磨矿对矿物表面性质和浮选行为的影响

综述了磨矿环境、磨矿介质、外加机械力、磨机类型和助磨剂等磨矿过程中的主要因素对硫化矿和氧化矿颗粒表面性质、矿物浮选行为的影响及机制。结果发现:对于硫化矿,磨矿主要影响颗粒的晶体结构和矿浆电化学性质;对于氧化矿和硅酸盐矿物,磨矿主要影响颗粒晶面暴露程度、反应活性、形状指数及粗糙度等,最终影响矿物的浮选行为。通过对磨矿过程中各种因素的优化,获得具有特定晶体结构、形状参数、特定晶面暴露的矿物颗粒产品,进而实现对矿物浮选及分离行为的精细调控,是未来磨矿研究的重点。     

电化学调控浮选能带模型及应用(Ⅱ)——黄药与硫化矿物作用的能带模型

用能带模型研究了黄药与硫化矿物的作用机理 ,说明了硫化矿物表面捕收剂膜的稳定性与半导体能带结构的关系 ,并推导出黄铁矿Barsky关系式。对矿物表面双黄药解吸作用的研究 ,表明矿物表面双黄药的解吸主要受控于矿物电子能级 ,而半导体矿物边缘能级和费米能级影响矿物表面双黄药的稳定性 ,改变硫化矿物的费米能级或边缘能级可以实现双黄药的解吸。根据电化学浮选抑制的能带模型 ,可开发出高效硫化矿有机抑制剂。     

电化学调控浮选能带模型及应用（Ⅱ）：黄药与硫化矿物作？…

用能带模型研究了黄药与硫化矿物的作用机理，说明了硫化矿物表面捕收剂膜的稳定性与半导体能带结构的关系，并推导出黄铁矿Ｂａｒｓｋｙ关系式。对矿物表面双黄药解吸作用的研究。表明矿物表面双黄药的解吸主要受控于矿物电子能级，而半导体矿物边缘能级和费米能级影响矿物表面双黄药的稳定性，改变硫化矿物的费米能级或边缘能级可以实现双黄药的解吸。根据电化学浮选抑制的能带模型，可开发出高效硫化矿有机抑制剂。     

浮选药剂的亲固能计算

在浮选体系下，药剂和矿物的作用不仅和键合原子有关，还和矿物表面相邻原子、药剂亲固基团以及介质水分子有关。在此模型下提出了药剂亲固基团和矿物表面作用能的计算公式，利用这一公式可定量研究矿物表面极性、药剂分子极性和介质水分子对浮选药剂亲固能的影响。研究结果表明，浮选介质分子水影响药剂和矿物表面作用能的强弱，对于极性较小的矿物（如硫化矿物），其表面和药剂亲固基团的作用能与基团电负性成反比，基团电负性越小，作用越强；对于极性较大的矿物（如非金属矿物），其表面和药剂亲固基团的作用与基团电负性成正比，基团电负性越大，作用越强。     

羧甲基纤维素对层状镁硅酸盐矿物浮选的抑制与分散作用

通过浮选实验、润湿接触角测量和Zeta电位测试,考察滑石、绿泥石和蛇纹石3种层状镁硅酸盐矿物的可浮性及其对金川镍矿中的硫化矿物-黄铁矿浮选的影响,并研究羧甲基纤维素(CMC)对3种层状镁硅酸盐矿物浮选的抑制与分散作用.结果表明;3种镁硅酸盐矿物表面性质与可浮性不同,对硫化矿浮选的影响方式与机理也存在区别:蛇纹石天然可浮性较差,但由于静电作用易与黄铁矿发生异相凝聚,降低黄铁矿的可浮性进而影响其回收率,CMC可通过调整矿物表面电性而起到分散作用;滑石与绿泥石并不影响黄铁矿的可浮性,但由于其天然可浮性相对较好,易进入精矿增加MgO杂质含量,CMC能调整矿物表面润湿性而抑制其浮选.     

超声预处理对锂辉石矿物浮选分离的影响

采用NaOH溶蚀与超声波耦合机械搅拌相结合的预处理技术对锂辉石、石英和长石进行浮选前预处理,以探究超声预处理对锂辉石矿物浮选分离的影响。通过开展单矿物浮选和人工混合矿浮选试验,比较超声波耦合机械搅拌与传统机械搅拌两种预处理技术的优缺点;为了探明预处理技术的作用机理,对经不同预处理后的矿样进行了SEM、吸附量测试和XPS分析。结果表明：超声预处理后,锂辉石与长石、石英之间的可浮性差异进一步增大,-0.074+0.038 mm粒级的锂辉石人工混合矿精矿浮选回收率最高可达48.23%,分选效率达到44.27%;相较于传统机械搅拌预处理,超声波耦合机械搅拌预处理的浮选效果进一步提高。介入超声波预处理后可进一步改变锂辉石矿物表面形貌,并促进更大范围的表面溶蚀,从而增加矿物表面药剂吸附,且超声波耦合机械搅拌预处理后的锂辉石比传统机械搅拌预处理后的锂辉石具有更强的NaOL吸附能力,可见超声预处理技术对锂辉石、石英和长石的浮选分离具有显著的促进作用。     

硫化矿物表面天然疏水性的密度泛函理论研究(英文)

采用密度泛函理论研究了水在硫化矿物表面的吸附以及硫化矿物的天然可浮性。为了排除氧气和其他因素的影响,所有的计算模型都是在真空环境下建立的。水分子是在黄铁矿与闪锌矿的表面,而不是在水里。对于方铅矿、辉铜矿、辉锑矿和辉钼矿,水分子是在水里,而不是在这些矿的表面。另一方面,黄铁矿表面亲氮气而不亲水,而闪锌矿表面不能吸附水。结果表明,方铅矿、辉锑矿、辉铜矿及辉钼矿是疏水的,而闪锌矿是亲水的。黄铁矿具有一定的亲水性,但是它更倾向于亲气,这是因为黄铁矿与水的作用要比与氮气的作用弱。因此,黄铁矿、方铅矿、辉铜矿、辉锑矿及辉钼矿都具有天然可浮性。     

硫化矿的氧化与浮选机理的量子化学研究

本文用量子化学的CNDO/2方法计算了方铅矿和黄铁矿表面、氧的吸附以及氧化表面与乙基黄药相互作用体系.讨论了这两种矿物的表面电子结构,描述了方铅矿浮选的离子交换机理和黄铁矿浮选的双黄药分子吸附机理;研究了氧在硫化矿捕收剂浮选和无捕收剂浮选中的重要作用.     

电化学调控浮选能带模型及应用（Ⅰ）：半导体能带理论及模型

根据硫化矿物的半导体性质以及硫化矿浮选的电化学特性，得出了半导体矿物－溶液界面的电子能级分布能带模型。提出采用矿选常用参数，即矿物静电位和矿物颗粒表面动电位来计算硫化矿物的费米能级和边缘能级的简便方法。矿物的禁带宽度、功函数、药剂吸际、溶液性质以及离子强度等因素能够改变矿物边缘能级的大小。     

矿物的解理性质及表面能：各向异性的表面断裂因素

利用Materials Studio软件计算研究几种属于立方、四方、六方或单斜晶系等不同晶系的典型硫化矿、氧化矿和含氧酸盐矿物的表面断裂键性质,分析这些矿物的解理特性,并建立表面断裂键密度与表面能的关系。结果表明：表面断裂键性质可以用来预测大部分矿物的解理特性,预测结果与文献报道一致。对于某种矿物,表面断裂键的密度与表面能成正比,决定系数R^2皆大于0.8,表明表面断裂键的密度大小是决定表面能的关键因素。同时,表面断裂键的数目可用来预测矿物表面的稳定性及表面原子的反应活性。     

Milling media and alloying effects on synthesis and characteristics of mechanically alloyed ODS heavy tungsten alloys

Oxide dispersion strengthened (ODS) tungsten heavy alloys produced by mechanical alloying exhibit high creep strength at elevated temperatures and good penetration performance. The effect of process parameters during mechanical alloying is important in determining material properties. In this study, we have examined different grinding media and have varied the composition of alloying elements to investigate their effect on grinding performance and microstructure evolution. The composition of the milled powders can be changed due to the wear of the grinding media and can form different phases, which results in a significant effect on microstructural development and material properties. Our results show that alloys milled by a stainless steel grinding media encourage the formation of iron–tungsten carbides and iron–tungsten intermediate phases, which deteriorate the material densification and ductility. Conversely, the use of a tungsten carbide grinding media leads to an extreme refinement of the milled powders, whereby alloys form a uniform microstructure with a γ(Ni, Fe) phase configuration. This phase provides sufficient binding strength between the tungsten particles, such that the relative density and ductility of the materials were found to have been significantly enhanced.     

磨削对氧化膜去除质量影响的稳定性与敏感性

目的研究磨削参数对电化学加工氧化膜去除质量的影响规律,以及各参数对氧化膜去除质量影响的稳定性和敏感性。方法在试件表面形成均匀一致,无缺陷电化学加工氧化膜的前提下,借助自主搭建的机械磨削实验平台,分别研究磨粒尺寸、工件速度、磨削压强和加工时间对氧化膜去除质量的影响,使用精密电子天平和扫描电子显微镜对实验前后的试件进行测量,结合稳定性与敏感性分析理论对实验结果进行分析。结果不同的加工参数对氧化膜去除程度的影响不尽相同,氧化膜既存在不完全去除的现象,也存在完全去除的现象。扫描电子显微镜结果也显示,不同尺寸的磨粒对氧化膜的破坏程度不同,其表面氧化膜的沟槽深浅不同。结论受氧化膜硬度低、容易去除和基体金属硬度高、不容易去除的影响,氧化膜去除质量随着工件速度和加工时间的增加呈现三次曲线的规律增加,随磨削压强和磨粒尺寸的增大呈线性增加趋势。磨削参数对氧化膜去除质量影响的稳定性与敏感性不同,而且在电化学机械加工生产应用中不改变磨削工具,所以在磨削参数相对值较低的区间,其对去除质量影响的稳定性由大到小(敏感性由小到大)为:磨粒尺寸、加工时间、磨削压强、工件速度。在磨削参数相对值较高的区间,稳定性由大到小(敏感性由小到大)为:磨粒尺寸、磨削压强、工件速度、加工时间。加工中优先选择稳定性高(敏感性低)的参数作为调整电化学机械加工效果的主要因素,可在提升经济性的同时,提高加工精度。     

High energy milling on tungsten powders

Nanocrystalline tungsten powders were produced by high energy mechanical milling, using both tungsten carbide (WC) and tungsten (W) balls as grinding media. X-ray diffraction study indicated that the lattice parameter of tungsten decreased (from 3.162 to 3.149 Å) with increasing milling time from 0 to 15 h. Considerable decrease in particle size was observed in both W and WC grinding media after 15 h of milling duration. Rietveld analysis of the X-ray data along the Williamson-Hall plots revealed that the crystallite size also decreased with increasing milling time. Chemical analyses showed that the total amount of cobalt and carbon in the milled samples were higher in WC grinding media, as compared to W grinding media. The sintered density increased from 80% to 98% from as received to milled tungsten powders, when sintered at 1790 °C. The mechanical properties of as sintered alloys were evaluated and were found to be strongly influenced by the milling time and grinding media.     

APPLICATIN OF ATTRITION GRINDING IN ACID LEACHING OF NICKEL SULFIDE CONCENTRATE

ＡＰＰＬＩＣＡＴＩＮＯＦＡＴＴＲＩＴＩＯＮＧＲＩＮＤＩＮＧＩＮＡＣＩＤＬＥＡＣＨＩＮＧＯＦＮＩＣＫＥＬＳＵＬＦＩＤＥＣＯＮＣＥＮＴＲＡＴＥ①ＬｉＸｉｍｉｎｇ，ＣｈｅｎＪｉａｙｏｎｇＩｎｓｔｉｔｕｔｅｏｆＣｈｅｍｉｃａｌＭｅｔａｌｕｒｇｙ，ＴｈｅＣｈｉ...     

螺旋桨金刚石砂带磨削试验研究

以船用螺旋桨为研究对象，提出一种利用电镀金刚石砂带磨削螺旋桨的方法，并试验分析影响螺旋桨表面粗糙度的各个工艺因素。通过单因素试验研究磨削压力、砂带线速度和磨削进给速度对表面粗糙度的影响，并得到工艺参数的最优水平组合:磨削压力15 N，砂带线速度30 m/s，磨削进给速度20 mm/s；锆刚玉砂带与金刚石砂带在相同工艺参数下对螺旋桨表面粗糙度的影响规律基本一致，但金刚石砂带具有更长的寿命，增幅为125%。      

基于空化效应的功率超声珩磨再生型颤振研究

功率超声珩磨加工过程中的颤振影响因素很多,不仅包含物理磨削过程和机械振动环节,还包含了高频振动和超声波传动系统,是一个非常复杂的复合振动系统。通过建立珩磨颤振动力学模型,重点研究珩磨中空化泡溃灭产生辐射声压对再生型颤振的影响,结果表明:决定功率超声珩磨再生型颤振的主要原因为磨削厚度;空化泡溃灭产生的辐射声压会加剧系统颤振的频率,但对系统颤振的时域图变化趋势和振幅的大小基本没有影响。     

Fine grinding of silicon wafers: designed experiments

Silicon wafers are the most widely used substrates for semiconductors. The falling price of silicon wafers has created tremendous pressure to develop cost-effective processes to manufacture silicon wafers. Fine grinding possesses great potential to reduce the overall cost for manufacturing silicon wafers. The uniqueness and the special requirements of fine grinding have been discussed in a paper published earlier in this journal. As a follow-up, this paper presents the results of a designed experimental investigation into fine grinding of silicon wafers. In this investigation, a three-variable two-level full factorial design is employed to reveal the main effects as well as the interaction effects of three process parameters (wheel rotational speed, chuck rotational speed and feed-rate). The process outputs studied include grinding force, spindle motor current, cycle time, surface roughness and grinding marks.     

Improvement of hydrogen-storage properties of MgH2 by addition of Ni and Ti via reactive mechanical grinding and a rate-controlling step in its dehydriding reaction

In a shift from prior work, MgH₂, instead of Mg, was used as a starting material in this work. A sample with a composition of 86 wt% MgH₂-10 wt% Ni-4 wt% Ti was prepared by reactive mechanical grinding. Activation of the sample was completed after the first hydriding cycle. The effects of reactive mechanical grinding of Mg with Ni and Ti were discussed. The formation of Mg₂Ni increased the hydriding and dehydriding rates of the sample. The addition of Ti increased the hydriding rate and greatly increased the dehydriding rate of the sample. The titanium hydride, TiH_1.924, was formed during reactive mechanical grinding. This titanium hydride, which is brittle, is thought to help the mixture pulverized by being pulverized during reactive mechanical grinding and further to prevent agglomeration of the magnesium by staying as a hydride among Mg particles. A rate-controlling step for the dehydriding reaction of the hydrided MgH₂-10Ni-4Ti was analyzed by using a spherical moving boundary model on an assumption that particles have a spherical shape with a uniform diameter.     

Ultra-fine grinding of inorganic powders by stirred ball mill: Effect of process parameters on the particle size distribution of ground products and grinding energy efficiency

A series of wet grinding experiments have been carried out using a stirred ball mill to systematically investigate the effect of processing conditions on the final particle size distribution and grinding kinetics. A sub-micron particle size down to 350 nm was achieved, while the grinding energy efficiency or enhanced grinding rate was shown to be improved with the addition of grinding aids and with the use of smaller grinding media. A simple exponential relation was then proposed to quantitatively describe the observed grinding behavior by introducing the production rate constant,K. It is suggested that by usingK as a guideline, ways of improving the grinding energy efficiency can be established, e.g. use of smaller grinding media, choosing larger particle size class materials, etc.     

水溶性造孔剂在超薄树脂切割砂轮中的应用

为进一步提升超薄树脂切割砂轮的自锐性能和排屑容屑能力,在切割砂轮中加入水溶性造孔剂NaCl,研究其含量对超薄树脂切割砂轮的微观形貌、力学性能及切割性能的影响。结果表明:当造孔剂添加体积分数为10%时,砂轮中的孔隙均匀适中,其切割效率最高,进给速度最高可达20 mm/s。但加入造孔剂会对砂轮的抗折性能和切割寿命产生一定影响,造孔剂含量越高,抗折性能越低,切割寿命越短。