DE2348005A1 - PROCESS FOR THE EXTRACTION OF COPPER AND / OR ZINC FROM WASTE - Google Patents

Description

Π. 12 Dr Be/U

Albright & Wilson ltd., PO Box 3, Old.bur.v. Warley, Worcestershire, England

Process for the extraction of copper and / or zinc from

Waste

The invention relates to the extraction of copper and / or zinc from waste. The invention is applicable to Extraction of copper and / or zinc from various cheap, these low-volume ores, scraps and industrial by-products, which are not can easily be treated by means of conventional work-up methods.

It is known to extract copper from substances with a low level of copper- content, such as mine residues and spoil heaps to be leached out using solutions that have a high ammonia content have, and the copper from the solution by evaporation or stripping off the ammonia with steam. Other methods of extracting copper from the solution are also known, such as acidification with subsequent cementation or electrolysis. These Process suffer from the disadvantage that either expensive devices to facilitate the extraction are required with recycling of the ammonia or that the alkalis containing ammonia are lost-

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walk.

There was an improved, simplified method for Extraction of copper from the said substances with low copper content found that the need bypasses the use of complex devices and allows the alkalis to be recycled, with the ammonia losses be kept to a minimum. The process allows copper to be extracted from materials that Contain iron, brass and other metals and can interfere with the usual leaching processes and are permitted the extraction of copper in great purity. Another advantage is that the implementation The system used in the process can be made of normal mild steel, because of the corrosion is low due to the attack of the ammonia-depleted solution.

It has been found that waste containing copper can be leached with an aqueous solution, which contains ammonium bicarbonate. The waste liquor obtained can, if necessary, then after filtration saturated with carbon dioxide, whereby ammonium bicarbonate is regenerated in the solution and basic copper carbonate is precipitated. After filtering, the liquor containing ammonium bicarbonate can be leached again of further copper-containing material can be used.

The method is also applicable to the recovery of zinc from this containing in small amounts

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metallic and oxidic residues and can also be used to remove copper in an effective manner To obtain material that contains a mixture of copper and zinc ·.

The method of the invention is accordingly characterized characterized in that wastes containing copper and / or zinc, according to the definition given, with a aqueous ammonium bicarbonate solution are brought into contact in the presence of oxygen and from the Waste the copper and / or zinc in 3? Orm of their ammine complexes is leached out.

Atmospheric oxygen is preferably used as the oxygen, which is produced by venting the lye is made available.

"Waste" includes, for example, metal mixtures containing copper and / or zinc in the form of scrap, Waste from electrical devices, oxidic ores, mining residues, mineral overburden components, Alloys, slag and the scrap formed in the manufacture and shaping of metals is understood. In a typical form, the waste contains other metals or non-metallic ones Impurities. The invention is particularly applicable to scrap, the iron and / or Contains iron-based alloys. The expression "containing copper and / or zinc" means that copper and / or zinc as free metals either alone or in mixtures or in an alloy or in Form of their oxides are present. To a satisfied

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To achieve economic recovery, if coarse-grained substances are assumed, it is necessary to that the waste is appropriately ground or crushed so that there is sufficient contact between the copper and / or zinc and the ammonium bicarbonate solution is ensured. The extent and type of shredding depends on the nature of the waste away. In those cases where the copper and / or zinc are somewhat difficult to access, as is the case with isolated ones Wiring the pail is often preferred to grind the waste in the presence of the bicarbonate solution. Alternatively, the waste can also be broken into pieces prior to contact with the aerated ammonium bicarbonate solution to be broken up. In any event, it is generally preferred to ensure that between waste and the solution by stirring the waste and / or circulating the solution through the waste a relative Movement is created to encourage the reaction between the 3 phases.

The method according to the invention works to a certain extent Extent at any concentration of ammonium bicarbonate in the solution used for leaching, however usually the liquor 5 to 250 g per liter, preferably 50 to 150 g per liter of ammonium bicarbonate, e.g. 100 g per liter. The pH value can preferably be 8.3 to 9.5. The presence of excess Ammonia is not required and if the process is operated with scrap containing ferrous material, this is inexpedient since it has been found that the formation of iron hydroxide by the presence of excess carbonate ions is inhibited. the

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Solution is preferably kept ventilated, e.g. through Bubbling air through the inlet stream of a circulating solution. The temperature of the solution is expediently at ambient temperature, but the process can be carried out over a wide temperature range between the freezing point and the boiling point of the solution work. However, for economic reasons it is not expedient to carry out the process outside of a Range from E to 45 ° 0.

The contact between the solution and the waste can Maintained until a sufficient concentration of copper and / or zinc is saturated has been achieved. According to a typical example, when using a solution at 100 g / per liter Ammonium bicarbonate dissolved 20 to 30 g / per liter of copper and / or 6 to 9 g / per liter of zinc. When using Solutions containing 150 g / liter of ammonium bicarbonate can contain up to 46 g / liter of copper and / or 14 g / Liters of zinc can be dissolved. When using solutions containing up to 250 g / liter ammonium bicarbonate, Concentrations of up to 71 »7 g / liter of copper can be achieved, but such a solution can only obtained by gradually adding ammonium bicarbonate and tends to be unstable, when she is educated. When the concentration of Copper and / the zinc has reached a sufficient value to allow economic extraction, the solution can be separated from the remaining waste e.g. by filtration and copper and / or zinc can be isolated. There are several methods of isolation, including acidification followed by

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Cementation or electrolysis and evaporation possible. The preferred method, however, is to add carbon dioxide, the plucking and / or zinc in the form to precipitate their basic carbonates and to regenerate the leach solution. The precipitated carbonate can be separated by filtration and the regenerated solution can be reused in the leaching process will.

The carbonates of copper and zinc can be precipitated in the pH range 8.0 to 7.2. It is possible, to effectively precipitate all zinc from alkalis containing only zinc by a simple one Gas introduction method at atmospheric pressure. A more effective one There is a method regarding the expenditure of time and the utilization of gaseous carbon dioxide but in doing the gassing at increased pressure. A satisfactory precipitation takes place e.g. when a total pressure of 2 atmospheres is used, but pressures above this can also be used Value can be used. If copper is only present in the lye, it can be gassed at 1 atmosphere Pressure up to $ 60 of the existing copper precipitated will. In order to achieve better yields of copper, however, it is expedient to use the step of gasifying in Carrying out carbon dioxide at elevated pressures, preferably at 2 atmospheres total pressure or above. Most of the copper is precipitated and the small amount that remains in the solution is acceptable because re-using the solution in the leaching step increases the rate of dissolution the waste is improved by its presence.

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When both copper and zinc are present in the solution are, the zinc tends to preferentially precipitate at a higher pH value, so that a crude separation of zinc and This makes copper possible. Zinc-rich traction is obtained at a pH between 8.0 and 7 »7 and a copper-rich traction at the pH between 7.7 to 7.2.

However, the zinc-rich traction can do a great deal Copper contained in solution and, although the second

it

! Traction consists mainly of copper, / can be a Zinc contamination may occur. Besides, it is difficult to obtain economically significant amounts of the copper present in the solution after removal of the Remove zinc that is left behind.

Therefore, in order to obtain copper in acceptable purity and quantity from solutions containing both zinc and copper amine complexes a two-stage single-gas process with carbon dioxide before v / ends is preferably included. The first stage consists in the introduction of carbon dioxide gas at a relatively low pressure, e.g. below 1.5 atmospheres, preferably at atmospheric pressure, to practically the entire amount of zinc and up to to precipitate $ 60 of copper in the solution. The precipitate is then filtered out of the solution or other appropriate measures removed, and the solution is then the introduction of carbon dioxide gas at a relatively high pressure, for example above 1.5 atmospheres and preferably 2 atmospheres subject.

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The precipitation that occurs during the first gassing at relatively low pressure is obtained, then preferably dissolved in the filtrate from the second gasification stage, after adjusting the pH by aerating the solution and adding a small amount of ammonia to replenish the losses to the atmosphere and to replenish the solution to its original equilibrium of ammonium ions and bicarbonate ions preferably reused / to leach further waste material, will

The zinc content of the liquor will rise to a maximum solubility limit, after which the zinc will run out the solution is precipitated. Thus, before the subsequent first gasification stage at atmospheric pressure in this Wise precipitated zinc carbonate can be removed by filtration. However, rainfall at this stage is common contaminated with other components of the waste.

The invention is illustrated in more detail by the following examples.

example 1

There were crushed in a ball mill 11 kg scrap containing 10 wt .- ^ copper, residue 65 wt. -4 steel, 10 wt .- ^ iron, 15 wt. -4 aluminum. At the same time, 40 liters of an aerated solution containing 100 g of ammonium bicarbonate per liter and 2 g of copper per liter were circulated through the mill, after 8 hours the copper content of the solution had risen to 24.2 g of copper per liter, which resulted in complete extraction of the copper corresponds to the scrap.

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The solution was filtered to remove unreacted steel, iron and aluminum and then gassed with carbon dioxide until the copper concentration dropped 4.0 g of copper per liter. After filtering, washing and drying at 120 ° C, the precipitate contained 56.45 ^ copper. The theoretical amount for basic copper carbonate CuCO ₅ Cu (OH) ₂ would have been 57.5 $ copper.

Example 2

It was scrap with low copper content, containing 5 wt .- $ K _u pfer, 1 weight? " Brass, 15% by weight of aluminum, 60% by weight of iron, the remainder plastics and other non-metals, crushed and leached with an aerated solution containing 100 g / day of ammonium bicarbonate. Leaching was continued until the copper concentration in the solution reached 29 g / liter. The zinc concentration in the solution at that time was 1 g / liter resulting from the dissolution of the brass. The partially extracted scrap was then removed from the liquor by filtration, and carbon dioxide gas was introduced into the waste liquor at a total pressure of 1 atmosphere. After 6 hours the precipitate, which contained essentially all of the zinc and 60% of the copper in solution, was removed by filtration. Carbon dioxide gas was further introduced into the filtrate at a total pressure of 2 atmospheres. After 10 hours the copper concentration in the solution had dropped to 3 g / liter and the precipitate of copper carbonate was removed by filtration. This precipitate contained less than $ 0.1 zinc.

The pH-W _e rt the solution from the second Eingasen was

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then by gassing at atmospheric pressure and brought back to the original concentration with a small addition of ammonia. This regenerated solution was used to redissolve the mixed precipitation from the first gassing stage. Subject dissolving of the precipitate mixture was the solution again to Leaching a mixture of the partially extracted scrap from the previous step and again Used scrap.

Example 3

Zinc oxide was slurried in an aerated solution of ammonium bicarbonate (100 g per liter). Subject 8 hours the concentration of zinc in this solution was 6.4 g per liter. A practically complete recovery of the Zinc was obtained by precipitating the basic zinc carbonate formed with carbon dioxide. The zinc content the rainfall was $ 54.2 versus the theoretical Lot of $ 55 in basic zinc carbonate.

- claims

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Claims (5)

Claims 1. Process for the extraction of copper and / or zinc from waste such as scrap or these in small amounts Minerals containing quantities by leaching with an ammonia-containing solution, characterized in that that the solution used for leaching is an aerated aqueous solution of ammonium bicarbonate, e.g. 50 to 150 g per liter of ammonium bicarbonate and preferably contains a molar amount of carbon dioxide which is at least equal to the molar amount of ammonia, and the pH of which is preferably between 8.3 and 9.5. 2. The method according to claim 1, characterized in that copper and / or zinc from the aqueous liquor be isolated by the lye with carbon dioxide, preferably under superatmospheric pressure, brought into contact and Ilupfer and / or zinc carbonate precipitated out of solution. 3. The method according to claim 2, characterized in that copper and zinc from the waste at the same time be leached and the lye with carbon dioxide in 2 stages is brought into contact, whereby in the first stage carbon dioxide at relatively low pressure, e.g. atmospheric pressure, which is sufficient virtually all of the zinc and up to $ 60 of the copper to precipitate and in the second stage carbon dioxide at relatively high pressure, e.g. two atmospheres, is initiated, which is sufficient to precipitate most of the remaining copper. - 12 409830/0697 4. The method according to claim 2, characterized in that the ammonia concentration of the aqueous solution after recovery of the metal brought to the initial value and the solution leached again used by waste. 5. The method according to claim 3, characterized in that that after the recovery of the pure copper there is no impact from the lye the mixed precipitate of zinc and copper is redissolved in the lye Ammonia concentration set to the initial value the solution is used again to leach waste and this sequence is repeated zinc carbonate precipitated, e.g. by filtration, prior to the first introduction of carbon dioxide is isolated. 409830/0697