DE595688C - Process for separating cobalt from nickel - Google Patents

Description

Process for separating the cobalt from the nickel The separation of the cobalt nickel in its aqueous solutions is used in technology - apart from special cases - exclusively due to the heavier acid solubility and therefore lighter ones Precipitability of cobalt sesquioxide compared to that of nickel. As an oxidizing agent chlorine is used here, either in gaseous form or as hypochlorite. To be as pure as possible To obtain a nickel-free product, one has to repeat the precipitation or the solution keep pissed off. In both cases you need much more than what is theoretically required Amount of filler, which makes this process expensive. Next is that gained Cobalt hydrate should only be used directly for the preparation of oxides. For fabrication of oxydulhydrate, salts or metal must be removed by further expenditure of chemicals only be reduced. Finally, the nickel-containing final liquors are unsuitable for the direct extraction of nickel metal, the nickel must first be used as Hydrate or carbonate precipitated, the precipitate dried, calcined, washed and then be reduced to metal in a cumbersome manner.

The following describes a method that avoids these shortcomings and at low cost - the chemicals used become usable Form or recovered in the cycle - the representation of a cobalt oxide compound on the one hand and electrolyte nickel on the other hand in a few manipulations.

The method is based on the various, first used by the inventor more closely examined behavior of cobalt and nickel salt solutions towards ammonia and its salts. It is known that ammonia in cobalt or nickel solutions is a Causing precipitation, which with further addition of the precipitant again in solution goes. It is also known that copious amounts of ammonium salts precipitate Prevent cobalt or nickel from ammonia.

It has now been found that cobalt solutions require a much higher effort of ammonia as well as ammonium salts is necessary, -to the initially formed To dissolve precipitate again or not to allow it to occur at all, as with nickel salt solutions, Furthermore, that mixed solutions of both metals with the gradual addition of ammonia initially both metals, but always more from cobalt than from nickel, separated until after a certain and for all mixing ratios are exceeded Both metals equal the amount of ammonia that precipitated nickel back in solution goes, while the amount of excreted cobalt decreases only slowly. The border and above all the speed at which the nickel deposit dissolves again will the temperature, the concentration, the time and the ammonium salt content of the solution, but not influenced by the ratio of the two dissolved metals to one another.

The largest amount of the precipitated metal compounds is about 2.25 111.01 NH, per z moles of Co-Ni. While up to 97 % of the cobalt is precipitated, the much larger amount of nickel remains in solution, especially at low temperatures. With further addition of ammonia, the proportion of precipitated nickel decreases very quickly, while that of cobalt decreases only slowly, and at higher temperatures it even increases at first. With the addition of 6 moles of N H3, the precipitate is practically nickel-free, while around 80% of the cobalt has precipitated.

If ammonium salt is added to the mixed solution beforehand, it becomes nickel-free of precipitation reached earlier, but also the percentage of precipitated cobalt depressed. In all cases, increased temperature causes a greater yield, with the same addition of ammonia, however, there is also a greater nickel content in the precipitate.

The more concentrated the solutions, the smoother the separation are and the faster the procedure is carried out, because at great dilution considerably more nickel precipitates, while the concentration on the deposition of cobalt is of lesser importance.

The cobalt precipitates are green to blue colored basic salts of the formula: q. # Co (O H) 2 # Co S O q., Which filter and wash out very well permit. They can be turned into oxide by glowing strongly, by treating them with a little alkali (2 mol to 5 mol of Co) in Oxydulhydrat, by treatment with acid in the appropriate Salt to be transferred. They can also be used for the immediate production of a suitable Electrolytes can be used for the deposition of electrolyte cobalt.

The remainder of the cobalt still in solution can be removed by heating the solution can be obtained with alkali or other hydrates or carbonates, since in the presence of ammonium salts and especially of free ammonia cobalt by alkali is more easily deposited than nickel, while this is with ammonium salt-free solutions behaves in exactly the opposite way. Since this precipitate is rich in nickel, will it was expediently dissolved again and added again at the beginning of the procedure. That at When heated with alkali, any free ammonia that escapes can easily be caught and restored be used.

The remaining nickel lye contains a lot of ammonium salt and contains free ammonia. It is evident that from this liquor the nickel is easily electrolytic can be obtained, especially when working with sulfuric acid starting solutions would have. The nickel-free final liquor can either be neutralized using waste acid on ammonium salt (fertilizer salt) can be processed, also by heating with milk of lime Drive out the ammonia and return it to the process.

Of course, the nickel lyes can also be acidified on nickel ammonium sulfate be evaporated.

According to the above, there are various design options of the procedure, the appropriateness of which is determined by the relationship of the two metals in the starting solution, the type of this solution and the desired one End product. It is also conceivable that the separation by means of ammonium salt and Alkali or other hydrates are carried out alone, i.e. without the addition of ammonia, if only small amounts of cobalt are removed from a pure nickel lye should. You can also start with all of the cobalt with a small part of the nickel precipitate with ammonia and alkali and then treat the precipitate again for yourself.

You can also do that after the main amount of cobalt has been deposited Acidify the filtrate and separate the nickel from the remaining amount of cobalt by fractionating Bring crystallization of the poorly soluble nickel ammonium sulfate.

In certain cases it will be more advantageous to use the concentrated mixed solution of the two metals to flow into the appropriate amount of ammonia and then if necessary to dilute or to heat or to use both agents. Ammonia salt can be added to both the mixed solution and the ammonia solution be added, it can also be produced in the mixed solution in a known manner.

Finally, the rest of the cobalt in the nickel lye can also get through Oxidation by means of air, hydrogen peroxide or other oxidizing agents and subsequent heating with steam are precipitated as a purpureo compound.

Finally, there is also a combination of the method with the known Precipitation of nickel by means of dicyandiamidine is possible by first adding the main amount of the cobalt is deposited nickel-free according to the invention and then all of the nickel by means of Dicyandiamidine precipitates cobalt-free. This can be seen from the nickel deposit Regenerate dicyandiamidine. Execution example game I 2000 cms a neutral sulphate solution with 14.75 g of Co and 14.65 g of Ni are mixed with 16. g of ammonium sulphate added, diluted to 225o cm3 and after adding 225 cm 'of ammonia (o.9io) under Stir heated to 60 ° C; the precipitate filtered off with suction and washed with cold water.

Precipitate I, filtrate I. II -Precipitate I is dissolved in sulfuric acid dissolved, the solution neutralized with sodium hydroxide solution and diluted to iigo cmg, then after adding 60 cm3 of ammonia (0.910) heated to 45 ° C. with stirring, the precipitate sucked off and washed.

Precipitate II, filtrate II.

The precipitate contains: 0.93.6 g Co, trace Ni.

III Filtrate I including wash water is heated to boiling and the precipitate sucked off.

Precipitate III, filtrate III.

The filtrate III contains: 1 3.2 g Ni, 0.4 g Co. IV precipitate III is dissolved in sulfuric acid and, after neutralization with Na OH, together with filtrate II with a fresh starting solution of the two metals, containing 14.75 as in I g Co and 14.65 g Ni, combined. Now no more ammonium salt is added, as filtrate II contains sufficient of it. Corresponding to the greater amount of metal in solution, a greater amount of ammonia would also be required; but since filtrate II contains such, only 90 cm3 of conc. Ammonia (o, 9io) applied. The total amount of liquid is brought to 250o cm3 and heated to 60 ° C. while stirring, the precipitate is suction filtered and washed.

Precipitate IV, filtrate IV. V Precipitate IV is dissolved in sulfuric acid, the solution is diluted to izoo cm 'after neutralization with sodium hydroxide solution and, after addition of 70 cm3 of ammonia, heated to 60 ° C., the precipitate is suction filtered and washed.

Precipitation V, filtrate V.

Precipitate V contains: 14.54 g Co, 0.07 g Ni.

'VI Filtrate IV is again heated to boiling and the precipitate sucked off.

Precipitate VI, filtrate V1.

Filtrate VI contains: 1 3.2 g Ni, 0.4 g Co. The intermediate products - filtrate V and precipitate VI - are added to the next batch as in IV, so that the end products of the separation process are passed through the cobalt precipitates II and V and through the nickel end liquors III and VI are marked.

Claims (1)

PATENT CLAIMS: i. Process for separating cobalt from nickel by precipitation of cobalt from solutions containing cobalt and nickel, characterized in that that the cobalt by means of ammonia as a basic salt, optionally after increasing the temperature, is brought to the deposition, with more than 2.25 per mole of Ni-Co Mol NHg are to be used. z. Method according to claim i, characterized in that by adding ammonium salts and heating with such bases that cause decomposition of ammonium salts are made free of ammonia in the solution and cobalt as basic salt is excreted.