[en] DP-8R and LIX 860 extractants diluted with Exxsol D100 was used to co-extract cobalt and nickel from sulphate aqueous media. The influence of equilibration time, temperature, equilibrium pH and extractants mixture concentration on the extraction of both metals has been studied. It was observed that neither cobalt nor nickel extraction is sensitive to temperature, reaching in both cases the extraction equilibrium within 5 min of contact however nickel is extracted preferably to cobalt at slightly acidic pH values and also using various extractants mixture concentrations. For a solution containing 2 g/l each of cobalt and nickel and initial pH value of 5,5 conditions were established for the co-extraction of both metals and selective stripping (with H₂SO₄) of cobalt and nickel. Using the appropriate extractants concentrations the yield (extraction stage) for both metals is near 90% whereas the percentage of cobalt and nickel stripping is almost also quantitative. (Author) 15 refs

[en] A great quantity of industries are responsible for contaminating the environment with the heavy metals which are containing in their wastewaters. The recovery of these metals is both from an environmental and economical points of view of the upmost interest. A study is made of the use of mill scale-originating in the hot rolling of steel-as an adsorbent for the removal of heavy metals from liquid effluents. The adsorption of Zn''2⁺, Cd''2⁺ y Pb''2⁺ on the rolling mill scale was investigated by determination of adsorption isotherms. The effect of time, equilibrium temperature and concentration of metal solution on mill scale adsorption efficiency was evaluated. The adsorption process was analysed using the theories of Langmuir and Freundlich. Desorption process of metals from loaded mill scales was also studied using several doser bent at different experimental conditions. It has been proved that the mill scale is an effective adsorbent for the cations studies in aqueous solutions within the range of the working concentrations. (Author) 32 refs

[en] In the Cuban Metallurgical Research Center (CIME), are manufactured by powder metallurgy, shims of adjustment of a W-Cu composite material, that are used in the electrical contacts of the panels of control of the portico derricks that operate in the port of Havana City. The base material used has a composition of 70% in mass electrolytic copper powder and wolfram powder of (30%) that is obtained by reduction from the oxide from wolfram. The powders are submitted to the stages of mixed, pressed and agglomeration and is obtained a composite material with free particles of W occluded in a counterfoil of Cu matrix, that do not interact and they provide the following properties: high melting temperature, high electro and thermo conductivity and corrosion resistance, high mechanical and electrical strengtheners, decrease weldability and stability during their development. However, when not reacting the volframio particles with the copper, the compound material will begin to fuse to the temperature of the copper, on the other hand and for the same reason the resistance to the corrosion should be similar to that of the pure copper. The shims of adjustment are fixed to the bodies of high purity copper welding with a silver alloy, the one which provides the maximum qualities of the Cu, as elasticity, breaking strength, thermal and electrical conductivities, as well corrosion resistance. (Author) 36 refs