Patent GB-832072-A (GB)
Title: Process and equipment for obtaining mineral and chemical products by means of hydrometallurgy
IPC: C22B3/04
Filed: 1956-10-05
Abstract: 832,072. Lixiviating; treating solids with liquids. MORENO, F. L. Oct. 5, 1956 [Oct. 5, 1955], No. 30510/56. Class 82(1) In a process and apparatus for obtaining mineral and chemical products by accelerated hydrometalling the extraction of a desired product in a solid is carried out by placing it suitably crushed in a vessel 2 (Fig. 4) with a filter bed 3 and keeping it static while circulating through the particles of solid in an ascending and/or descending sense in a closed circuit a solvent of which the volume used is that of the interstices between the particles, representing substantially 40% of the total volume of the crushed solid. The filter bed 3 preferably forms a hermetic seal with the walls and is on top of a closed chamber of the same cross-section as the vessel is internally and below it the bottom slanting slightly towards the outlet 4 for the solvent into an intermediate container 5 of the same height as the vessel and in which the solvent rises until it reaches the same level as in the vessel. A pump 6 or pumps may be used to raise the solvent to its level in the container 5 and then over the vessel 2 to fall on the crushed solid, the cycle being repeated until the desired product is completely dissolved. Where the particles are of different sizes the finer particles can be placed in a vessel 8 (Fig. 7) open at the bottom and resting on the filter bed, so as to automatically distribute the stream of solvent pumped in at the top, excess overflowing into the largersized particles in an enclosing vessel which absorbs more solvent. With extremely fine particles the cycle of solvent should be passed upwardly so that the walls 9 (Fig. 8) have a canal 10 along the top (the bed of the vessel being inclined), from which the solvent discharges by tubes 11 and 12 to the top of the intermediate container closed by a hermetically-sealed plate 13. When the process is used to extract copper from a mineral such as sulphate, the solution finally obtained is passed through a Dorr type of settler and overflows through connections to a vessel or vessels 18 (Fig. 10) acting as a deposit regulator for the solution and is pumped at 19 into distributing ducts 20 so that jets descend on to scrap iron as a fixed cathode to give on compact a deposit of copper between 90 and 99.7% in purity, the solution returning through tubes 21, 22 and 23 to the vessel(s) 18 to continue the circulation. The use of fixed cathodes of scrap iron for rotary cathodes produces a potential difference which furthers the depolarization thereof by acting as a diaphragm to prevent the deposit of noxious elements such as ferric sulphate to give a more compact deposit of copper, by throwing the solution over the iron at a linear speed per unit of time similar to the tangential speed produced by a rotary cathode because of the pumps and the height the jets drop, which due to friction with air acquire an electrostatic charge of contrary polarity to the iron. Scrap iron 24 is located in a position normal to the jets 27 beneath a duct, a piece 25 when immersed (Fig. 11) having a low yield, contrary to the deposit on the piece 24. Gold could be similarly obtained from gold-bearing, material by using sodium cyanide and an air aspirator for oxygen, zinc shavings being used for preciptation.