FI61205B - PROCEDURE FOR THE PURPOSE OF RELEASE TO THE COVER AND FORWARDING OF NICKELS - Google Patents

Description

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Canada (CA) 232831 (71) Inco Limited, Toronto-Dominion Center, Toronto, Ontario, Canada (CA) (72) David Llewellyn Jones, Mississauga, Ontario, Kohur Nagaraja Subramanian, Mississauga, Ontario, Canada (CA) (71 * This invention relates to the alloying of copper with aqueous nickel metal and is particularly suitable, although not exclusively, for the recovery of nickel metal from nickel metal to nickel metal. This invention relates to the alloying of copper from aqueous solutions with nickel rock.

In the following presentation, all percentages are by weight. The extraction of nickel from the clay by contacting the aqueous clay slurry with chlorine is an effortless first step to obtain a nickel-containing solution from which the purified nickel product can be recovered, e.g., electrolytically. in the presence of copper and sufficient chloride ions, typically 100 g / l or more to ensure the solubility of cuprous ions. In such a process, the reaction is believed to take place between the metal rock and the copper ions in solution, with chlorine acting to regenerate the copper ions. Such a procedure has been known for some time and a more recent variant of adjusting the redox potential during extraction to achieve selective dissolution of some of the metals in the clay is described in CA Patent 967,009, 2661205.

At the end of the extraction, it is generally necessary to reduce the amount of dissolved copper in the nickel-containing extraction solutions so that the following purification and electrolysis operations can be carried out efficiently. The well-known technique for reducing the copper content of solutions involves precipitation with less noble copper. the desired effect is that it introduces an impurity into the solution which must be removed later, whereas the use of elemental nickel for this purpose is necessarily expensive. A commercially attractive proposal involves the use of metal stone for precipitation. In U.S. Patent 2,180,520, a copper-nickel solution is treated with a copper-nickel metal stone to effect copper deposition. The preferred metal stone is one that is relatively low in sulfur, i.e. 55,355 »nickel-copper solution is treated with elemental sulfur together with a metal rock having an atomic ratio of nickel to sulfur greater than 1. In one example of this patent, nickel-copper rock is extracted by introducing gaseous chlorine into a boiling aqueous slurry of metal contains about 20% elemental sulfur, and a solution of 50 g / l of dissolved copper, When this residue is stirred in contact with the solution for a further 2 1/2 hours without adding more chlorine, a small part of the dissolved copper and the dissolved copper content precipitates the new decreases to Ui g / l. The rest of the copper is removed by reaction with fresh nickel rock with an atomic ratio of nickel to sulfur of more than 1, which is added to the slurry.

The present invention is based on the finding that nickel metal rock can be made a more effective precipitant for copper by extracting part of its nickel content without the formation of elemental sulfur.

The reason for the improved precipitation properties of nickel metal rocks activated by partial extraction is clearly not understood. Whatever the mechanism, it has surprisingly been found that (a) the precipitation efficiency obtained with a particular metal rock, judged by, for example, reaction kinetics, is greatly improved by partial leaching (b) sulfur whether the atomic ratio of nickel to sulfur is greater than or less than 1,

The process of the invention for precipitating copper from an aqueous solution containing chloride by means of a nickel metal rock is characterized by extracting 15-60% of the nickel containing the metal stone by reacting the slurry obtained by slurrying the metal with an aqueous solution containing chloride and copper ions. the partially extracted metal-rock is contacted with a solution from which the copper is alloyed, without further contact with gaseous chlorine or oxygen.

Chlorine or oxygen acts as an oxidizing agent, regenerating copper ions from cuprous ions in an inexpensive manner and without introducing unwanted foreign ions into the solution. When oxygen is used, a suitable acid addition is required during the extraction operation and it is therefore advisable to use chlorine. an aqueous slurry containing copper ions with at least 10 g / l of dissolved copper in contact with chlorine to partially or completely dissolve the nickel from the metal rock.

The metal rock, which has been partially extracted and then used for precipitation, is suitably the same material from which the nickel is to be recovered. However, this is by no means essential and any alternative available nickel metal rock can be used for partial leaching and precipitation.

Most preferably, the same metal rock is used, and the extraction and precipitation steps are combined to give a process for recovering nickel from a nickel metal rock, in which the metal rock is slurried in an aqueous solution containing at least 10 g / l of copper, chlorine is fed to the slurry. 15-60% of the nickel in the water dissolves, the chlorine feed is stopped before all the nickel has been extracted from the metal rock, the partially extracted metal rock is contacted with an extraction solution containing nickel and copper to precipitate copper from the solution, and the alloyed copper and extraction residue are separated from the solution.

If desired, the metal stone can be treated in two or more batches during chlorination.

In the most preferred nickel recovery process involving successive extraction and precipitation reactions resulting from a single addition of a metal rock to a copper-containing solution, the amount of extraction, i. Whereas the duration of chlorination must be chosen in such a way as to ensure that the amount of metal rock remaining when the chlorine flow is stopped is at least sufficient to reduce the amount of copper in solution to the desired level;

Chlorine extraction of a metal rock, whether carried out to completely dissolve the nickel to be recovered or to produce partially extracted metal rock for use in the precipitation of copper, is necessary in the presence of copper ions. This is to ensure efficient extraction of nickel while minimizing sulfate formation. In practice, at least 10 g / l and preferably 30 g / l or more of copper must be present in the solution to which the nickel metal rock is attached. It is to be understood that while it is convenient to describe the extraction and precipitation processes separately, the processes may in practice occur simultaneously as chlorine is blown through the metal-rock slurry. Thus, precipitation can be considered as a competitive reaction that can occur during chlorine extraction. Since any precipitation associated with the extraction process results in a reduction in the amount of dissolved copper, it is necessary to select the initial amount of copper in the solution according to the composition of the metal liquor to be extracted. For example, a copper content of 30-40 g / l is desirable when the sulfur content of the nickel metal rock to be extracted is of the order of 20 *.

The extraction reaction can be carried out at temperatures as low as 60 ° C, but preferably the metal rock slurry should be kept between 90-110 ° C. The temperature can generally be maintained by the exotherm of the extraction reaction.

For this new precipitation by means of a partially extracted nickel metal rock, the most useful application is found in an improved overall process for the recovery of nickel impurities from nickel metal. The most preferred nickel recovery process of this invention comprises the steps of (i) slurrying the impure metal rock into an aqueous copper-containing solution and partially extracting with chlorine; (il) the chlorine flow is stopped and the partially extracted methyl chloride is allowed to precipitate copper out of the extraction solution; (lii) separating the extraction solution from step (ii) from solids containing precipitated copper and scrap metal; (iv) the extraction solution obtained from step (iii) is purified by solvent extraction and / or ion exchange to remove impurities such as iron, copper, cobalt, arsenic, lead and bismuth; (v) the purified solution obtained from step (iv) is electrolysed to recover pure nickel and form chlorine for recovery to extract additional metal rock in step (i) above and step (vi) below; (vi) the solids from step (iii) are slurried in the spent electrolyte from step (v) and treated with chlorine to achieve complete extraction of the solids, resulting in a solution of copper and nickel for recycling to step (i) with fresh metal rock and a substantially sulfur residue.

To ensure the efficiency of complete extraction of step (vi), a portion of the copper and nickel-containing solution obtained in this step is recycled internally, thereby ensuring the desired amount of dissolved copper at the beginning of this complete extraction.

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Here are some examples!

Example 1 i * ». > n

The partially extracted metal stone was prepared as follows; 200 g of granulated metal rock, which by analysis contained; nickel 70.8% copper 0.5 * +% cobalt 1.1 * 8% iron 0.38% sulfur 26, U% was slurried in 750 ml of a slightly acidic chloride solution containing 100 g / l nickel and 30 g / l copper, at 90 ° C, Chlorine gas was fed to the slurry at a rate of 2 x 5 g / min, after 10 minutes the chlorine flow was stopped and analysis of the extraction solution showed a nickel content of 155 g / l and a copper content of 10.9 g / l, indicating that precipitation had taken place. The residue comprised 167 μg of partially extracted metal rock free of elemental sulfur (determined by hot toluene washing) and containing by analysis (nickel extracted from the original metal stone was 31%): nickel 58.3% copper $ 8.5 sulfur 30 .9% This partially extracted metal rock was used for copper precipitation as follows; 150 g of partially extracted metal rock was added to 750 ml of an acidified copper sulfate solution containing 10 g / l of copper at 90 ° C. The slurry was mixed and sampled at 30 minute intervals and the copper concentrations are shown in Table 1 below. For comparison, precipitation was carried out in the same manner as described above, except that 150 g of the original, unextracted granulated metal rock was used instead of the extracted metal rock,

Table 1 Metal rock used_Precipitation time (min) _Copper in solution (g / l)

Partially extracted 0 10.0 30 1.03 60 0.05 90 0.002

Thus, it can be seen that the precipitation carried out according to the process of the invention reduced the amount of copper in the solution in 30 minutes to a lower level than that obtained after 90 minutes of precipitation with an inactivated metal rock,

Example '^ 2 r * i * i i v

A nickel extraction test was performed using the same metal rock that formed the starting material in Example 1. A first sample (55 g) of this metal rock was chlorinated in 750 ml of an acidified solution containing 97-5 g / l of nickel and 9.0 g / l of copper by blowing chlorine. 1.6 g / min for 30 minutes through a slurry that rose from 92 ° C to 103 ° C. At this time, a second portion of i (95 g) of the same metal rock was added to the slurry and the chlorine flow was continued for another 1 * 0 minutes. This time was sufficient to partially extract the second batch of metal rock, at which point 60% of the nickel present dissolved, the chlorine flow was then stopped, and a sample of the residue was removed for analysis. Stirring of the slurry was continued and the amount of copper in the solution was determined at certain intervals. The results of the precipitation can be seen in Table 2 below:

Table 2

Time (min) _ Addition of metal rock (g) Copper in solution (g / l) 0 55 9.0 30 95 N.D.

70 * - 7.2 150 - 0.85 2U0 - 0.10 380 - 0.06

Chlorine flow was stopped at this point by N.D. = not specified

The residual sample from the duplicate, taken after 70 minutes of extraction, was washed with hot toluene to remove any elemental sulfur formed in the complete extraction of the first sample of metal rock, and then analyzed for nickel and sulfur. that no Ni 2 S 2 phase was present. Thus, it is found that the nickel sulfide which acted as a precipitant from the moment the chlorine extraction was stopped was a metal rock with a Ni / S 2 O 4 ratio well below 1.

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Example 3

The following experiment illustrates the application of the precipitation process of the invention to a practical nickel recovery formula from nickel metal rock, Step 1 extraction; * ....... a “\! · τ * τ ^ 2000 g of granular metal rock which, according to analysis, contained by weight: nickel 77.2% copper 0, i * 9% cobalt 1.19% iron 0.80% 19% sulfur was added to 8.6 liters of a chloride solution containing 160 g / l nickel and 10 g / l copper at 60 ° C, chlorine was blown through the slurry at 20 g / min for 30 minutes, during which time the slurry temperature rose boiling point (110 ° C). The chlorine flow was stopped and the slurry of partially extracted metal rock from which 30% of the nickel had been extracted was stirred for a further 105 minutes to effect copper precipitation. The solution was then filtered and found to contain 250 g / l nickel and 0.37 g / l copper. similarly, this solution was used for the electrolytic purification of nickel.

2, stage extraction:. «R 'w *' 1 1 '' 8.2 liters of spent electrolyte from the electrolysis operation, containing 75.5 g / l of nickel and no copper, was mixed with 1.9 liters of chloride solution ^ containing 160 g / l of nickel and h-0 g / l copper, A solid residue from the step 1 extraction (157 g) was added to this solution at 7 ° C and pH 1.5 · The slurry was then stirred and chlorine was fed at a rate of 20 g / min. quantitatively for 68 minutes. At this point, the chlorine flow rate was reduced by 50/2 and stopped after another minute, as the chlorine in the exhaust gases indicated that the reaction was complete. During the extraction, the slurry temperature had risen to boiling point, but by the end of the reaction the slurry had cooled,

The slurry was filtered and the residue was found to be substantially sulfur (by analysis by weight) copper a 0.15% nickel 1.16% cobalt 0.09% iron 0.55% sulfur 97, ^% 8 61205

The resulting filtrate could then be recovered 1, by performing an extraction with a fresh metal rock sample, if necessary after adjusting the appropriate copper content.

It is apparent from the typical examples above that when reference is made herein to the treatment of a copper-containing solution with an activated (i.e., partially chlorinated) nickel metal rock, this metal rock need not be activated prior to its addition to the copper-containing solution. In fact, the metal rock can be activated in the mixture itself, as was the case in Examples 2 and 5 above.

Claims (3)

9 61205 A method for precipitating copper from an aqueous solution by means of a nickel metal rock, characterized in that 15-60% of the nickel contained in the metal rock is extracted by reacting the slurry obtained by slurrying the metal rock with an aqueous solution containing chloride and copper ions and reacting with gaseous chlorine or oxygen. is contacted with a solution from which copper is precipitated, without further contact with gaseous chlorine or oxygen. Process according to Claim 1, characterized in that the metal rock is slurried in an aqueous solution containing at least 10 g / l of copper, chlorine is introduced into the slurry to dissolve the nickel contained in the metal rock, chlorine conduction is stopped after 15-60% of the nickel has been extracted and with an extraction solution containing nickel and copper to precipitate copper from the solution, Process according to Claim 2, characterized in that the metal rock is extracted in two or more batches, the first batch being completely extracted and then the second batch being added and partially extracted so as to remove 15 to 60% of the nickel, 1 *. Process according to Claim 2 or 3, characterized in that the copper-containing solution contains at least 30 g / l of copper.