利用氟化钠消除蛇纹石对黄铁矿浮选不利影响的机理研究

通过浮选试验、Zeta电位测试、SEM-EDS测试、X射线光电子能谱(XPS)测试研究了氟化钠在蛇纹石/黄铁矿体系中的作用机理。蛇纹石是硫化铜镍矿中的主要脉石矿物,不仅会抑制硫化矿物的浮选,而且会进入浮选精矿使后续的冶炼成本增加,因此需要利用氟化钠来消除蛇纹石对黄铁矿浮选的不利影响。研究结果表明,氟化钠可以显著改变蛇纹石的表面电位,使蛇纹石和黄铁矿由原来的静电吸引变为静电排斥,使黄铁矿在蛇纹石存在条件下的浮选回收率由41.2%提升至82.5%。其机理是氟化钠可以与蛇纹石表面的Mg(OH)_(2)反应生成MgF_(2),减少蛇纹石表面暴露的Mg^(2+),从而改变蛇纹石的表面电位,提高黄铁矿的浮选回收率。

云南某选煤厂浮选精煤焙烧工艺深度降硫研究

经过对云南某选煤厂煤泥进行浮选,获得含硫为1.36%(质量分数,下同)的浮选精煤,其中有机硫含量占全硫含量的82.35%,利用物理分选方法进一步脱硫比较困难.采用低温隔绝空气焙烧方法进行煤泥降硫,研究不同焙烧条件对浮选精煤降硫的影响规律,结果表明:在磷基复合药剂(DP)用量为5%,焙烧温度为450℃,焙烧时间为40 min,焙烧物料球团直径为小于9mm的综合焙烧条件下,浮选精煤中的硫含量降至0.30%以下,降硫效果显著,其他有害元素磷和砷等的含量也较低.

Leaching process and kinetics of manganese in low-grade manganese ore

Manganese was extracted from leaching low-grade manganese ore in sulfuric acid medium. The effects of granule diameter, leaching time, liquid/solid ratio (V/W) and the concentration of sulfuric acid were investigated through orthogonal and single factor experiments. The experimental results showed that the optimal leaching conditions are, size of 0.054mm, 120 minutes of reaction time, 3(V/W) of liquid/solid ratio and 30% of the concentration of sulfuric acid (g/g). Under those conditions, the leaching efficiency is 96.73%. The kinetics of the leaching process is in accordance with the characteristics of fractal reaction.

Flotation mechanism of octylic hydroxamic acid on diaspore

Bauxite resources are widely spread in the earth. However, the effective utilization of this mineral is still under infant. The conventional collector for diaspore mineral is oleic acid. It has three main drawbacks which are highly insoluble, large dosages in bauxite flotation, and low selectivity, which hinder its application in industry. In this research, octylic hydroxamic acid was synthesized, and its collecting ability toward two major minerals in bauxite-diaspore and kaolinite was investigated. The collecting power of various reagents for diaspore are shown as follows: oleic acid<octylic hydroxamic acid; while the collecting power for kaolinite was like this: octylic hydroxamic acid<oleic acid. It is shown that octylic hydroxamic acid has the capability of high collectivity and good selectivity. The optimum pH was determined to be 8 9. Zeta potential test revealed that the anionic collectors-octylic hydroxamic acid and oleic acid had been adsorbed on the surface of diaspore and kaolinite, meanwhile the adsorption for diaspore was more remarkable. By the adsorptive capability and IR tests, the adsorption of octylic hydroxamic acid on diaspore was determined to be a process of chemical absorption, which was greater than that of oleic acid.

Leaching of manganese residue for the preparation of trimanganese tetroxide with a high surface area

The accumulation of electrolytic manganese residue (EMR) has become a serious problem and its recycling will be of great benefit to protect the environment and assist sustainable development. The reusing method was conducted by leaching EMR with sulfuric acid and the optimal leaching condition was 1:3 (g/g) as the ratio of solid to liquid with 20% (g/g) H2SO4 , heating at 90 ℃ for 3 hours, which aims at extracting Mn in a sulfuric acid medium. The produced MnSO4 solution was precipitated by adding alkali and oxidized in aqueous phase. The oxidized products were characterized by various techniques, including X-ray powder diffraction (XRD), Fourier transform infrared (IR) spectrometry, vibrating sample magnetometry (VSM), with Brunauer-Emmett-Teller (BET) specific surface area instrument and laser particle size analyzer. The final products were confirmed to be a single-phase Mn3O4 .

Fractal desulfurization kinetics of high-sulfur coal

The pore structure characteristics of high-sulfur coal from Wansheng in Chongqing have been studied by a nitrogen adsorption method （BET）. The effects of grinding and pre-treating with nitric acid on the inorganic sulfur content of coal have been investigated. Organic sulfur in coal pretreated with nitric acid was desulfurized by using propylene-glycol-KOH （PG-KOH）. Fractal kinetic properties of these two desulfurization procedures were investigated by using fractal geometric theory. The results show that both the specific surface area and pore volume increased with the decrease in particle diameter. The microspore surface of coal had fractal characteristics; the fractal dimension was 2.48. The sulfur content decreased with the decrease in particle diameter by grinding. After pretreatment with nitric acid, the desulfurization ratio （DFR） of inorganic sulfur increased to over 99% and the DFR of total sulfur to over 70%. The desulfurization procedure of inorganic sulfur had fractal kinetic characteristics; its reactive frac- tal dimension was 2.94. The organic sulfur desulfurization procedure by PG-KOH was also tallied with fractal kinetic properties; the reactive fracta! dimension was 2.57. The effect of temperature on the desul- furization ratio of organic sulfur can be described with an Arrhenius empirical equation. The rate constant, pre-exponential factor and the activation energy of the reaction increased with the decrease in particle diameter.

Preparation of strontium ferrite from strontium residue

Strontium ferrite was prepared from Strontium Waste Residue (SWR) as a material. Strontium chloride was obtained by leaching SWR with ammonia chloride, and then SrCl2 was converted to SrCO3. Strontium ferrite (SrFe12O19) was formed by roasting the mixture of SrCO3 and FeCl3 in a proper proportion. The structure and magnetic susceptibility of strontium ferrite were investi-gated. The results showed that strontium conversion ratio increased with decreasing SWR grain diameter. The largest ratio was pre-sented when n(NH4Cl/Sr) was 3.6. What is more, the conversion process coincided with the kinetic characteristics of fractal reaction. The magnetic susceptibility of strontium ferrite decreased with increasing Fe3+/Sr2+ mole ratio and pH. SrFe12O19 exhibited face-centered and cubic closely-packed hexagonal structures. There were the strong diffraction peaks of Fe2O3 in the X-ray diffracto-gram of strontium ferrite. Strontium recovery ratio was 87.0%.

Preparation, Characterization, and Catalytic Performance of MoS2 Photocatalyst

The hydrothermal method was used to prepare MoS2 photocatalyst with the raw materials of MoO3 and KSCN, and the prepared products were characterized by X-ray diffraction(XRD) and scanning electron microscope(SEM). The catalytic performance of MoS2 photocatalyst obtained at different reaction temperatures was studied, meanwhile the effects of different concentrations and different pH on degradation rate of methylene blue(MB) were investigated. The results show that those prepared photocatalyst samples are of nanometer scale, which exhibits better photocatalytic activity. When preparing MoS2 photocatalyst, the higher temperature of the hydrothermal reaction, the greater the photocatalytic performance will be, and the crystallinity can be higher as well. As for degrading MB, the higher the concentration of MB is, the worse the degradation effect will be. The prepared photocatalyst was observed to show better degrading performance for MB solution under acidic condition, when pH was taken into consideration.