Latest ArticlesA kind of silicon monoxide-based anode material coated with layers of lithium titanate and carbon was synthesized by chemical vapor deposition and sol-gel method. The electrochemical measurement shows that with lithium titanate coating at an amount of 3%, the anode material presents good performance, showing that the specific capacity is 1 485.4, 1443.8, 1386.4, 1341 and 1276.2 mAh/g correspondingly at 0.2C, 0.5C, 1C, 2C and 4C rate respectively, and the specific capacity is 1 138.1 mAh/g after 150 charge-discharge cycles at current density of 750 mA/g. The flexible carbon layer can buffer volume expansion of the internal silicon core and improve the conductivity of the material. The rigid lithium titanate can ensure structural integrity of the material. The synergy of two layers of coatings can effectively improve cycle stability, rate performance and reversible capacity of electrode material.
Acid mine drainage (AMD) and a pulp regulator, TY-308, were used combinedly for activation in flotation of highly alkali-depressed pyrite, in which AMD was used to neutralize the pulp alkalinity, and TY-308 used to reduce the negative effect of AMD on flotation. A closed-circuit test on flotation with the process consisting of one-stage roughing, one-stage cleaning and one-stage scavenging yielded a pyrite concentrate grading 48.73% S at 97.93% recovery. Compared with the practice using sulfuric acid as the activator, the sulfur recovery can be increased by 1.34 percentage points. Furthermore, not only the cost for AMD treatment will be significantly reduced, but the safety risk associated with the use of concentrated sulfuric acid can be avoided.
Based on the mineralogy of the high-sulfur sedimentary bauxite ore from Pingguo area of Guangxi, including mineral composition, structural property and mineral dissemination characteristics, three kinds of technical schemes were proposed according to the ore properties, including flotation, reduction roasting plus magnetic separation, and calcination, and then adopted respectively in experiments of desulfurization. The mineralogical study shows that this bauxite ore contains 65.04% Al2O3 with S grade of 5.08%, and the dominant minerals therein are diaspore and pyrite. It is found that the pyrite can be effectively removed by those three processing techniques, and the flotation process can yield an bauxite concentrate with Al2O3 grade of 75.90% and the S grade reduced to 0.49%, which is qualified as the feed material for the succeeding alumina extraction. In this case, it is recommended that the flotation be selected as a pre-desulfurization solution for high-sulfur sedimentary bauxite ore.
Ginkgo biloba biochar-based fertilizer prepared with Ginkgo biloba was used for remediation of heavy metal contaminated soil. After 4 d remediation at 30 ℃ by adding 4% ginkgo biloba biochar-based fertilizer, the stabilization efficiencies of Pb, Cd, and Cu can reach 89.5%, 97.5%, and 74.9%, respectively. It is shown that the contents of acid extractable Pb, Cd and Cu decrease from 43.81%, 60.53% and 65.31% to 12.21%, 52.75% and 60.47% respectively; the contents of reducible Pb and Cd decrease from 11.12% and 36.35% to 10.02% and 33.71% respectively; the contents of oxidizable Pb and Cd decrease from 14.36% and 0.76% to 11.61% and 0.74%, respectively, while the content of oxidizable Cu increases from 11.13% to 14.12%; the contents of residual Pb, Cd, and Cu increase from 30.71%, 2.36%, and 22.33% to 66.16%, 12.80%, and 24.19%, respectively. It is concluded that with strong stability and a good remediation effect at low cost, such ginkgo biloba biochar-based fertilizer shows a good application prospect in remediation of heavy metal contaminated soil.
According to the relative position between interbedded surrounding rock and the peripheral holes, the relationship between bedding planes and the connecting line of the adjacent blastholes was classified into three kinds. Mechanism for bedding planes bringing impact to crack propagation in rocks between blastholes by blasting under typical work conditions (with bedding planes on the perpendicular bisector of the connecting line of blastholes) was explored by the LS-DYNA numerical simulation; and the effect of bedding planes in a different relative position to the connecting line of blastholes on the blasting effect of surrounding rock was also studied. It is found that the propagation speed of blasting vibration waves in sandstone is slightly higher than that in sandy mudstone. Under blasting loads, the surrounding rock above both softer layer and the beddings suffer severe damage. The superposition of two-blasthole blasting vibration wave peaks intensifies the damage to the surrounding rock. The blasting effect is poor when the bedding plane penetrates the blastholes, but the blasting effect is ideal if the bedding plane is on the perpendicular bisector of the connecting line of blastholes.
A kind of polymetallic lead-zinc sulfide ore in Guangxi was taken for experimental research. In view of its characteristics of high zinc and low lead, as well as difficulty in the separation between zinc and lead, a new type of efficient inhibitor JFR-1 was adopted in the experiment. It is shown that the lead-zinc sulfide ore was subjected to a lead-zinc bulk flotation, consisting of one roughing, two cleaning and two scavenging, followed by a separation of lead and zinc, consisting of one roughing, two cleaning and two scavenging, finally resulting in a lead concentrate grading 21.00% pb at 72.82% recovery, a zinc sulfide ore grading 6.96% Zn at 94.21% recovery, and a tailings grading 0.04% Pb and 0.13% Zn with a lead recovery of 10.85% and a zinc recovery of 4.79%. Thus, the enrichment and separation of lead and zinc can be actualized.
Aiming at problems including low content of magnetic iron, fine dissemination size and high content of ferrous silicate in processing of the amphibole-type primary ore in Yuanjiacun Iron Mine, an experimental study was carried out by adopting a pre-concentration process consisting of fine crushing plus dry magnetic pulley separation and a roll grinding plus wet magnetic separation. The pre-enriched concentrate was then processed with a flowsheet including a three-stage grinding, a three-stage low-intensity magnetic separation and a reverse flotation, resulting in an iron concentrate grading 65.66% TFe at 49.31% recovery, with the yield of 21.45%. It is shown that iron resource can be utilized efficiently.
Based on the investigation of occurrence state, fluoride associated with barite was leached with HCl-AlCl3 by using Plackett-Burman design, and influences of HCl concentration, AlCl3 concentration, reaction temperature, reaction time, and liquid-to-solid ratio on fluorine leaching rate were investigated. It is found that the fluorine in barite mainly exists in the form of disseminated and banded fluorite. By using HCl at a concentration of 3 mol/L and AlCl3 at a concentration of 0.4 mol/L, after 30 min leaching reaction of ore sample with grain size of 48-75 μm, liquid-to-solid ratio of 10 mL/g, and stirring speed at 300 r/min, the leaching rate of fluorine can reach 93.20%, and the mass fraction of barite is 95.91%. Results show that all factors that influence fluorine leaching rate are arranged in descending order of importance as follows: reaction temperature > HCl concentration > reaction time > AlCl3 concentration > liquidto-solid ratio.
The effects of sulfuric acid concentration, calcite particle size, sodium dodecyl sulfate (SDS) dosage and flow rate of dynamic fluid on the apparent density of calcite particles during acid reaction were studied. The results show that when the sulfuric acid concentration is 1%, calcite can sustain at the low apparent density state, and the smaller the calcite sizes, the lower the apparent densities. SDS with a concentration of 300 mg/L can enhance the hydrophobicity of calcite, increase effectively the adsorption density and residence time of CO2 bubbles on calcite, and prolong the duration of low apparent density of calcite. Dynamic fluids may accelerate desorption of gas bubbles from calcite, which is detrimental to the reduction of apparent density of calcite during acid reaction process, but the SDS treatment can significantly reduce this detrimental effect. Settling tests show that acid reaction can prolong the settling time of calcite particles, creating favorable conditions for the separation of calcite and non-carbonate minerals by gravity concentration.
Mo (VI) and Cu (II) in aqueous solution were extracted by using an aqueous two-phase system consisting of isodecanol polyoxyethylene ether (E-1006) and ammonium sulfate ((NH4)2SO4) for the first time, and a phase diagram of the system was also obtained. Effects of initial pH of aqueous phase, temperature of system, and concentrations of E-1006 and (NH4)2SO4 on Mo-Cu separation effect were also investigated. The results show that with pH of 2.0, temperature of 313.15 K, and both E-1006 and (NH4)2SO4 at concentration of 150 g/L, the extraction efficiency of Mo (VI) is 96.08% and the separation factor for Mo (VI) and Cu (II) is 5 131.45.