AU595949B2 - Electric conductor for metal salt electrolytic cell - Google Patents

Description

1 19 COM MON W EA LT H 0F, A UST RA LI A PATENT ACT 1952 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE CLASS INT. CLASS Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority:- Related Art-: ff S 49 This doc u et1t contain C tl(j made Und tion 4 9 arnbd s correct f J)Iin ting. 0 r 00 0 0 00 0 04 0004 0000 0 40 0 0 0 0 00 0000 o 0 0004 00 0 0 0 0 Re NAME OF APPLICANT: ADDRESS OF APPLICANT: MITSUI MINING SMELTING CO.. LTD.

00 0 a 0 040 0 04 0 0 0 Ro 1-1, Nihonbashi Chuo-ku, Tokyo, Muroniachi 2 -chiorne,

JAPAN.

040400 o 000005 0 0 A 09 00 0*4 8 NAME(S) OF INVENTOR(S) Takashi ISHII, Tsugio SHOUTA, ADDRESS FOR SERVICE: DAVIES COLLISON, Patent Attorneys 1 Little Collins Street, Melbourne, 3000.

COMPLETE SPECIFICATION FOR TEB INVENTION ENTITLED: "ELECTRIC CONDUCTOR FOR METAL SALT ELECTROLYTIC CEL~L" The following statement is a full description of this invention, including the best method of performing it known to us I- f To: THE COMMISSIONER OF PATENTS (a member of the firm of DAVIES COLLISON for and on behalf of the Applicant).

Davies Collison, Melbourne and Canberra.

SPECIFICATION

Title of the Invention Electric conductor for metal salt electrolytic cell Background of the Invention This invention relates to an improvement of an electric conductor (busbar) to be disposed in an electrolytic cell in order to supply electricity to electrodes in the metal salt electrolytic cell.

eQob In electrolysis of a metal salt aqueous solution in a op general, there are used a variety of methods to reduce the 00a e eo contact resistance, and fluctuation thereof, of contacts between electric conductors disposed on side walls of an electrolytic cell and anodes and cathodes which are in contact with the electric conductors. For example, 4 eanese P~.-At 1' 1/ E7. discloses an electric a a S conductor in which the contact is damped with an a t electroconductive liquid to reduce the contact resistance and fluctuation thereof even in an electrolysis for an extended period of time. In the electric conductor, referring to Figs.l and 2 showing an example of electrolytic refining of copper, an electric conductor 1 has a liquid containing member 2 and an impregnatable member 3 such as sponge placed in the liquid containing member 2, an of the application, Insert place and date of signature. Declared at Tokyo, Japan this 20th day o ctober, 1987 Signature of declarant(s) (no attestation required) Mitsui Mining Smelting Co.,Ltd.

Note: Initial all alterations. Representative Kozabu Majima DAVIES COLLISON, MELBOURNE and CANBERRA.

U 1 electrode or electrode beam 4 (cross bar or shoulder) is supported through the liquid containing member 3, and the liquid containing member 2 is continuously dropped, or intermittently supplied, with an electroconductive liquid so that the impregnatable member 3 is always damped at its contact with the electrode 4. City water or industrial water (underground water) is used as the electroconductive liquid.

However, such a prior art electric conductor has been 0 0 defective in that there occurs a deposition cn the electric conductor, but the deposition cannot be removed by spraying a 0* *9a sulfuric acid which is normally carried out for cleaning S oxide films. Therefore, in addition to replacement of the impregnatable member 3 to be impregnated with the S, electroconductive liquid when it is deteriorated, there has Sat been required polishing to remove the deposition from the electric conductor.

With a view to obviate all of the prior art defects of electric conductor, it is a primary object of the present invention to provide an electric conductor for use in a metal salt electrolytic cell, which is prevented from occurrence of a deposition.

Summary of the Invention The inventors of the present invention have conducted 2 intensive investigation for solving the above described prior art problems and found that the deposition occurring in the electric conductor consists mainly of calcium sulfate resulting from the reaction of Ca in the electroconductive liquid, which is evaporated and concentrated by ohmic heat of electric current passing through the electric conductor, with sulfuric acid in scattered electrolyte or in dilute sulfuric acid used for cleaning which remains unremoved 0 after washing with water.

In accordance with the present invention, based on the 0 00 0* above findings, which attains the above object, there is 0, provided an electric conductor for use in a metal salt soLc S-eLcsjc cj S\eC.- C-.

o electrolytic cel SeImed in contact with electrodes r electrode beams through an electrocoAductive liquid and>±aAd o at in a metal salt electrolytic cell using a metal sulfate as S' an electrolyte or using a liquid containing sulfuric acid as a cleaning solution, which is characterized in that the electroconductive liquid tr he .supplied -i th -cr 4: .a-.duator- has a calcium concentration of 1 mg/liter or less.

The electric conductor according to the present invention provides reduced amounts of deposition, with considerably reduced number of polishing operations required for the removal of the deposition since the deposition consists mainly of copper sulfate which is easily soluble in dilute sulfuric acid. This results in a reduced contact

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r 3 -v~ i 4 1 o« resistance between the electric conductor and electrodes, with reduced fluctuation of the contact resistance.

Brief Description of the Drawings Fig.1 is a schematic view showing an electric conductor which is used in contact with electrodes or electrode beams through an electroconductive liquid. Fig.2 is a schematic sectional view of the electric conductor.

Detailed Description of the Invention The present invention will now be described further in *O detail with reference to an embodiment.

The same electric conductor as shown in Fig.1 and Fig.2 was installed in a copper electrolytic cell of 1.2 m in width, 4.85 m in length, and 1.35 m in height of a copper refinery, and supplied with water at a rate of 15 m 3 /day which was based on city water, softened to 2 us/cm by passing 0 Oc (t r e- 6z L K S through a water softener, bOrgano oe. L~ The softened water had a Ca content of 1 mg/liter or less. A sponge of o mm in width and 1,500 mm in length was used as an impregnatable member.

In this embodiment, using the softened water, the electric conductor provided stable operation over a long period of time by conventional periodic washing with dilute sulfuric acid and then with water. Therefore it was 4 0* -4- \0 A -w 'sC^ 1 sufficient to remove deposition by polishing only once a year. Average composition of the removed deposition is shown in Table 1.

A comparative example which used untreated city water as an electroconductive liquid in the same electrolytic system required polishing removal of deposition at a rate of once every three months. The Ca content of the city water supplied was 19 mg/liter. The composition of the deposition is shown in Table 1.

Table 1 S* Embodiment Comparative Po. Ca 2.3 19.3 S 6.6 15.8 I Vo Cu 23.0 0.6 Na 0.97 0.4 It can be estimated from Table 1 that the small amount e of deposition generated in the embodiment is based mainly on S copper sulfate, which agrees well with the fact that the o o deposition can be cleaned using dilute sulfuric acid.

p O In the above-described embodiment, the decrease in amount of the deposition provided a reduction in contact resistance, corresponding to a 3 mV decrease in voltage compared to that for the comparative example, thereby accomplishing a reduction in original unit of power of 3 KWH/T of electrolytic copper.

Thus, the amount of deposition can be considerably 0 0 reduced by using an electroconductive liquid to be supplied into the electric conductor, which has a Ca content of 1 mg/liter or less, preferably 0.1 mg/liter or less. When a solution is used as an electroconductive liquid, water as a solvent for the solution should also be softened as Cescribed above.

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Claims (1)

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