DE2245546A1 - PROCESS FOR THE PRODUCTION OF NICKEL, COBALT AND / OR COPPER FROM CHROME-FERROUS ALLOY SCRAP - Google Patents

Description

13,256 20 / egg

PATENT LAWYERS Dr. TCt. n / A". DIETER L0 1/15
Dfpl.-Phys. CLAUS PCi! LAU
Dipl.-Ing. FRANZ 10Η7.Έ.ΝΤΖ
8500 ONLY NB ERQ
1

SHERRITT GORDON MINES LIMITED, Toronto, Ontario / Canada

Process for the extraction of nickel, cobalt and / or copper from chromium-iron-containing alloy scrap

The invention relates to a method for the treatment of chrome-ferrous alloy scrap for the purpose of recovery of contained nickel, cobalt · and / or copper components. The method is particularly intended for use on such alloy scrap in the form of grinding dust, turnings and the like with the aim of breaking it down and preparing the alloy particles so that they can be applied to conventional extraction methods, such as leaching to separate the nickel, cobalt and contained / or copper content.

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Scrap catalysts, residues and waste material that arise in the production of ferrous and non-ferrous metal products, very often form significant nickel, cobalt and / or copper sources. For example, in the production of nickel-containing steel products, large Generated quantities of waste material. This is in the form of grinding sludge, mill and melt scale, sludge residue from pickling tanks, turnings and metal waste from the treatment and processing of steel products. Additionally in addition to iron and carbon, such waste material usually contains considerable amounts of chromium, nickel, Cobalt, copper, manganese and molybdenum.

A number of processes are known which involve the separation of nickel, cobalt and copper from ferrous Alloys are used. For example, when treating ferronickel, the alloy becomes a fine powder ground, then leached in aqueous * oxygenated ammonium sulfate or leached in sulfuric acid to remove the non-ferrous metal components to extract.

The known processes are generally not very satisfactory, as far as the extraction of nickel, cobalt and copper content from ferrous-chromium-containing alloy scrap is affected. Because such a starting material is extremely tough and not friable and

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can consequently only be ground to a leachable particle size with great difficulty. The at Difficulties encountered in milling such a starting material are exacerbated when the material contains abrasives such as aluminum oxide or other alloy metals such as manganese, molybdenum and tungsten. In addition, even after such starting material has been ground into a fine state, it is usually extremely resistant to leaching. It Therefore, very severe leaching conditions and long leaching times are required to obtain nickel and other desirable To be able to extract components such as cobalt and copper from the raw material.

The object of the present invention is therefore to propose a method by means of which ferrous-chromium-containing alloy scrap, which arises from normal industrial processing, can be converted into powder form so that it can be treated in digested form easily by means of conventional extraction processes to remove it Extract nickel, cobalt and / or copper. In particular, it is desired to convert the alloy scrap already to the metal powder, so that it by a conventional leaching in aqueous ammonium sulfate solution or can be treated in sulfuric acid solutions "will be understood that the ₉

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proposed method not only effective but also should be economical.

According to the invention, the intended goal is achieved by the following process steps:

Contacting the alloy scrap with an additive from alkali metal sulfate and / or alkali metal sulfite> Heating the alloy scrap and the additive under conditions which are only reducing with respect to such metals act, whose oxides have a lower energy of formation than iron, to an exothermic reaction between the Alloy scrap and the addition with the resulting conversion of the iron and chromium components to the metal oxides and / or to effect metal sulfides »and then Separation of the reaction product obtained by quenching.

As the exothermic reaction progresses, the alloy matrix breaks of the scrap material together and the iron and chromium components react with the additive, converting them either to metal oxides or metal sulfides. It is thought that the nickel, cobalt and some copper components contained in unalloyed metallic Override state. The remaining copper is believed to be converted to sulfides will. The solid reaction product obtained is exceptionally

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neatly brittle and friable and disintegrates into fine particles when extinguished. Usually the particles have after deletion, a particle size of less than 65 mesh (standard Tyler sieve size).

The end product from the process can go directly to a leaching stage or some other separation process for extraction any containing nickel, cobalt and copper components. The end product needs before not to be ground after the separation process. It also shows that in most cases the extraction rate of nickel, cobalt and copper from the alloy scrap treated according to the invention surprisingly is much higher than the extraction rate from alloy scrap of the same particle fineness, but as an end product of a grinding process.

When carrying out a single-stage treatment, the metal components that react with the additive are limited to those that are in the surface layer of the alloy scrap. Metal components below the surface layer are not attacked by the additive and. therefore do not disintegrate when they are deleted. In general, the surface layer has a thickness of. about 0 * 06 cm. Alloy scrap with a thickness of more than ¹ cm must therefore be treated in two or more stages.

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In each stage the finishing material comes into contact first with the addition under controlled conditions with respect to temperature and reduction attack, the following be explained in more detail, heated and then very quickly extinguished or quenched. This creates a surface layer about 0.06 cm thick after each process step converted to powder form. The treatment is then repeated until the starting material is complete is pulverized.

It will be understood that the term "ferrous-chromium-containing alloy scrap ^11" , as used herein, refers to any alloy scrap which, in addition to iron and chromium, contains economically recoverable amounts of at least one of the elements, nickel, cobalt and copper. In addition to these Elements, the scrap material can also contain a wide variety of other elements that are usually present in alloy scrap material either as an alloy component or as an impurity, which impurities may also have arrived during the collection and sorting of the scrap. Alloy scrap of this type is extremely tough and resistant to grinding processes the reduction takes place even with fine division to a size in which metal components can normally be extracted from alloys by leaching processes, only with large ones

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Trouble.

When carrying out the method according to the invention the scrap material is first brought into contact with an additive consisting of an alkali metal sulfate nem alkali metal sulfite or mixtures thereof. In general, alkali metal sulfite turns out to be somewhat more effective than alkali metal sulfate »sodium sulfate and Sodium sulfite are relatively cheap and therefore 'for the inventive Purposes "preferred® additives"

The respectively required amount of additive depends on the composition of the alloy scrap afo ₀ The higher "for example, 'the iron content ä @ s alloy scrap is all the more addition will generally be necessary," For economic reasons is desirable to use the minimum amount of addition that still is effective and sufficient to pulverize the end product of the process and render it vulnerable to attack using conventional extraction processes. In general, up to 40% by weight of additive can be added; in most cases, however, 15 to 25 % is sufficient »

To ensure that the surface layer of the scrap material embrittled to the desired extent after the quenching or extinguishing process, it is desirable

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It is worth ensuring that the entire surface of the scrap comes into contact with the additive during the heating process. The respective shape that the scrap has »determines the procedure by which the necessary contact is achieved. Are located the scrap material in granular form, for example in the form of abrasive slurry or in ^/ melting furnace scale shape, then scrap material and additive can be stirred together until the particles mesh more or less evenly distributed · The mixture of alloy scrap and additive can then be pelletized by ordinary Pelletier method to ensure that the contact established between the two materials continues during the subsequent heating and quenching processes.

Is the scrap material in the form of rotary pegs or Metal pieces in front of them, this is how contact is made between the scrap material and the addition during the heating process in such a way that the scrap material in a ventilated container is introduced, which is loosely filled with a granulate of the additive. ^

The combination of scrap material / additive is then heated to a temperature at which the scrap material and the addition begin to react with each other. The material can be used, for example, in a stationary

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Heat the melting furnace, rotary kiln or other suitable furnace. Is the mixture of scrap. Material and additive in said "ventilated container" is so heating in a rotary kiln is preferable.

During the heating process it is essential that the atmosphere in the furnace or kiln is controlled so that the conditions are only related to the considered Metal components in the alloy scrap, i.e. in relation to nickel, cobalt and / or copper, do not have a reducing effect on the other hand in relation to the metals, the oxides of which have a higher formation energy, such as iron, chromium, Manganese and tungsten. If the reducing conditions are controlled in this way, it will generally be little or no external heat at all is required to "the Reaction between the additive and the alloy scrap take place once the reaction has started. This is because metals, such as iron and chromium, the oxides of which have a higher energy of formation than nickel, cobalt and copper, oxidize when the scrap metal has reached the temperature necessary for the process according to the invention. Die.by the oxidation of these parts generated heat is usually more than sufficient for complete reaction between the additive and the alloy scrap to ensure.

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A reducing atmosphere can easily be created in the furnace by introducing gases from the partial Combustion of propane or from the steam conversion of Naphtha originate. The reducing gases can be diluted with steam to bring the furnace atmosphere to the required level to match reducing conditions. If the conditions are set in this way, then nickel remains, Cobalt and copper in a reducing atmosphere, while chromium and iron are free to oxidize.

The temperature at which the reaction between the scrap material and the additive starts depends on various factors, such as the composition, the degree of fineness of the scrap material, the amount of fats or other lubricants contained in the scrap, and so on. In general, the temperature required for the onset of the reaction is in the range from 650 to 1150 ^° C. The maximum temperature to which the mixture is to be heated is determined from the melting point of the alloy scrap. Not only is it unnecessary, it is undesirable to heat the alloy scrap to a temperature at which it begins to melt. It is generally preferred to keep the temperature in the oven at about 800 to 900 ° eu.

The reaction between the alloy scrap and the additive leads to a breakdown of the alloy matrix and

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for the oxidation of the iron and chromium components. As already indicated above, the oxidation reaction is exothermic away. Once the reaction has started, there is generally no more external heat input required to continue the reaction «, The end of the reaction can be determined by monitoring the temperature in the Determine the furnace. When the temperature begins to drop, the reaction is largely complete »

After the heating process, the reaction product is extinguished in order to instantly cool the material and burst into fine particles. The deletion also prevents unwanted oxidation of the nickel, cobalt and copper content in the reaction product. The product can be quenched in a water tank; it lets You are also deterred by allowing a continuous high velocity stream of water on the material directs. .

The nickel, cobalt and copper components can be derived from the quenched quenching product through several different ones Separate measures. Some of the desired proportions can be made with magnetic devices for the purpose of be removed after refining. The desired proportions can also be achieved by 'conventional Separate leaching process. In most cases you can

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the fractions can easily be extracted from the end product of the process according to the invention by oxidation leaching with aqueous acid at elevated pressure and elevated temperature. According to these methods, the quenched product is dispersed in an aqueous sulfuric acid solution containing at least the stoichiometric amount of acid required to combine with the nickel, cobalt and / or copper contained to form sulfates. The resulting slurry is heated to about 120 to 127 ^° C. with continuous stirring and under an oxygen partial pressure of about 1.05 to 2.1 kp / cm. It usually takes 3 to 4 hours to extract 90% or more of the nickel and cobalt.

Alternatively, the end product of the process according to the invention can also be leached using an ammoniacal ammonium sulfate solution. A sufficient leach slurry contains about 150 g / L free ammonia (introduced into the solution as, for example, ammonium hydroxide), about 300 g / L ammonium sulfate, and a sufficient amount of the final product to give 60 g / L nickel plus cobalt plus copper in solution. The slurry is stirred to about 85 to 95 ⁰ C under an oxygen pressure

of 1.4 kp / cm heated to the nickel, cobalt · and / or Bring copper components into solution.

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The invention is illustrated below with the aid of exemplary embodiments play explained in more detail.

Example 1;

The specific method described below carried out in accordance with the present invention is, in connection with the treatment of grinding machine waste, a high-temperature-resistant nickel and cobalt-containing alloy. The size of the Alloy particles were approximately 62% less than 65 mesh (standard Tyler screen size) with the remainder less than 35 mesh. The bulk density was -2.67 g / cm. The material had an analysis (in percent by weight) of 53% nickel, 6.7% cobalt, 10% iron, 3.5% molybdenum, 18% chromium, 0.25% Tungsten and 0.23% sulfur.

A dry mix was prepared comprised of about 3 parts by weight of the abrasive waste and one part by weight of sodium sulfate particles less than 35 mesh in size. Using conventional procedures, the mixture was formed into briquettes with an edge length of 6 2.54 x 0.18 cm. The briquettes were roasted in a rotary kiln, with direct flame heating by the burner at a temperature of 875 ⁰ C. The dwell time of the briquettes in the rotary kiln was 30 minutes. The atmosphere inside the rotary kiln had

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following analysis (volume percent on dry basis): 78% N ₂ , 4.0% H ₂ , 9.0% CO ₂ , 1.0% O ₂ , 6.0% CO, 0.8% COS, 0.2 % CH and less than 50 ppm S0 _? .

Xy c.

Following roasting, the briquettes were quenched in water and then in a ball mill for 15 minutes ground. Following milling, 91.2 percent by weight of the material had a particle size of less than 65 mesh and the rest less than 28 mesh. A chemical analysis of the digested material showed (in percent by weight): 41.2% nickel, 5.5% cobalt, 8.84% iron, 0.06% molybdenum, 13.2% chromium, 18% oxygen, 0.26% tungsten, 6.69% Sulfur and 0.14% copper.

The material was then packed into an autoclave containing about one mole of sulfuric acid per mole of the material. The acid was at an oxygen pressure of 2.1 kp / cm held at a temperature of 12O ⁰ C. After 4 hours the liquid was separated from the solid residue.

Analysis of the separated liquid showed that 98.4% of the nickel and 95.3% of the cobalt came from the raw material serving alloy grinding dust were extracted and dissolved in the liquid.

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Example 2;

Then the procedure for treatment of alloy turnings.

The starting material was a nickel-cobalt alloy with a fineness of approximately 99% over 10 mesh, which in The form of turnings and curls of irregular shape was present. The dimensions were approximately 0.6 10.16 χ 0.5 cm. The material was contaminated with cutting or cooling oil. The result was an analysis (in percent by weight) of 53% Winding, 7.0% cobalt, 10% iron, 3.5% molybdenum, 20% chromium and less than 1% sulfur.

Two parts by weight of the turnings were combined with one part by weight of sodium sulphite in a perforated can with a capacity of about 235 cm. It remained in the rotary kiln for 30 minutes. The atmosphere in the rotary kiln (measured in volume percent on a dry basis) was 80 to 85% N ₂ ^ 1 to 4% H ₂ , 8 to 12 CO ₂ , 1 to 1.5% O ₂ , 2 Ms 6% C0 _s 0.8 to 1.2 COS and 0.1 to 0.5 C ₃ H analyzed.

The can and its contents disintegrated in the oven and the disintegrated mass was quenched in water. After the deterrent the material was in a ball mill for 15 minutes

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ground. The partial size of the taken from the ball mill Materials was 70.5% less than 28 mesh. A chemical analysis of the extracted material showed 37.6% nickel, 6.48% cobalt, 13.0% iron, 1.2% molybdenum, 10.8% chromium, 0.05% tungsten, 7.62% sulfur and 16.2% oxygen.

The material was made in the same way as in Example 1 has already been explained. Analysis of the liquid found 97.9% of the nickel and 94.8% of the cobalt extracted and dissolved in the liquid.

The results of experiments 1 and 2 clearly show that that the treatment of nickel- and cobalt-containing alloy scrap by the method according to the invention to one Extraction of more than 98% of the nickel and 94% of the cobalt results.

The method according to the invention is thus essentially characterized by the following features:

Iron-chromium-containing alloy scrap in the form of grinding dust, turnings or the like is treated to make the alloy to blow open and thereby facilitate the extraction of the nickel, cobalt and / or copper contained. the

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Treatment involves contacting the alloy with an alkali metal sulfate or an alkali metal sulfite additive and the subsequent heating of the alloy and additive under controlled reducing conditions, to initiate and carry out an exothermic reaction «The reaction product is then quenched, to blast it to a fine-grained state by subjecting it to further treatment for the purpose of extraction the nickel, cobalt and copper components are accessible.

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Claims (5)

Patent claims: 1. Process for the extraction of nickel, cobalt and / or copper from chromium-iron-containing alloy scrap in Form of grinding dust, turnings or the like by the following process steps: bringing the alloy scrap into contact with an additive of alkali metal sulfate and / or alkali metal sulfite; Heating the alloy scrap and additive under conditions unique to such metals have a reducing effect, the oxides of which have a lower formation energy than iron, to an exothermic Reaction between the alloy scrap and the additive with the resulting conversion of the iron and chromium components to the metal oxides and / or metal sulfides to effect, and separation of the reaction product obtained by quenching. 2. The method according to claim 1, characterized in that the nickel, cobalt and / or copper in a form is obtained, in which it can be extracted in a subsequent leaching process. 3. The method according to claim 1 or 2, characterized in that the temperature to which the alloy scrap 309822/0 727 and heating the additive, in the range of about
800 to 90O ⁰ C is. 4. The method according to claim 1 or 2, characterized in that the alloy scrap with about 15 "to 25 percent by weight Additive is brought into contact. 5. The method according to claim 1 or 2, characterized in that that the addition is sodium sulfate or sodium sulfate. 309822/0727