Search

Thermodynamic diagrams of Na-S-Fe-H2O system were constructed to analyze the behavior of sulfur and iron in the Bayer process. After digestion, iron mainly exists as Fe3O4and Fe2O3in red mud, and partial iron transfers into solution as Fe(OH)3-, HFeO2-, Fe(OH)4-and Fe(OH)42-. The dominant species of sulfur is S2-, followed by SO42-, and then SO32-and S2O32-. The thermodynamic analysis is consistent with the iron and sulfur species distribution in the solution obtained by experiments. When the temperature decreases, sulfur and iron can combine and precipitate. Controlling low potential and reducing temperature are beneficial to removing them from the solution. XRD patterns show that NaFeS2·2H2O, FeS and FeS2widely appear in red mud and precipitates of pyrite and high-sulfur bauxite digestion solution. Thermodynamic analysis can be utilized to guide the simultaneous removal of sulfur and iron in the Bayer process.

A Coxiella-like endosymbiont (Coxiella-LE hereinafter) stably infects and influences Haemaphysalis longicornisdevelopment, indicating a mutualistic relationship of Coxiella-LE and ticks. To further elucidate the patterns of growth dynamics and tissue localization of Coxiella-LE in H. longicornis, 16S rRNAhigh-throughput sequencing, quantitative PCR (qPCR), and fluorescence in situ hybridization (FISH) were used in this study. The density of Coxiella-LE varied among different tick life stages, and fed female ticks had the highest density, followed by unfed female and unfed larval ticks. In the four organs that were dissected from fed female ticks, the ovary carried the highest density of Coxiella-LE, which was significantly different from salivary glands, midgut and Malpighian tubules. The high abundance of Coxiella-LE in fed female ticks and in the ovaries of fed female ticks in the bacterial microbiota analyses further confirmed that Coxiella-LE rapidly proliferates in the ovary after blood feeding. The ovaries continued to develop after engorgement and oviposition began on day 5, with a significant decrease in the density of Coxiella-LE in the ovaries occurring on day 7. FISH results indicated that Coxiella-LE is mainly colonized in the cytoplasm of the oocyte and proliferates with oogenesis. Coxiella-LE was expelled from the body with the mature oocyte, ensuring its vertical transmission. In the Malpighian tubules at different days after engorgement, the white flocculent materials were increasing, and the density of Coxiella-LE raised significantly on day 7. Unlike the localization pattern in the ovary, Coxiella-LE was initially distributed in a mass and continually increased during the development of Malpighian tubules until it filled the Malpighian tubules. These findings provide new insights on the growth dynamics and tissue localization of Coxiella-LE in ticks and are useful for further investigation on the interactions of symbiont and ticks .

It is a facile and efficient way to produce grapheme quantum dots (GQDs) through photo-Fenton reaction. However, the fluorescence of the as-generated GQDs is weak. Here, bright yellow-green fluorescent graphene quantum dots (GQDs) were prepared by post-oxidation of the GQDs with H2O2. The fluorescence quantum yields of the post-oxidized GQDs (O-GQDs) increased from 0.08% to 3.3% and the maximum emission wavelength shifted from 450 to 510 nm. The O-GQDs exhibit excitation-independent and pH-dependent photoluminescence behaviors. The increase of the photoluminescence intensity is attributed to the more carbonyl and carboxyl groups after the post-oxidation. The post-oxidation treatment offers a simple pathway to enhance the fluorescence of GQDs.

The leaching kinetics of high-phosphorus iron ores in HCl solution was investigated. The effects of temperature ranging from 27°C to 50°C, particle size from 0.18-1.25 mm and HCl concentration from 0.5 to 3.5 mol·L-1 on the leaching efficiency of phosphorus were determined. The dissolution rates are significantly influenced by the temperature and concentration of acid solutions. The experimental results have been analyzed using the shrinking core model for diffusion control. The calculated apparent activation energy of the process is about 43.48 kJ·mol-1, and a reaction order with respect to HCl is 0.64.

Electrolytic manganese residues containing a substantial amount of manganese are a potential pollution. Removing water-soluble manganese ions from electrolytic manganese residues by hydrometallurgical process was discussed. In the work, the basic property of the electrolytic manganese residues was analyzed. Based on it, we proposed the suitable method to remove Mn2+ from the slag by pollution-free oxidation in alkaline solution. The results shown that the best conditions to remove Mn2+ were pH 10.5, temperature 55 °C, the flow rate of hydrogen peroxide 0.50 mL·L-1·min-1 and agitation speed 250 r/min. At the optimum condition, the removal ratio of water-soluble Mn2+ exceeded 99.9% and the concentration of Mn2+ in the final solutions was about 3 mg/L.

In order to solve the problems of rapid rolling schedule optimization design, a combined method of experience and theory were presented in this paper for rapid regulation design . This study adopted the methods of mathematics link for excel as interface development plug-in interface , excel as a model parameter setting and mathematics as the underlying model calculation and optimization software. The new rolling parameters optimization design is obtain , using the experience of rolling method and the variable rolling force model. The design method of calculation results are accurate, rapid rolling parameters setting, model the characteristics of the freedom of choice

Practical teaching is very important in training innovative and practical abilities of college students. On the basis of nonferrous metallurgy teaching characteristics, practical situation and deficiencies had been analyzed and the teaching reforms in the experiment, practice and design had been proposed. A variety of beneficial attempts have been carried out to strengthen the students engineering consciousness and application ability in the reform practice. Through the reform and practice on the teaching methods, it has reached the aim to cultivate the students and improve the quality of practice teaching.

Removing phosphorus from high phosphorus converter steel slag by hydrometallurgical method was studied in this paper. The influence of different dephosphorizting agents on the effect of phosphorus slag was investigated, and high efficient dephosphorizating agent was found. The effects of reaction time, liquid to solid ratio, stirring speed, reaction temperature and dephosphorizing agent concentration on the impact of dephosphorization were studied. The results showed that on the conditions of the reaction time 40 min, slag particle size <0.147 mm, liquid to solid ratio of 4:1, stirring speed 400 rpm, the reaction temperature 25 ◦C, and dephosphorizing agent concentration 5 mol/L, the optimum dephosphorization results were achieved. The dephosphorization ratio can reach 70%, and the phosphorus content in steel slag decreased from 1.03% to 0.46%, the total iron content increase from 30.676% to above 44%.

The removal of dissolvable Mn2+ from manganese residue was attempted using strong reduction at high temperature. The effects of the several parameters which including roasting temperature in range of 750-1050 ◦C and roasting time range of 60-360 min were investigated. An increase in roasting temperature from 750 ◦C to 1000 ◦C for 90 min increased manganese removal rate from 50.79% to 90.48%. But effect of roasting time on the rate of manganese removal was not obviously, just from 90.06% for 60 min to 94.76% for 360 min at 1000 ◦C.

The acid leaching of spent aerospace material with pollution-free oxidation is discussed. Effect of parameters including initial concentration of hydrochloric acid solution, leaching temperature, reaction time, agitation speed, liquid to solid ratio and concentration of oxidant on valuable element extractions are determined, the optimized conditions are 6 M, 60 ℃, 30 min, 250 r/min, 6:1 and 0.0378 mol•L-1•min-1, respectively. The comprehensive results of experiments show that the extracting efficiency of Co and Cu are over 83% and 98% respectively when optimized conditions were adopted.

According to the law of mass balance and charge balance, the lg[P]T-pH diagram of hydroxyapatite in the system of P-Ca-H2O is plotted on the basis of thermodynamic data at 298K and 373K. The thermodynamics condition of hydroxyapatite decomposition is analyzed by thermodynamic equilibrium diagram. The analysis results show that the pH value of solution is a very important factor for the decomposition of hydroxyapatite, and hydroxyapatite can be decomposed on the acid or alkaline condistions. In addition, reaction temperature also has important effect on the hydroxyapatite decomposition. In the acid solution, low reaction temperature can facilitate the decomposition of hydroxyapatite. But in the alkaline conditions, high temperature is beneficial to the decomposition. On the base of thermodynamics analysis results, the verification experiments are carried out on same decomposition conditions. The experimental results accords with the theoretical analysis. The theoretical analysis can guide the research of removing phosphorus from high-phosphorus iron ores.

Copper and cobalt were extracted from nickel chloride solution with N235. The various parameters considered in this work were N235 concentration, reaction time, phase ratio (O/A) and pH value. The optimum conditions are determined that concentration of N235 in organic phase is 40% (volume fraction), the phase ratio (O/A) is 1:2, pH value is 2~4, chloride concentration is 5.76 mol/L and the reaction time is 4 min. Under the optimized operating conditions, cobalt and copper extracted effectively and the extraction rates at the single stage reached 90% and 97%, respectively. After five stage continuous counter-current process, the concentrations of copper, cobalt, iron in the raffinate are less than 0.0008 g/L，0.008 g/L and 0.0025 g/L, respectively, and the recovery of nickel is higher than 92%. The separation effect is steady and satisfied for the electrolysis.

Based on thermodynamic analysis, the recovery of W, Mo, Cr and V as secondary alloy from high speed steel by silicothermic process were performed. The variables effected the reduction process considered in the study were lime ratio, content of reducing agent and heating effect per unit. The experimental results showed that the recovery of W, Mo, Cr and V as secondary alloy from high speed steel grindings was feasible by silicothermic process. The recoveries of W, Mo, Cr and V were 95%, 95%, 72% and 45% respectively. The quality of secondary alloy was steady and satisfied for steel making.