Method and device for zinc electrowinning from sulfate solutions

Abstract

The invention relates to a method and a device for electrowinning of zinc from sulfate solutions. The electrolyzer for zinc extraction according to the invention includes a bath-reactor which is equipped with power supply buses, a pipeline of two pipes for supplying the electrolyte, cathodes, anodes, plastic strips along the height of the anodes, an overflow for electrolyte discharge by gravity. The cathodes have an area of 3.5-10 m 2 . The height of the electrolyzer is at least two times greater than its width, and the length of the electrolyzer depends on the number of the electrodes. The bottom of the electrolyzer is divided by a groove along the length of the bath.

1 . An electrolyzer for zinc electrowinning, characterized in that it includes a bath-reactor ( 5 ), equipped with power supplying buses ( 6 ), a pipeline of two pipes ( 1 ) for feeding the electrolyte, cathodes ( 3 ), anodes ( 4 ), plastic strips ( 8 ) along the height of the anodes ( 4 ), an overflow ( 2 ) for electrolyte exit by gravity, where the cathodes ( 3 ) have an area of 3.5-10 m 2  and the height of the electrolyzer is at least two times greater than its width. The length of the electrolyzer depends on the number of the electrodes, and the bottom of the electrolyzer is divided by a groove ( 11 ) along the length of the bath ( 5 ). 
     
     
         2 . An electrolyzer according to  claim 1 , characterized in that the anodes ( 4 ) are made of pure lead, alloyed with 0.3 to 1.0% Ag. 
     
     
         3 . An electrolyzer according to  claim 1 , characterized in that the height of each anode ( 4 ) is divided into two equal parts and their total effective area is greater than that of the cathode ( 3 ), and the thickness of the anode ( 4 ) is 12-18 mm. 
     
     
         4 . An electrolyzer according  claim 1 , characterized in that power feeding buses ( 6 ) are made of copper and there is a copper bar ( 7 ) fixed on them. 
     
     
         5 . An electrolyzer according  claim 1 , characterized in that the plastic strips ( 8 ) are installed so as to cover the edges of anode ( 4 ) to at least 80% of the height and in the middle and the lower part the anodes are fixed by a plastic disc washer ( 10 ) between anode ( 4 ) and cathode ( 3 ). 
     
     
         6 . An electrolyzer for zinc electrowinning, characterized in that it consists of two connected electrolyzers according to  claim 1 , where between the two baths is provided a siphon-overflow ( 9 ) for the solution, leaving the first bath by gravity and entering the second bath from the bottom to the top. 
     
     
         7 . A method for zinc electrowinning with a device according to  claim 1 , characterized in that it consists of:
 feeding process electrolyte solution, containing zinc, sulfuric acid ˜120-200 g/l and additives as an option at the temperatures of 25-32° C. at the inlet and 36-38° C. at the outlet, and pressure 1.5-2 atm., through a pipeline ( 1 ) into the bath-reactor ( 5 ) and electric power by means of the buses ( 6 );   electrolysis at the current density of 250-500 A/m 2 , maintaining electrolytic solution circulation speed of 1.5÷3 bath volumes per hour, where the anode-to-anode distance is ˜80-86 mm and the duration of the cathode cycle is 72 hours (48-96 hours), and the temperature of the electrolyte at the exit is 36-38° C.   
     
     
         8 . A method according to  claim 7 , characterized in that the process electrolytic solution contains 120-200 g/l sulfuric acid.