Liquid phase sintering and oxidation resistance of WC–Ni–Co–Cr cemented carbides

Fully dense WC–Ni–Co–Cr alloys have been consolidated via sinter HIP processing. Dilatometric tests show that shrinkage undergoes several accelerations and decelerations during heating, a phenomenon likely associated to the heterogeneous distribution of Cr in the binder phase. WC grain growth follows trends similar to those described for WC–Co hardmetals, increasing with the C activity and the amount of liquid phase of the cermets. Finally, the oxidation resistance of WC–Ni–Co–Cr cemented carbides is observed to improve as the metal content increases and the C content decreases. In both cases, the oxide layers present a higher proportion of (Co, Ni)WO₄ tungstates. The oxide scales formed on compositions with low metal content contain a higher amount of WO₃ oxide.     

生物灰水泥固化体的性能改进研究

本文介绍了生物灰水泥固化体性能改进的实验研究结果。针对原固化体的空隙率和抗冲击性能较差，开展了以下三方面的研究：（１）水泥品种选择；（２）水泥外加剂的选择和固化配方研究；（３）水泥添加剂的选择及固化配方研究。     

高水固结充填体的自立

本文从分析自立状态下高水固结充填体的受力情况入手，推导出了高水固结充填体自立的强度计算公式－－高水模型，该模型考虑了暴露长度对充填体自立强度的影响。这是它与其它模型在本质上的不同之处，着重分析了影响充填体强度计算的内摩擦角，高度、长度和宽度等结合加拿大的工业性试验情况进行了实例分析，从而验证了模型的合理性     

干振碎石桩加固大面积回填地基

结合某工程的地基加固，对干振碎石桩的施工工艺、质量控制与检验进行了较详细的阐述。     

Improvements in reliability and serviceability of cemented carbides with wear-resistant coatings

Typical defects in microstructure at a surface-coating interface in chemical vapor deposition coated cemented carbides are described. Results on applying new technologies developed to improve reliability and serviceability of coated cemented carbides are presented. Using WC-based cemented carbide substrates with a uniform, fine microstructure etched before coating eliminates various defects at the surface-coating interface. This results in improvement in serviceability and reliability of the coated cemented carbides in metal-cutting.     

矿山充填技术研究与应用新进展──第七届国际充填采矿大会论文述评

综述了第七届国际充填采矿大会论文集的主要内容,着重介绍充填材料、充填体力学、膏体充填、充填设备与系统的应用现状与最新进展。     

模糊集合在等强度胶结充填材料优化中的应用

采用模糊集合论方法，通过计算机模拟和试验，合理选择尾砂浓度和胶结剂用量。在等强度和一定料浆浓度的前提下，尾砂浆浓度较大，胶结剂用量则较小，且相对成本较低。尾砂浓度和胶结剂用量两集合交集中的元素，即是矿山可选择的在等强度下较合适的尾砂浓度和胶结剂用量。模糊集合论用于胶结充填材料质量决策系统是可行的。     

界河金矿下向胶结充填采矿法试验研究

界河金矿4号矿体属于矿岩很破碎、极易冒落、金属品位高的难采矿体。以往矿山用上向水平分层废石充填法开采时,在安全、资源回收上存在较大问题。因而改用下向胶结充填法。首先进行试验回采,完善回采工艺后再全面推广应用。试验中采用了预埋钢筒形成充填小井的新方法,首创工艺简单实用的充填接顶指示装置。由于使用下向胶结充填法,提高了回采安全性及资源回收率,使损失率降至8％,贫化率降至5％。     

高浓度水泥-尾砂充填料浆沉降性能试验研究

对不同配比的高浓度水泥金级配尾砂充填料浆进行自然沉降试验，分析相关因素对沉降特性的影响。结果表明。水泥含量对充填料浆沉降性能的影响较大。在特定范围内，质量浓度对沉降速度的影响小于水泥含量的影响。于料中水泥含量从0%增加到20%（即灰砂配比0～1：4）。对应试件的沉降速度逐步减小。充填料浆沉降速度越快。沉降水在总用水中所占的比率随浓度和水泥含量的增加而减小，沉降水与料浆体积比也随浓度和水泥含量的增加而减小。对于具体采场来说，若采用合理有效的脱排水设施将泌出的沉降水及时排出，则能够对料浆凝结硬化起到帮助作用。     

Effects of water content,water type and temperature on the rheological behaviour of slag-cement and fly ash-cement paste backfill

The pumping ability and placement performance of fresh cemented paste backfill(CPB) in underground mined cavities depend on its rheological properties. Hence, it is crucial to understand the rheology of fresh CPB slurry, which is related to CPB mixture design and the temperature underground. This paper presented an experimental study investigating the effects of binder type, content, water chemical properties and content, and temperature, on the rheological properties of CPB material prepared using the tailings of a copper mine in South Australia. Portland cement(PC), a newly released commercially manufactured cement called Minecem(MC) and fly ash(FA) were used as the binders added to the mine tailing materials. Various amounts of two different water types were added to the mixtures in the preparation of backfill material slurry. Six different temperatures ranging from 5 to 60 °C were to investigate the effect of temperature on CPB rheology. Overall, the increasing water content and decreasing temperature lead to lower yield stress. Based on the results obtained from the rheological properties of CPB slurry, it was found that at room temperature(25 °C), with regards to the unconfined compressive strength(UCS) performance, the replacement of 4% PC mixed CPB(28 days UCS 425 k Pa) to 3% MC mixed CPB(28 days UCS 519 k Pa), reduced the slurry yield stress from 210.7 to 178.5 Pa. The results also showed that the chemical composition of water affects the yield stress of CPB slurry and that MC mitigates the negative effect of mine-processed water(MW) and thus lead to improve the rheological properties of the slurry. However, the results suggested that the rheological properties of a mixture using MC is very sensitive to the water volume and temperature change. Therefore, using MC in backfill requires better quality control in slump mixing.