The effects of electrical comminution on the mineral liberation and surface chemistry of a porphyry copper ore

The surface chemistry and mineral liberation changes of a porphyry copper ore after high voltage pulse (HVP) electrical comminution have been investigated using X-ray photoelectron spectroscopy (XPS) and mineral liberation analysis (MLA). Previous studies suggest that electrical comminution has the potential to improve downstream flotation recoveries, due to increased mineral liberation. However, until now the effects on the surface chemistry have not been investigated in detail.The mineral liberation results showed that chalcopyrite was more liberated in the electrical comminution product than in mechanical comminution, noticeably in the coarser size fractions. The surface chemistry of pure chalcopyrite was investigated, using XPS, and high resolution scans of iron and sulphur showed that both comminution methods led to iron oxidising preferentially leaving behind a passivating film of copper sulphides. However, the HVP product oxidisation was more severe with more iron oxide being produced and further oxidation of the remaining copper sulphides into copper sulphate. An attrition grinding stage may be useful in removing the oxidised layer from the surface of the particles prior to flotation separation. This paper presents a new application of the HVP technology in hybrid procedures using electrical comminution and mechanical grinding to prepare the flotation feed, rather than using excessive pulse energy to fully disintegrate ore to the flotation size. Better liberation and flotation performance were achieved through the hybrid procedures than the comparative mechanical comminution.     

Preparation of ultra-fine copper powder and its lead-free conductive thick film

In this paper, non-agglomerated monodispersed ultra-fine copper metallic powders have been synthesized with chemical reduction method. Fine lead-free glass powders were also prepared by solid synthesis process. Thick film paste prepared by above-mentioned copper metallic powders and lead-free glass powders was applied as conductive paste of MLCC. Mixture of glass and zinc oxide give the thick film a high adhesion strength which is attributed to the rough interface from interfacial reaction between glass and chip, and a good densification. Diffusion of metal between copper thick film and nickel thick film is clear. Ni-Cu solid solution appears under high temperature firing.     

高压水射流技术粉碎原盐的研究

以原盐为被粉碎研究对象,通过对高压水射流粉碎原盐形貌的观察和成分分析、高压水射流原盐粉碎性能分析,以及高压水射流粉碎原盐各影响因素的正交分析,研究表明高压水射流粉碎技术对原盐具有良好的解理性且粉碎效率高、耗能低。各因素对原盐粉碎效果的影响顺序为:射流压力卤水喷嘴直径、料液混合喷嘴直径、靶面形状。     

深过冷Fe76B12Si12超细晶材料的凝固组织与软磁性能

首次采用深过冷加水淬的方法,成功地制备了直径为16 mm的样品,高为15 mm,组织中颗粒平均尺寸约为120nm左右的Fe76B12Si12合金超细晶材料.其磁损耗P1T400和P1T1000分别为普通硅钢片的40%和65%.系统研究了组织类型及Fe2B(Si)相尺度对该合金软磁性能的影响,发现该合金的最佳软磁性能位于Fe2B(Si)相完全粒化的非规则共晶组织区,并且当Fe2B(Si)相尺寸细化至0.36～0.50μm时,其软磁性能随着相尺寸的减小而大幅度改善.对以上结果产生的原因进行了讨论.     

利用震动磨超细粉碎天然羟基磷灰石

本文利用震动磨对羟基磷灰石进行超细粉碎,优选出震动磨超细粉碎的最佳工艺条件。利用震动磨研磨可以得到粒度分布单一的粉体样品,D50为2.001μm。     

ANALYSIS OF DISSIPATIVE STRUCTURE IN MATERIAL COMMINUTION

ＡＮＡＬＹＳＩＳＯＦＤＩＳＳＩＰＡＴＩＶＥＳＴＲＵＣＴＵＲＥＩＮＭＡＴＥＲＩＡＬ　ＣＯＭＭＩＮＵＴＩＯＮＺｈａｎｇ；Ｚｈｉｔｉｅ（ＤｅｐａｒｔｍｅｎｔｏｆＭｅｃｈａｎｉｃａｌＥｎｇｉｎｅｅｒｉｎｇ，ＣｅｎｔｒａｌＳｏｕｔｈＵｎｉｖｅｒｓｉｔｙｏｆＴｅ...     

超微粉碎小麦的蛋白质变化探讨

采用自行设计制造的CH—300型机械冲击式粉碎机对小麦进行粉碎加工、分级，通过工艺参数调整，选出两种加工分级后的产品进行分析，结果表明：加工后的小麦平均粒径可达5．85μm，形貌呈球对称状；其蛋白质含量随粒径变细而增加，当D9小于10μm时，蛋白质含量骤然增大一倍多，从而为小麦的特殊使用要求提供了深加工的途径。     

闭路粉碎流程稳态的循环收敛法计算

对由粉碎作业和分级作业构成的闭路粉碎流程,可用循环收敛法进行流程稳态的仿真计算。根据计算时预设条件的不同,循环收敛计算法可进一步分为恒定回路给矿量和恒定磨机给矿量的两种计算方法。本文讨论了这两种计算方法的原理和公式并给出实施这两种算法的详细步骤。     

冀东鞍山式磁铁矿磨矿动力学研究

通过对冀东鞍山式磁铁矿进行不同磨矿时间下磨矿产品粒度分布试验,研究其磨矿动力学行为.研究表明:通过对粒度范围内多个窄粒级动力学常数的曲线拟合,获得的磨矿动力学方程式对不同磨矿时间下筛上累积产物含量的预测精度较高;磨矿过程中,当磨矿细度大于1 mm时,冀东鞍山式磁铁矿磨矿动力学参数k值随磨矿粒度减小而变小的变化趋势与矿粒越细裂纹越少、磨矿越困难的规律是一致的,而当磨矿细度为-1 +0.5 mm粒级时,存在对硬度较低、较易磨的磁铁矿和辉石的优先选择性粉碎,所以为避免过粉碎、节约磨矿成本,在该类矿石选矿时应采用阶段磨矿阶段选别工艺,将单体解离的磁铁矿及时选出.     

某硅钙质胶磷矿正反浮选实验研究

这是一篇矿物加工工程领域的论文。采用超细粉磨技术处理磷矿,可改变磷矿中含磷矿物的物理化学性质,从而提高磷矿中磷的溶解与释放,使其可作为磷肥使用。搅拌磨机作为超细粉磨设备,用其处理磷矿的可行性与工艺参数对磨矿效果影响的研究尚不完善。本文采用立式搅拌磨机对河北某磷矿进行湿法磨矿实验,粉磨产品的粒度分布通过NKT6100-D型激光粒度仪进行检测,探究磨矿工艺参数对产品粒度组成以及新生成粒级含量的影响,并通过R-R方程将产品粒度参数化分析,确定较适宜的工艺参数。结果表明,在搅拌器转速550 r/min、磨矿浓度65%、充填率60%、料球比0.5和磨矿时间30 min的条件下,获得有效磷含量和枸溶率分别为8.75%和74.03%,颗粒特征参数b为0.371、均匀性系数n为1.426的粉磨产品,可见用搅拌磨机对磷矿进行超细粉磨处理是可行的。