–1250 °C and in the strain rate range of 0.001–0.03 s^?1, which associated with grain coarsening; the other occurring in the temperature range of 1100–1200 °C and strain rate range of 0.001–0.01 s^?1, which are the optimum condition for hot working of this material. The average apparent activation energy for hot deformation is calculated to be 449 kJ/mol. The material undergoes flow instabilities at temperatures of 1050–1100 °C and at strain rates of 1–10 s^?1, as predicted by the continuum instability criterion. The manifestations of the instabilities have been observed to be adiabatic shear bands which are confirmed by optical observation.     

Formation and hydrogen storage behavior of nanostructured Mg2FeH6 in a compressed 2MgH2–Fe composite

The present study focuses on enhancing the yield of Mg₂FeH₆ and its hydrogen storage performances through a novel high-pressure compression approach. For which, MgH₂ and Fe powders are first mechanically milled in a molar ratio of 2:1 and subsequently compressed to a cylindrical pellet. Due to the compression, the yield of Mg₂FeH₆ in the compressed 2MgH₂–Fe pellet (90%) has been increased by 24% as compared to the reference ball-milled powder (66%). The thermodynamic destabilization of Mg₂FeH₆ in the pelletized sample is observed through measuring the pressure-composition isotherms, resulting in the reduced ab/desorption enthalpy for the pellet sample (−68.34 and 75.61 kJ/mol H₂, respectively). The hydrogen uptake and release kinetics of Mg₂FeH₆ is remarkably fast, and it can store/release about 5 wt% H in less than 2.5 min at 400 °C. The faster hydrogen ab/desorption kinetics corresponds to the lower activation energies (36 and 95 kJ/mol H₂, respectively). The excellent yield of Mg₂FeH₆ and its improved hydrogen storage properties for the compressed pellet are primarily attributed to the microstructural modifications upon high-pressure compression, and also the obtained results for Mg₂FeH₆ ternary hydride are linked to the literature data based on theoretical calculations.     

Economic evaluation of common reed potential for energy production: A case study in Wuliangsuhai Lake (Inner Mongolia,China)

Wuliangsuhai Lake is one of the largest wetlands in Inner Mongolia, China, half covered by large and highly productive Common Reed (Phragmites australis) stands. However, benefits from current utilization practices do not cover the costs of harvesting. Against this background, Wuliangsuhai Lake is taken as a case study for the assessment of the potential use of reed biomass for energy production. Taking into account, both the present and the potential reed availability, four scenarios are considered, i.e. (1) a decentralized application in household stoves, (2) a centralized reed supplied combined heat and power gasification, (3) a direct combustion plant and (4) a co-firing in existing coal plants. Two field campaigns have been conducted firstly collect information about the current situation of the reed and coal market and secondly to measure reed above-ground biomass. The suitability of reed for thermochemical conversion processes has been evaluated by means of chemical-physical, calorimetric, and thermal analyses of the samples. The potential energy production is valued regarding the profitability on the current Chinese energy market. Possible subsidies for reed as a renewable resource are taken into account. The evaluation has shown that reed has the potential to act as an energy feedstock. In relation to the considered study site, reed energy use can be profitable on the household level, in CHP combustion plants and in co-combustion. Gasification CHP plants are not economic feasible under current conditions. The results show that reed can be a sustainable alternative to highly health and environment damaging coal.     

Flotation Behavior and Mechanism of Anglesite with Salicyl Hydroxamic Acid as Collector

The flotation behavior of anglesite at different pulp pH levels was studied, with salicyl hydroxamic acid (SHA) acting as collector. The results demonstrated the effectiveness of SHA over a wide pH range. Zeta potential, adsorption, and x-ray photoelectron spectroscopy measurements were carried out to explore the interactions between SHA and anglesite. The results showed that the adsorption of SHA on the surface of anglesite was both chemical and physical. Furthermore, experiments with a bench-scale closed-flotation circuit proved that the collector can effectively recover anglesite from zinc-leaching residues (ZLRs). This work sheds new light on flotation of anglesite, providing a significant contribution to understanding of anglesite flotation and its application for disposal of ZLRs.