FI72151B - ELECTRICAL EQUIPMENT FOR ELECTRIC SHOCK ABSORBERS WITH NICKEL - Google Patents

Description

I.. «To-, t rDl / 44X ANNOUNCEMENT Π OAC η jr (W <11) UTLÄGGNINGSSKRIFT '^ ^' C (45) P- tc :: 11i iy '5n; cc ity (51) Kv.lk.4 /lnt,CI.4 C 25 C 1/08 FINLAND-FINLAND (21) Pttenttlhikemu * - Patentansfiknlng 750139 (22) Application cloud - Ansökningsdig 21.01.7 5 (FI) (23) Initial cloud - Glltlghetsdag 21.01. 7 5 (41) Become Public - Blivit offentllg 09.08.75

National Board of Patents and Registration of Finland Nihtiviksipenon | s kuui. - 31.12.86

Patent · och registerstyrelsen '' Amökan utlagd och utUkriften publkerad (86) Kv. application - Int. trap (32) (33) (31) Privilege requested - Begird priorItet 08.02.74

Canada (CA) 192114 (71) The International Nickel Company of Canada, Limited, Copper Cliff,

Ontario, Canada (CA) (72) Aubrey Stuart Gendron, Mississauga, Ontario,

Victor Alexander Ettei, Mississauga, Ontario, Canada (CA) (74) Oy Kolster Ab (54) Method for electroprecipitation of substantially sulfur-free nickel -Förfarande för elektroutfä11 Ning av väsentliqen svavelfri nickel

The invention relates to the electronically recovering and refining of nickel. More particularly, the invention relates to a method of electrodeposition of a cathode material made of titanium, sulfuric acid-resistant titanium alloy, aluminum or stainless steel, adhering but removable, a substantially 2 nickel-free nickel layer having an internal stress of up to 1800 kp / cm and a strong. . .... 2 .. ...

at least 1 mm, for a uniform area of at least 1 dm from an aqueous electrolyte substantially free of chloride.

The invention is characterized in that the pH of the electrolyte is in the range of 1.5-5.5, the cathode material is protected at the edges and the maximum depth of the profile of the surfaces subjected to the treatment of the cathode material is in the range of 0.028-0.078 mm.

When recovering nickel from ores, residues and the like by extracting the ore or residue and precipitating nickel from the formed solution by means of electricity, extraction is often carried out using an aqueous solution of sulfuric acid. In particular, in order to avoid the difficulties caused by higher corrosion and higher tensile stress of nickel deposition, it is desirable to avoid the use of chloride ion in the system as much as possible. In addition, to obtain a pure nickel product, the electrolyte from which the electrodeposition is performed must be relatively free of sulfur dioxide, thiosulfate, and the like, which tend to precipitate sulfur simultaneously with the nickel and reduce the internal stress of the electroprecipitation.

72151

In addition, it is desirable to deposit nickel on permanent cathode plates or substrates. Such plates or substrates, which are usually flat plates of about one square meter in size, must be able to operate repeatedly with the lowest possible reprocessing costs, they must be able to attach relatively high positive internal stress, mostly sulfur-free electrodeposited nickel to a larger surface of at least one millimeter may cause high ohmic resistance between the support surface and the nickel deposit and the thick nickel deposit must be able to be easily and controlled removed from them after electrical deposition when an automatic removal device is used. For repeated reuse, they must withstand corrosion in the electrolyte even if no current is conducted and are therefore made of stainless steel or titanium, sulfuric acid-resistant titanium alloy or, preferably, due to their low cost, aluminum.

To date, it has reportedly not been possible to find a satisfactory solution on an industrial scale to the problem of obtaining a substantially sulfur-free nickel electric precipitate of at least 1 mm thick and at least one square decimetre on a permanent cathode plate of an aqueous nickel sulphate electrolyte substantially free of chloride, which have been set above for the proper operation of the reusable cathode plate.

This is mainly due to the fact that of all sulphate electrolytes, electrically precipitated nickel tends to peel off the surface of the permanent cathode plate due to the high positive internal stress of the precipitate or when deposited under lower stress conditions, adhering too tightly for easy removal without damaging the cathode plate.

The invention is based on the finding that the cathode plate is covered at its edges and its exposed surface is preferably roughened by sandblasting to roughness, the maximum profile height is 0.028-0.078 mm and if the electrolyte pH is in the range of 1.5 ~ 5.5 the internal stress of the electrodeposition can be correlated with a thickness and a maximum dimension such that the precipitate adheres to the cathode plate during electroprecipitation, but the finished precipitate can be easily removed therefrom, for example automatically,

The internal stress of substantially sulfur-free nickel precipitates (i.e., precipitates containing up to 0.00 ^ +% sulfur) obtained from sulfate-containing sulfate electrolytes without chloride ions can be controlled by changing the electrolyte temperature and pH. When the internal stress is positive, it decreases with increasing temperature from about 1800 kp / cm2 at U0 ° C to about 1100 kp / cm2 at 70 ° C and about 700 kp / cm2 at 85 ° C (all at pH 3.0 ) and increases with increasing pH.

The roughness of the cathode plate is important because the higher the roughness of the plate, the greater the adhesion of the metal to the plate. Against the adhesion caused by the roughness of the base plate and the specific adhesion of the electroprecipitated metal to a given 72151 substrate, the internal stress of the electroprecipitated metal acts on the distance of the neutral stress point or line. If nickel is deposited on a planar surface, the positive internal stress causes compressive forces that are in equilibrium in the center of the planar surface. This stress distribution causes the electrical deposit to detach, which begins at its outer circumference and causes the detached plate to concave. The larger the surface area of the plate, the greater the forces causing the plate to peel from the outer circumference. Also, the thicker the electrical deposition, the greater the forces causing the detachment.

If the roughness is less than 0.028 mm, the adhesion of the precipitate is unreliable, while a roughness greater than 0.078 mm is difficult to obtain in a controlled manner by sandblasting or some other rapid, inexpensive roughening method. Preferably, the roughness is between 0.030 and 0.075 mm. If the stress of the precipitate is too high or the size or thickness of the final precipitate is too large at a given stress level, the precipitate tends to peel off and fall off the cathode, shorting the anode or damaging the cathode bag. Correspondingly, too little stress at a given size and thickness in the precipitate causes the precipitate to adhere to the cathode so tightly that it is difficult to remove the finished precipitate.

The precipitate must be at least 1 mm thick, as thinner deposits are difficult to remove automatically and thicknesses in the range 1-6 mm are suitable.

The stress and roughness corresponding to a certain amount and thickness of the precipitate can be determined experimentally. As a guide, deposition of nickel up to a thickness of 6 mm in the area of 1 m, for example on a square meter standard cathode plate, gives a satisfactory combination between the adhesion of the precipitate and its removability when the internal stress of the precipitate is 500-1800 2 kp / cm.

The cathode plates used in the process of the invention are made of stainless steel, aluminum, titanium or sulfuric acid resistant, preferably titanium-rich titanium alloy. On a full industrial scale, each individual cathode plate that metal deposition is prevented on the edges and outer circumference of the cathode plate. The cathode plates are placed in the cells against the anodes so that metal simultaneously precipitates on both sides of the plate to equalize the stresses generated in the plate. As is common in the electrical refining of nickel, the cathode plates can be placed in the bags and the purified electrolyte is fed to the cathode compartment bounded by the bag to maintain a hydrostatic pressure from the catalyst. A bubbling gas stream, as disclosed in CA Patent Application 163,360, can be used in the catalyst compartment to mix the catalyst to use higher cathode current densities of 1+ 721 51 while maintaining cathodic precipitation quality.

The cathode plates are preferably made for use by sandblasting the surfaces of the plates.

Surface roughness in the desired range can be obtained by sandblasting No. 1 or 2 grade sand with an average particle size of 30 mesh (0.595 am) using a cabinet type sandblasting machine. It should be noted that the exact conditions in sandblasting depend on various factors, including the hardness of the sheet metal, the quality and size of the sand, and the average speed and angle at which the sand impinges on the metal. Other abrasive particles can be used, such as microspheres and alumina. Metal granules, such as iron shot and granules, should be avoided because a metal-contaminated surface of a cathode plate can cause changes in the electrochemical behavior of aluminum, titanium, or stainless steel and contaminate electrodeposited nickel.

The roughness mentioned in this brochure and in the claims is measured according to the maximum profile height, i. according to the normal pattern formed on the surface, measured from the deepest cavity to the peak of the highest elevation, as shown by Surface Preparation Specifications, Commercial Blast Cleaning, Number 6, SSPC-SP6-63, October 1, 1963.

The aqueous chloride-free electrolyte from which the nickel is precipitated suitably contains Uo-110 grams per liter (g / l) of nickel as sulphate, 100-200 g / l of sulphate ions and 5 ~ 50 g / l of boric acid. The electrolyte may further contain suitable amounts of substantially inert, conductive cations, such as sodium and magnesium, up to about 100 g / L to reduce ohmic resistance. The pH of the electrolyte is kept in the range 1> 5 ~ 5> 5 · When electronically recovering metal from this electrolyte, 5-30 g / l of nickel is usually removed from it, the removal being measured as the difference between the nickel concentrations of the electrolyte fed into the cell and the electrolyte removed from the cell. The temperature of the electric recovery cell is suitably maintained in the range of 50 to 95 ° C, and insoluble anode electrodes (e.g., a ruthenium oxide-coated titanium or lead alloy) are used as the anodes.

The cathode current density is preferably maintained in the range of 1.5 to 10 amps per square decimetre (A / dm ^).

Here are some examples:

Example 1

Nickel was electrically deposited to a thickness of 2 mm on the edges .... P.

for titanium cathode plates with a surface area of 1 dm per side, in a conventional cell using cathodes with insoluble anodes from the incoming sulphate electrolyte originally containing 65 g / l of nickel, 150 g / l 5 7 2151

Na 2 SO 4 and 10 g / l H 2 BO at a pH of 3.0 at 65 ° C with a cathode current density of 1 A / dm 2 and a current efficiency of 90%. The cathode plates were pre-roughened by sandblasting No. 1 grade sand to a surface roughness of 0.08 mm. The electroprecipitation was stopped when a total electric current of 170 Ah / dm2 was used, whereby the nickel content of the electrolyte had decreased to 15 g / l. In this case, no detachment of the precipitate was observed and the tensile stress of the precipitate was 1050 kp / cm. The precipitate was easily removed from the cathode plate.

Example 2

Nickel was electrically doped to a thickness of 3 mm on 2 edge-protected cathode plates with a surface area of 1 dm per side in a conventional bag-protected cathode cell with insoluble anodes from an incoming sulphate electrolyte initially containing 65 g / l Ni, 10 g / l Mg and 10 g / l H 2 BO and having a pH of 3.0 at 60 ° C with a cathode current density of 2 A / dm 2 and a current efficiency of 90%. The cathode plate was roughened in advance by sandblasting No. 2 grade sand to a surface roughness of 0.06 U mm. The electroprecipitation was stopped when the nickel content had decreased to 15 g / l, using a total electric current of 220 Ah / dm. In this case, no precipitation detachment was observed and the tensile stress of the precipitate was 1050 kp / cm. The precipitate was easily removed from the cathode plate.

Example 3

Nickel was electrically deposited to a thickness of 5 mm on the edge shield

• ·. O

a cathode plate with a surface area of 1 dm per side in a conventional bag-protected cathode cell with insoluble anodes of incoming sulphate electrolyte originally containing 80 g / l Ni, 10 g / l Mg and 10 g / l H 2 BO 2 and having a pH of 3.0 at 60uC with a cathode current density of 8 a / dm with a current efficiency of 80%. The cathode plate was pre-roughened by sandblasting to a roughness of 0.05 mm. The electroprecipitation was stopped when the nickel content of the electrolyte had dropped to 15 g / l with a total flow rate of 390 Ah / dm.

In this case, no detachment of the precipitate was observed and the tensile stress in the precipitate was 2,980 kp / cm. The precipitate was easily removed from the cathode plate.

Example U

Nickel was electrically deposited to a thickness of 2 mm on 2 edge-protected cathode plates with a surface area of 1 dm on both sides, in a conventional bag-protected cathode cell with insoluble anodes. The incoming sulphate electrolyte initially contained 60 g / l Ni, 150 g / l Na 2 SO 4 and 16 g / l Κ ^ Β0?, Had a pH of 3.0 at 55 ° C and a current efficiency of 82% and a cathode current density of 2 A / dm 2. . The cathode roughness was 0.0 ^ 8 mm (AB finish). At a total current of 150 Ah / dm, which reduced the nickel concentration in the electrolyte to 12 g / l,

Claims (3)

6 72151 2 observed precipitation detachment. The tensile stress of the precipitate was 1050 kp / cm and it was easily removed from the cathode. Example 5 Nickel was electrically deposited to a thickness of 2.0 mm on an edge-protected 2 titanium cathode plate with a mutual surface area of 1 dm in a conventional bag-protected cathode cell with insoluble anodes. The incoming sulphate electrolyte initially contained 72 g / l Ni, 5 g / l MgSO 4, 2 1 + 1 g / l H 2 BO 2 O 5 g / l Na 2 SO 4 and had a pH of 5 x 5 · The cathode current density was 10 A / dm and a current efficiency of 77% and a cell operating temperature of 85 ° C. The cathode plate was originally roughened to 0.05 mm roughness by sandblasting No. 1 grade sand. Precipitation was stopped when the nickel content of the electrolyte decreased to 12 g / l. 2 The tensile stress of the precipitate was 700 kp / cm. No detachment was observed and the precipitate could be easily removed from the plate. 1. A method of electrodeposition of a cathode material made of titanium, sulfuric acid-resistant titanium alloy, aluminum or stainless steel with an adherent but removable, substantially sulfur-free nickel layer having an internal 2. ....... 2 a tension not exceeding 1800 kp / cm and a thickness of 1 mm or more for a uniform area of at least 1 dm of aqueous electrolyte substantially free of chloride, characterized in that the pH of the electrolyte is in the range 1,5 to 5 , 5, the cathode material is protected at the edges and the maximum depth of the profile of the surfaces subjected to the treatment of the cathode material is in the range 0.028-0.078 mm, Method according to Claim 1 or 2, characterized in that the cathode is roughened by sandblasting. Method according to one of Claims 1 to 3, characterized in that the surface roughness of the cathode material is 0.030 to 0.075 mm, 1+. Method according to one of Claims 1 to 1, characterized in that the nickel is recovered electrically using insoluble anodes. Il