Cüneyt Arslan

Recovery of copper, cobalt, and zinc from copper smelter and converter slags

A study on the recovery of copper, cobalt, and zinc from copper smelter and converter slags by roasting with sulfuric acid has been conducted. Acid roasting of slags followed by hot water leaching was carried out to bring the metal values into solution. In the leaching experiments, the effects of roasting time, acid/slag ratio, roasting temperature, and application of thermal decomposition prior to leaching on the metals dissolution extents were investigated. A total of 88% of copper, 87% of cobalt, 93% of zinc, and 83% of iron were extracted in 2 h of roasting at 150 °C and 3:1 acid/slag ratio. Increasing acid roasting temperature and time did not have increasing effect on the Co and Zn dissolution extents, while significant improvements were observed in Cu dissolution. Application of thermal decomposition prior to leaching gave small decreases in metal extractions, but since there was no iron dissolution, it was favoured from the viewpoint of metal recoveries from the leachates due to the elimination of an iron removal step.

Nickel recovery from the rinse waters of plating baths

Abstract An electrolytic process is applied to the de-metalization of rinse waters emerging from nickel-plating baths. Optimum conditions of nickel recovery from this type of solution have been investigated through a series of experiments carried out in a rotating packed cell (Rollschichtzelle®). The effects of temperature and pH of electrolyte, current density, cell rotation speed, and diameter of the cathode granules were examined. Ninety percent of the nickel was recovered from a solution of 450 mL volume, with a pH of 5.5±0.05, 2 g/L initial nickel concentration, and by using cathode granules of 5 mm in diameter. At 50 °C electrolyte temperature and 325 A/m2 current density, 74% current efficiency was attained with 4.2 kWh/kg Ni energy consumption.

Arsenic removal through the decrepitation of colemanite ores

Abstract Despite their high boron contents, some boron deposits in Turkiye contain considerable amountS of arsenic. Arsenic in boron minerals receives penalty in marketing and thus its removal is necessary. Since colemanite undergoes decrepitation at temperatures near its decomposition, the objective of this study was to determine the extent of arsenic removal through the decrepitation of colemanite ores with high As content. The effect of temperature, retention time, and particle size range was investigated and the degree of arsenic removal and the quality of colemanite concentrate were quantified. The results reveal that arsenic removals of 95–98% with As levels as low as 0.02% in the colemanite concentrate are achieved.

Kinetics of copper precipitation by H2S from sulfate solutions

The kinetics of copper precipitation by H2S from sulfate solutions were investigated by bubbling the gas through an aqueous solution. It was observed that the rate of precipitation increases as the solution pH increases. It was shown that the reaction rates and mass transfer coefficients were increased by either increasing the gas flow rates with constant bubble diameter or by decreasing the bubble diameter at constant gas flow rates. This was due to the increased interfacial area between the gas and liquid phases. The average diffusion coefficient of H2S was calculated from the experimental data and was found to be 1.987·10−9 m2s−1, which is very close to that in water (1.61 · 10−9 m2s−1).

Beneficiation of brass ashes

Abstract Slags formed during brass smelting contain a significant amount of metallic value. The glassy and oxidized portion of the ground slag, usually referred to as “brass ash”, consists of compounds such as ZnO, ZnO·SiO 2 , Cu-Zn, CuO, Cu and Zn/Cu/B oxide, and its colored-metal content may vary between 28÷52% Zn and 8÷16% Cu. These ashes are classified as harmful wastes, due to their high Zn content, and are considered to be secondary raw materials that should be treated accordingly, from an economical viewpoint. The aim of this experimental study is to investigate the possibilities of beneficiating brass ashes by treating it with H 2 SO 4 or (NH 4 ) 2 CO 3 + NH 4 OH mixtures. Effects of temperature, air sparging and addition of oxidizing agents, such as MnO 2 and Fe 2 (SO 4 ) 3 , are investigated on copper and zinc leaching recovery. As a result of both acidic and alkaline leaching experiments, it is observed that more than 90% of Zn and more than 65% of Cu was leached out. Two separate process flow sheets are proposed for the possible treatment of brass ashes.

Roasting of Celestite in Laboratory Scale Rotary Furnace

Turkish celestite ore was roasted in a lab scale rotary kiln furnace with metallurgical coke. Coke and celestite were mixed; the product contained 32% coke which is more than the stoichiometric requirement. 100 g of the mixed product was fed to a rotary furnace at 35 g/min. Temperature (1000 and 1100 °C), rotation speed (2.5, 5 and 10 rpm) and the slope of the furnace (2, 3 and 5°) were among the investigated parameters. Phase and chemical analyses were carried out by XRD and XRF techniques, respectively. The maximum solubility of the roasted product in water was 48% under the roasting conditions of 1100 °C, 2.5 rpm and 2° slope.

Direct Conversion of Celestite to SrCO3 by Wet Milling

Effect of the high energy ball milling on the direct conversion of celestite to strontium carbonate (SrCO3) was studied. Celestite ore was ground by a planetary ball mill with sodium carbonate (Na2CO3) solution. Experimental study carried out to determine the effects of milling time (5, 10, 15, 30, 60, and 120 min) and Na2CO3 concentration (1, 1.25, 1.5, and 2 M) on the precipitation efficiency. Volume of carbonate solution was calculated for the stoichiometric amount of sulfate in celestite and solid material/ball weight ratio is selected 1/10 as constant. After filtering, washing and drying the precipitated SrCO3 sludge was analyzed by X-Ray Diffractometer (XRD), Scanning Electron Microscope (SEM), and Energy Dispersive Spectroscopy (EDS). The conversion rate of celestite to SrCO3 increased systematically with extending milling time. The strontium carbonate in the product can be concentrated up to 99.8% by 120 min wet milling of celestite in 2 M Na2CO3 solution.

Production of Strontianite from Celestite Ore in Carbonate Media

Celestite ore (SrSO4) is used as raw material for the production of strontium compounds. The aim of this study is to develop a new and efficient strontianite (SrCO3) production method. Strontianite was obtained from domestic celestite concentrate with direct conversion method in which celestite reacts with \( {{\text{CO}}_{3}}^{2 - } \) and \( {{\text{NH}}_{4}}^{ + } \) containing solution. Thus, the effect of particle size, time, ammonia concentration on the conversion was investigated. \( ({\text{NH}}_{4} )_{2} {\text{CO}}_{3} \) solution was used as carbonate agent. Because the solution is decomposed at 58 °C, experiments were performed low temperatures. Celestite ore was converted to strontianite between 3 and 6 h depending on ammonia concentration and celestite mass. Characterization of celestite ore, products and reaction residues were carried out by DSC, TG, XRD, and AAS analytical techniques.

Investigating the Dissolution Characteristics of Strontium Sulfide

Celestite is the main source of strontium containing chemicals and metallic strontium. Unlike other sulfate containing minerals, celestite is not soluble in water. Further processing of SrSO4 requires conversion to water-soluble strontium sulfide (SrS). In this study, solubility of SrS in distilled water is investigated. SrS used in experimental study was obtained by roasting celestite at 1050 °C in a lab-scale rotary furnace. Experiments were carried out to determine the effects of time (90, 120, and 150 min), solid/liquid (S/L) ratio (1/5, 1/10, and 1/25 w/v) and temperature (25, 55, 75, and 95 °C). Stirring speed (500 rpm) was constant. XRD results of leach cakes showed that increasing temperature increases dissolution rate and efficiency. However, increasing S/L ratio decreases the leaching efficiency.