Enrichment of low concentrated nickel solutions by Dowex M4195 chelating resin

The main point of this study named as "Enrichment of Low Concentrated Nickel Solutions by Dowex M4195 Chelating Resin" enrichment of low concentration nickel-containing leaching solutions via ion exchange process. In this study, the absorption properties of Dowex M4195 chelating resin is investigated under different processes parameters with using synthetically leach solutions. In the first phase of study; effect of different resin/solution ratio, pH, and temperature are investigated. In the absorption experiments 1000 ppm Ni2+ solution was used. First of all, experimental studies start with different resin/solution ratio between 15 to 30 g/L. The maximum absorption yield is obtained from solution containing 30 g/L of resin. At the end of 24 hours, 92.68% of Ni2+ ions is absorbed from solution containing 30 g/L resin. All of the subsequent work is done with 30 g/L of resin addition. The effect of pH on absorption is investigated in the second stage of the absorption experiments. It has been determined that nickel absorption is limited when the pH is lowered as a result of the experiment for 6 hours at pH 0.8-0.4 At pH 0.8, the absorption rate was determined as 16.0%, 83.9% at pH 2, 85.3% at pH 3 and 85.9% at pH 4. Considering that the solution obtained after leaching would remain at acidic pH, the working conditions were fixed as pH = 2 and continued. In studies where the effect of temperature on the absorption examined, it is seen that as the temperature increases, the absorption rate increases and the amount of absorbed metal ions increases. However, because of the organic structure of the resins, they can be used at a maximum temperature of 65°C. In the experiment performed at room temperature, the absorption yield was 83.03%; 83.53% at 40°C and 87.27% at 55°C. The experimental results obtained at different temperatures were examined using the Brykina method and the activation energy of absorption was found to be 10.85 kJ / mol. Studies in the literature It is emphasized that Ni2 + ions absorbed on Dowex M4195 IXR can be stripped with 100 g / L H2SO4. This value corresponds to approximately 1M H2SO4 solution. If 1 M H2SO4 solution was used and the resin to solution ratio was 300 g/L, the Ni2+ solution was obtained at a concentration of 7150 ppm with an efficiency of 78.55%. Decreasing the ratio of the resin solution increases the efficiency of the elution, but the Ni2+ content of the eluate is reduced. As a result, 78.55% elution yield was obtained by using 300 g/L resin to solution ratio. It has been found that the H2SO4 concentration for the effective elution process should be 1M as a result of the elution procedures carried out at different H2SO4 concentrations using resin to solution ratio of 300 g/L. The Ni2+ concentration in the eluate is also dramatically decreased due to decreasing concentration of H2SO4. Considering that the leaching solution contains Ni2+ in a ratio of 1/10 of the synthetic solution used in previous experiments; two different resin to solution ratios of 3 g/L and 30 g/L were used in the absorption process using the leach solution. The low concentration of 3 g/L resin to solution ratio greatly influences the absorption rate in the experiment. However, absorption in the experiment using 30 g/L resin to solution ratio continues further. When resin concentration is 3 g/L, 72.0% and 90.3% absorption yield was obtained for resin to solution ratio of 3 g/L and 30 g/L at the end of 5 hours. Nickel leaching solution was subjected to absorption using 30 g/L resin to solution ratio. After that loaded resins were subjected to elution at a different acid concentrations using a resin to solution ratio of 300 g/L as an enrichment factor 10. Increased acid concentration increases the yield of Ni2 + elution and thus the eluate Ni2+ content. In the case where the eluate Ni2+ concentration is desired to be further increased, two different path can be used. The first method is to increase the enrichment factor by reducing the resin to solution ratio used in the absorption. The second method is to use the resins repeatedly in different solutions. Both methods, however, will lead to an increase in the absorption time.