US2602775A

US2602775A - Electrodeposition of zinc

Info

Publication number: US2602775A
Application number: US186323A
Authority: US
Inventors: Isherwood Eldon Irwin
Original assignee: Hudson Bay Mining and Smelting Co Ltd
Current assignee: Hudson Bay Mining and Smelting Co Ltd
Priority date: 1950-08-10
Filing date: 1950-09-22
Publication date: 1952-07-08
Anticipated expiration: 1969-07-08
Also published as: GB693538A; DE880214C; BE504924A

Description

latented July 8, 1952 I'M-UNITED 2,602,775 7 ELEo'rRonEPosi'rIoNengine Eldon is'nerwood, FlinajlulilQMiritoba, Canada, assign'or to Hudson; Bay Mining and 'Smelting 00., Limited,

. Canada, a corporation oilfiariaida.

nipeg, Manitoba,

No Drawing Application .septofiiber 22, 1950, Serial No. 186,323. In Canada August 10,119.50

6 Claims. 1

This invention relates to the electrodeposition of zinc from zinc sulphate solutions using lead base alloy anodes. By lead base alloy anodes is meant anodes formed of an alloy consisting chiefly of lead.

As is well known, it is desirable in the electrodeposition of zinc from zinc sulphate solutions to use anodes consisting of lead or consisting chiefly of that metal, and indeed it is generally considered that such anodes are the only ones suitable. Such anodes are, however, subject to the disadvantage that, during the operation of the electrolytic cell, some of the lead from the anode is transferred to the cathode zinc deposit, thereby contaminating it, and decreasing the value of the zinc produced. For certain purposes, such as pressure die casting, it is essential that zinc be almost free from certain impurities, one of the most objectionable of which is lead.

Many attempts have been made to decrease this lead transfer from'anode to cathode and various lead base alloys have been proposed for use as anode material. Some of these lead base alloys have been partially successful, the most popular lead base alloy anode in use at present in the electrolytic zinc industry consisting of lead and a small amount of silver varying up to about 2.0% by weight. Other investigators have found that the addition of tin or tin and cobalt to this basic lead-silver alloy gives good results.

It has now been found that the use of a lead base alloy anode containing small amounts of copper as well as small amounts of silver, has a very pronounced and surprising effect in reducing the transfer of lead from anode to cathode. Actual tests have shown a reduction in the amount of lead found in the cathode zinc of as much as about two-thirds when a lead base alloy anode containing small amounts of copper as well as small amounts of silver is used in place of the usual lead base alloy anode, consisting of lead and silver. It has also been found that there is an even greater improvement over lead-silver anodes when there is used a lead base alloy anode, consisting of lead and small amounts of silver, copper, cobalt and manganese.

Thus, according to the invention, zinc is deposited from a zinc sulphate solution with an alloy anode consisting essentially of lead alloyed with small amounts of silver and copper, the percentage of silver being advantageously within the range of about 0.3% to about 1.45%, and of copper being about 0.1% to about 0.4%. It has been found that the best results are obtained with such an alloy anode containing about 1% silver, about 0.25% copper and the balance lead.

According to the invention, the electrodeposition of zinc from a zinc sulphate solution may also be carried out to advantage with a lead base alloy anode consisting essentially of lead alloyed with small amounts of silver, copper, cobalt and manganese, the percentages falling within the ranges of from about 0.4% to about 1.45% silver, from about 0.15% to about 0.45% copper, from about 0.01% to about 0.02% cobalt and from about 0.01% to about 0.15% manganese. It has been found that the best proportions for an alloy anode of this composition are about 1.0% silver, about 0.5% copper, about 0.02% cobalt, and about 0.1% manganese.

The effect of carrying out the electrodeposition with the lead-silver-copper and lead-silver-copper-cobalt-manganese alloy anodes in reducing the transfer of lead from anode to cathode, as compared with a lead-silver anode, is illustrated by the following table showing the results of laboratory tests. The percentages given are by weight and, in each case, the remainder of the anode is lead.

Assays of Anodes Percentage A r of li N ssay o opera on Test 3.5%; Cathode with lead I\ o. of Test Ag Cu 00 Mn Zn Pb in cathode Per Per Per Per Per Cent zinc Cent Cent Cent Cent 0.0010% or less.

l. 0 Nil Nil Nil 0. 0038 2 78 0. 28 0. l2 Nil Nil 0. 0022 12 78 0. 96 0. 25 Nil Nil 0.0015 46 78 1. l2 0. 21 Nil Nil 0. 0013 48 78 1. 45 0. 40 Nil Nil 0. 0014 40 78 0. 36 0. l5 01 01 0. 0020 19 7 78 0.75 0.20 01 06 0. 0014 31 8 78 1.03 0.35 01 0. 11 0.0012 63 9 78 1. 45 0.45 01 0. 14 0.0011 57 10 84 0.98 0.75 02 06 0. 0012 79 11 84 0. 47 0.32 .01 .02 0. 0010 63 What I claim as my invention is 1. A process for the electrodeposition of zinc from a zinc sulphate solution, which comprises causing deposition of zinc from the solution with an alloy anode consisting essentially of lead alloyed with small amounts of silver and copper.

2. A process for the electrodeposition of zinc from a zinc sulphate solution, which comprises causing deposition of zinc from the solution with an alloy anode consisting essentially of lead alloyed with small amounts of silver, copper, cobalt and manganese.

3. A process for the electrodeposition of zinc from a zinc sulphate solution as defined in claim 3 1, in which the amounts or silver and copper respectively present in the alloy anode are within the ranges of from about 0.3% to about 1.4% silver and from about 0.1% to about 0.4% copper.

4. A process for the electrodeposition of zinc from a zinc sulphate solution as defined in claim 3, in which the amount of silver present in the alloy anode is about 1.0% and of copper is about 0.25%.

5. A process for the electrodeposition of zinc from a zinc sulphate solution as defined in claim 2, in which the amounts of silver, copper, cobalt and manganese respectively present in the alloy anode are within the ranges of from about 0.4% to about 1.45% silver, from about 0.15% to about 0.45% copper, from about 0.01% to about 0.15% manganese, and from about 0.01% to about 0.02% cobalt.

5 0.5%, of cobalt is about 0.02% and of manganese is about 0.1%.

ELDON IRWIN ISHERWOOD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 15 Number Name Date 1,681,272 Yoshikawa Aug. 21, 1928 1,699,761 Silberstein Jan. 22, 1929 2,419,722 Lowe et al Apr. 29, 1947

Claims

1. A PROCESS FOR THE ELECTRODEPOSITION OF ZINC FROM A ZINC SULPHATE SOLUTION, WHICH COMPRISES CAUSING DEPOSITION OF ZINC FROM THE SOLUTION WITH AN ALLOY ANODE CONSISTING ESSENTIALLY OF LEAD ALLOYED WITH SMALL AMOUNTS OF SILVER AND COPPER.