EFFECT OF FINE GRINDING ACTIVATION ON LEACHING BEHAVIOUR OF SCHEELITE CONCENTRATE

The influence of mechanical activation on the leaching behaviour of scheelite was studied bymeans of fine grinding in an attritor and subsequently HCl leaching in presence of PO_4~(3-).Results showed that after fine grinding in the attritor,the reaction rate of scheelitewith HCl-Na_3PO_4 solution was remarkably increased,the extraction of W increased fromabout 8 to 99%.The IR spectra and X-ray diffraction analysis indicated that in addition toan enlargement of surface area the fine grinding action had made also changes of fine struc-ture and reactivity of solid surface,hence the leaching process of scheelite can be carried outunder mild leaching conditions.     

Behavior of calcium silicate in leaching process

1　ＩＮＴＲＯＤＵＣＴＩＯＮＩｎｇｅｎｅｒａｌ ,ａｌｕｍｉｎａｃａｎ ｔｂｅｐｒｏｄｕｃｅｄｅｃｏｎｏｍｉｃａｌｌｙｂｙＢａｙｅｒｐｒｏｃｅｓｓｉｎＣｈｉｎａｂｅｃａｕｓｅｔｈｅｂａｕｘｉｔｅｃｈａｒａｃｔｅｒ ｉｚｅｓｉｎｄｉａｓｐｏｒｅａｎｄａｂｏｕｔ 80 %ｂａｕｘｉｔｅｅｘｉｓｔｉｎｌｏｗｄｅ ｇｒｅｅｏｆｔｈｅｍａｓｓｒａｔｉｏｏｆａｌｕｍｉｎａｔｏｓｉｌｉｃａ(Ａ/Ｓ)ｗｈｉｃｈｖａｒｉｅｓｆｒｏｍ 4ｔｏ 9[1] .Ａｎｄａｂｏｕｔ 4 0 %ｏｆａｌｕｍｉｎａｉｓｐｒｏ ｄｕｃｅｄｂｙｓｉｎｔｅｒｉｎｇ…     

Evaluation of high Ni-Cr-Mo alloys for the construction of sulfur dioxide scrubber plants

Corrosion in wet lime/limestone systems used for flue gas desulfurization in thermal power plants is of great concern. The frequent variations in acidity and in chloride and fluoride ion concentrations experienced by such systems pose a serious threat to the materials of construction. Currently used materials mostly type 316L stainless steel often fail to meet their life expectancy. The present study evaluates the performance of advanced Ni- Cr- Mo alloys 59 and C- 276 in a simulated sulfur dioxide scrubber environment. Accelerated tests showed that high Ni- Cr- Mo alloys have little tendency to leach metal ions such as chromium, nickel, and molybdenum at different impressed potentials. Scanning electron microscopy was used to examine the morphology of pitting attack.     

金属型铸造高铬白口铸铁磨球的复合变质处理研究

研究了复合变质处理对金属型铸造的高铬格白口铸铁磨球组织及性能的影响。结果表明，采用ＲＥ、Ｂ、Ｖ、Ｔｉ元素复合变质处理，可有效细化磨球结晶组织，改善碳化物的形态与分布，并显著提高冲击韧性和耐磨性能。     

高浓度熟料溶出的工艺研究

优化烧结法生产 ,提高产量、节约能耗是氧化铝生产急需解决的问题之一。实现高浓度溶出可以提高精液浓度 ,减少湿法系统物料流量 ,达到提高产能、增加产量、降低成品成本的目的。本文通过对国内外高浓度熟料溶出发展情况和烧结法影响高浓度溶出的因素进行分析研究 ,提出了提高熟料A/S的必要性 ;指出了适合我国条件的熟料A/S大小和生料配方 ;分析了温度和αk 对溶出和分离的影响机理和规律 ;提出了适合高浓度溶出的溶出条件和浓度大小。对生产有一定的指导意义。     

提高高铬白口铸铁磨球冲击抗力的技术关键

当高铬白口铸铁含铬量为18%～28%,Cr/C值是8￣9,铸铁的显微组织是回火马氏体 少量残余奥氏体(<5%) M7C3碳化物,则磨球具有高的冲击韧性和断裂韧性K1C,具有高的冲击抗力,表现出低的冲击剥落量。     

新型硬齿面环面蜗杆传动研究

采用精确磨削TI蜗杆的砂轮，用类似直廓环面蜗杆或平面包络环面蜗杆的磨削方法加工环面蜗杆，使该蜗杆和齿面形状与砂轮曲面相同的蜗轮相配合，形成一种新型蜗杆传动，给出了这种传动蜗杆副齿面的数学模型，并通过计算机仿真得出了这种传动蜗轮齿面上接触线的形状及分布特征，初步分析了其啮合特点。     

我国超细粉碎与超细分级技术的现状及问题

近年来 ,我国的超细粉碎与超细分级技术有很大的发展 ,但在发展过程中存在着一些问题。超细粉体涉及的行业众多 ,但对其粒度的分类至今国内尚无定论。通过调研 ,分析了目前国内超细粉碎设备的现状。对超细粉体分级技术中的干法分级和湿法分级作了比较全面的介绍 ,并对我国超细粉碎与超细分级技术的发展提出了建议     

Guayule seedling response to nitrogen fertilizers

Slow growth and high seedling mortality limit direct seeding establishment of guayule (Parthenium argentatum G.). This study was conducted to assess seedling growth enhancement by the addition of different rates and forms of N fertilizers and Ca salts. Experiments were conducted in a greenhouse with cultivar 593 under both surface and subirrigated conditions using water low in salts (salinity of 0.8 dSm^–1, SAR of 5.0 and 10 mg Ca L^–1). Under surface-irrigated conditions, seedling height and fresh plant weight increased with N application to the irrigation water to 70 mg L^–1. The best seedling growth was observed when (NH₄)₂SO₄ was added in combination with CaCl₂ or CaSO₄. Progressively less growth was observed by addition of (NH₄)₂SO₄ alone, CO(NH₂)₂ plus CaSO₄, CO(NH₂)₂ alone and Ca(NO₃)₂. When seedlings were subirrigated, however, the best growth was observed with Ca(NO₃)₂. Intermediate growth was obtained with (NH₄)₂SO₄ plus CaSO₄ and lowest growth rates with (NH₄)₂SO₄ alone. These differential responses may be explained by the differences in leaching and volatile characteristics of the N forms. Growth enhancement from N and Ca additions increased with time with significant increases 45 days after seeding. Nitrogen application with Ca may be effective amendment in promoting subsequent growth of direct seeded guayule.     

Characterization of nanoporous materials prepared from montmorillonite clay and its application to the decolorization of mare's milk oil

Nanoporous materials have been prepared by leaching the purified montmorillonite clay with sulfuric acid (H₂SO₄) solution with varying concentrations (0.5–2 M) at 80°C for 0.5–4 h. Acid leaching causes partial amorphisation of the clay with depletion of MgO, Al₂O₃, CaO and Fe₂O₃ components mostly from interlayer and octahedral sites. This increases the specific surface area by more than 3 times, i.e. from 49.1 to 157 m²/g. The pore-size distribution curves calculated from the adsorption isotherms of the leached montmorillonite show that most of the pores are in the mesoporous region with their diameter ranging 3–4 nm. This material turns out to be appropriate for bleaching of the mare's milk oil. The chemical and structural changes of the acid-leached montmorillonite are discussed in terms of the decolorization capacity.