Solubility of Nb2O5 and leaching behaviors of Nb and Ta from niobite in KOH solution have been investigated in order to develop an alkali hydrothermal leaching process of Nb and Ta. The solubility of Nb2O5 was measured in the range of 40 °C to 200 °C at various molar ratios of K2O to Nb2O5(n(K2O)/n(Nb2O5). It has been found that Nb2O5 shows the maximum solubility at the solution composition of n(K2O)/n(Nb2O5)=4/3 at a given temperature; the rise of temperature increases the solubility of Nb2O5 below 120 °C, but decreases it above 120 °C. The leaching behaviors of Nb and Ta were studied in the range of 150 °C to 250 °C and 0.1 MPa to 5 MPa. With the rise of temperature, the leaching degree increases when the leaching temperature is below 200 °C, but it decreases when the leaching temperature is above 200 °C. The maximum leaching degree is about 90% at 200 °C. It was proved that the alkali hydrothermal leaching process is effective for the recovery of Nb and Ta from niobite concentrate.
For the purpose of developing an alkali leaching-solvent extraction directly from alkali solution process, the extraction of niobium from alkali solution by long-chain alkyl quternary ammonium salt (methyltrioctylammonium chloride R4NCl) in toluene was investigated. The experiments were carried out under conditions of 25 °C, Nb(V) concentration 0.01 mol/L, pH 10.7–13.8, R4NCI concentration 0.02–0.14 mol/L. It has been found that the distribution ratio of niobium increases with increasing R4NCl concentration and with decreasing KCl concentration, but it shows maximum value at pH value of about 12 and decreases below or above this pH value. Distribution ratio of niobium goes up to over 1 000 in appropriate conditions, and so it has been proved that R4NCl is an effective extractant for extraction of niobium from alkali solution.
Methyl isobutyl ketone(MIBK) is widely used as extraction agent in hydrometallurgy. As it has a definite solubility in water, so when using MIBK as extraction agent, there will be MIBK in stripping solutions inevitably, which not only pollutes working conditions, but also affects the quality of ultimate product. In order to remove MIBK from aqueous solutions, the means of flat vacuum membrane distillation(VMD) is studied in the paper. The area of the membrane used in the study is 0.02 m2, the initial volume of feed is 2 L, each experiment was conducted over a time period of 60–120 min. The influences of the factors such as temperature(34.8–55.0 °C); pressure in the permeate side(10.67–14.67 kPa) and feed flow rate(27.8–69.4 mL/s) were experimentally studied. Increasing the temperature or reducing the pressure in the permeate side results in a faster removal of MIBK; however there is a decrease in removal factor β, increasing the feed flow rate results in a faster removal of MIBK and an increase of removal factor β, especially in the range of lower flow rate. The study indicates that the aim of MIBK removal and recycle from dilute aqueous solutions can be achieved by VMD.
In order to develop an effective MIBK removal method of H2TaF7 solution in tantalum extraction process, MIBK removal from aqueous solution by the aeration method was investigated by using an aeration column with the dimensions of 78 mm in inner diameter and 1 100 mm in length. The effects of aeration conditions on aerating efficiency were investigated in the ranges of temperature 303–333 K, airflow rate 50–300 L/h, volume of solution 1 600–3 200 mL. Aerating efficiency increases with the increase of temperature and airflow rate. MIBK in aqueous solution can be removed from 0.058 mol/L to 0.002 mol/L at 50°C, airflow rate 200 L/h, volume of solution 2 400 mL and aeration time 1h. The experimental results show that MIBK can be removed effectively from aqueous solution by the aeration method.
In order to develop an energy-saving electrodeposition process of copper, the electrodeposition of copper in copper sulfate solution by the ion-exchange membrane primary cell (IMPC) method has been studied. The experiments were carried out in an ion-exchange membrane primary cell with dimensions of 200 mm in length, 52 mm in width and 90 mm in height. The influences of temperature (294–323 K), interval between the anode and cathode (1.5–3.5 cm), mass concentrations of Cu2+ (6–40 g/L), H2SO4 (0–120 g/L) and Fe3+ (3–9 g/L) in catholyte and solution flow rate (0–8 cm/s) on current density and current efficiency were investigated experimentally. The current density increases with the increase of temperature and concentrations of Cu2+ and H2SO4 in catholyte. Cathode current efficiency decreases with the increase of concentration of Fe3+ in catholyte and anode current efficiency decreases with the increase of temperature. The high-quality cathodic copper can be obtained and the current density of membrane can be higher than 150 A/m2 and the current density of cathode can be higher than 300 A/m2. The experiment results show that IMPC method is effective for electrodeposition of copper.
By comparing the adsorption capacity of several kinds of resins, D363 resin is regarded as the most suitable one for removing lead from nickel sulphate electrolyte. The effects of pH, temperature and contact time on exchange adsorption during removing trace lead from industrial nickel sulphate solution with D363 large-pore weak alkali anion-exchange resin are discussed. Optimum conditions of adsorption of lead from nickel electrolyte by D363 resin are at room temperature, pH 1–2, contact time 30 min.
In the process of nickel production by diaphragm electrolysis, the quality of the product has been tremendously affected by the content of zinc in the nickel electrolyte. Removing zinc from nickel electrolyte by ion-exchange is studied in the paper. Resin D201 is selected as the resin for zinc removing. Effects of the operative parameters, such as temperature, pH value and the contact time on zinc adsorption are observed and the desorption feature of the zinc-loaded resin is inspected. The results show that macroporous anion-exchange resin D201 has excellent adsorption and desorption properties. Its breakthrough capacity and saturation capacity in zinc adsorption reach 0.81 g/L of zinc and 1.16 g/L of zinc respectively, when the operative temperature is 60 °C and the contact time is only 5 min. In addition, compared with gel type IER 201 × 7 used industrially nowadays, this resin has better wearability and greater intensity.
The flow stress behavior of Cu13Zn alloy was investigated by compression tests carried out at 650 °C, 700 °C, 750 °C, 850 °C, and constant strain rates of 0.05 s−1, 0.1 s−1, 0.5 s−1, 1 s−1, 5 s−1, respectively. The results show that the flow stress increases with the increase of strain and reaches a steady-state stress, and the saturated stress (σs) increases with the increase of the strain rate and the decrease of temperature. Flow stress curves of the alloy deformed at elevated temperatures can be simulated effectively by the model proposed by Zhou and Clode, and the flow stress is described as a function of strain, strain rate and temperature. Material constants values are: Q=270.43 kJ/mol, α=0.020 94, A=1.747×1011 s−1 and n=3.549 mm2·N−1, the deformation mechanisms of the alloy are self-diffusion and dynamic recovery.
Principle of multilayer spray forming and preparation technique of tubes and billets by it were presented and described in the article. The marked characteristic of multilayer spray forming technology is the to-and-fro movement of spray system, so the preform is deposited layer by layer with the surface of the deposit retaining relatively low temperature during the spray forming process. The two outstanding advantages of multilayer spray forming are as follows: suitable for manufacturing large dimension blanks, higher solidification cooling rate. Now Al-Fe-V-Si alloy (8009) and SiC particle reinforced aluminium alloy metal matrix composite billets of 300–600 mm in diameter and tubular blanks of size up to 650 mm in outer diameter, 360 mm in inner diameter and 1 200 mm in length have been made with the technology. After extrusion, the material has good properties.
Based on the experimental data by a full scale test model and the relevant existing achievements, four new concepts of group dust scrubbers were designed in the paper. The new dust scrubbers consist of two to four common dust separators in series: wet-fan, wet-Venturi and foam filter bed. Wetting and foaming agents are used to increase the efficiency of dust separation. High efficiency is not required for each part of the group dust scrubbers, but the whole system has a high working reliability. All parts of the group dust scrubbers have the most suitable separating efficiency for different size and concentration of dust particles in airflow, according to their technical features. Four group dust scrubbers have a high efficiency from 94.4% to 99.7% for separating respirable dust at a rational cost.
In Xikuangshan antimony ore-field, the western fracture zone is a composite of major fault, F75, and its secondary faults, such as F71, F72 and F3 etc.. On plane, the fracture zone scatters from southwest to northeast, and concentrates from upper to deeper level on profile. All ore-bodies exist in the carbonate of footwall of the major fault or that of the footwall of its secondary faults. From 480 m and 320 m to 120 m level, the fractal dimensional number of the fault system decreases from 1.482 2 and 1.448 6 to 1.339 2, which indicates the form of fracture zone becoming more simple at deeper level. And in five sub-ranges, the III and IV sub-ranges are the known area, and the I, II and V sub-ranges are unknown. The fractal studies of the western fracture zone in these sub-ranges show that the fractal dimensional numbers of the I and II, being 1.201 5 and 1.278 0, respectively, are smaller than that of the III and IV, being 1.475 9 and 1.576 9, respectively; and that of the V, being 1.571 2, keeps with that of the III, IV sub-ranges. So mineralization is not well in I and II sub-ranges, and V sub-range is the best to benefit mineralization.
Single phases of ammonium penta- and tetra- molybdates were prepared. The massic heat capacities at normal pressure below their decomposition temperatures were measured by drop method. The relationships of the massic heat capacities of ammonium molybdates with those of the decomposition products were also discussed. The results show that the massic heat capacities of ammonium molybdates can be estimated by adding together contributions from their decomposition products, and the less change of chemical bonds, the more accurate of the estimation.
The surfactant additive octadecylamine (ODA) was used to enhance the flow boiling heat transfer of water in vertical copper tube, and the effects of the aqueous solution properties, mass fraction of ODA, mass flux and heat flux etc. on flow boiling heat transfer were investigated. In order to analyze the mechanism of enhancement on boiling heat transfer with ODA, the copper surface was detected by XPS, and the diagram of binding energy was obtained. The results show that ODA can be adsorbed on the surface of the copper wall, and affects the properties of the heating surfaces and enhances the flow boiling heat transfer of water. Only in low heat flux and in a suitable range of concentration, can ODA aqueous solution enhance flow boiling heat transfer, and the suitable mass fraction of ODA is in the range of 1 × 10−5 −5 × 10−5. In addition, compared with water, ODA aqueous solution does not increase the flow drag under the same experimental conditions.