DE3329042A1 - METHOD FOR RECOVERY OF COLORED AND PRECIOUS METALS FROM CARBON-MATERIAL MATERIALS - Google Patents

Abstract

Process for the recovery of non ferrous and precious metals from carbon-containing materials particularly coking products by using a thermal process. A carbon-containing material having a certain content of non ferrous and/or precious metals is treated in a gasification reactor in the course of a substantially isothermal process by addition of a gasification agent produced from a fuel in a separated combustion chamber. Concerning its formulation (H2O/CO2/O2), the gasification agent is such that substantially isothermal ratios are obtained in the gasification reactor. The temperature regulation is effected by modifying the partial pressure ratio pO2/(pH2O + pCO2).

Description

Process for the recovery of non-ferrous and precious metals

of carbonaceous materials The invention is concerned with a process for the recovery of non-ferrous and precious metals from carbonaceous Materials, in particular made from coking products using thermal processes.

The above process is used in particular for the recovery of colored and precious metals from carbon-containing waste products such as cables or films. In this case, the metals can be recovered relatively easily if the carbon is burned or gasified. For such recovery are those processes are particularly suitable in which the melting temperature of the in metals contained in the carbonaceous materials and the softening point of the ash formed are not exceeded, so that the non-ferrous or precious metals ultimately exist in a dry ash. Otherwise caking can occur or sticking and thus a disadvantageous clogging of the reactors used come.

The process described above in which carbon is burned off but does not allow controlled temperature control. The one in the combustion process Occurring temperatures can rise so much, at least locally, that the melting temperatures the metals or the softening points of the ashes are exceeded. this leads to not only to loss of metal, but also to a significant disruption of the process. For the recovery of non-ferrous and precious metals from carbonaceous materials, In particular, old products, using thermal processes, is therefore gasification of carbon rather than combustion.

A water vapor (H20), carbon dioxide (CO2) is used as a gasification agent and gas mixture containing oxygen (02). Oxygen is preferably in the form used by atmospheric oxygen. In the case of the gasification of carbon, the following take place Reactions from: C + H20 O CO + H2 (1) C + CO2 r-- # 2 CO (2) C + 1/2 02- <CO (3) The gasification of carbon (C) with water vapor (H20) and with carbon dioxide (CO2) is an endothermic process, while gasification with oxygen (02) is exothermic expires. If HO or CO2 is consequently fed into the reactor, then it must be done at the same time so much oxygen are supplied that the exothermic reaction (3) the energy consumption for the endothermic reactions (1) and (2) as well as for the wall heat losses of the reactor covers.

When operating without oxygen, the reactor must be heated from the outside.

In general, the gasification of coal, coke or carbonaceous Waste products and the like. With the aim of producing a clean and combustible Gas carried out with the highest possible calorific value. As reactor types come z. B. the bulk reactor, the fluidized bed reactor, the reactor with circulating Fluidized bed and the fly ash reactor in question. For procedural reasons the gasification agent H2O, CO2 or ° 2 becomes relatively cold with one temperature fed to the reactor below about 5000C. However, at this low temperature only a little CO and H2 formed. The bulk must first be through the partial incineration of carbon with O2 to CO2 to the generally favorable reaction temperature be heated from about 800 to 9000C. Due to the partial combustion mentioned above of the carbon can then at least locally the melting point of the metals or the Softening point of the ashes are exceeded, which leads to disadvantageous clogging or gluing the reactor leads.

The above-mentioned procedures are essentially only about To gasify carbonaceous materials, especially coke products and the like. The recovery of non-ferrous and precious metals from these raw materials was not yet associated with such proceedings. This also applies, for example for the extraction of silver from photographic films, especially from X-ray films. The relevant prior art is described below.

DE-OS 27 48 051 relates to a method for treating photographic Films with a plastic base layer, a coating layer made of an adhesive and an organic layer containing silver Recovery of silver. Here the photographic film is in a very special way in one Wash tank treated with hot water in the presence of an enzyme with the aim of that Remove the coating from the adhesive as much as possible. The resulting washing liquid is filtered and the filter paper is roasted together with the residue to make gelatin and burn off other non-metallic materials and mainly metallic silver to leave behind. This known method is technically relatively complex and not to lead without loss. From DE-OS 27 48 051 it can also be seen that the most common method of recovering silver from photographic film should consist of burning the material or subjecting it to a combustion process, to then treat the remaining ash.

However, significant silver losses are said to occur here.

DE-OS 23 56 393 is also concerned with a method for Recovery of silver from photographic film. These films have a polyester film base which is provided with an undercoat on at least one surface a gelatin / silver halide layer is applied as a top layer. This Material is cut up. The pieces of film are then so long with a solvent treated until the underlayer is practically completely dissolved and containing the gelatin Cover layer is practically separated from the film base. The separated gelatin The silver it contains is then processed in a special way. It is advantageous to proceed in such a way that the silver is extracted from the gelatin-containing, material separated from the film pieces by flameless combustion of the ammonium nitrate mixed gelatinous material is recovered. This too procedure is in need of improvement with regard to a simple process management and in particular not very economical. In DE-OS 23 56 393 it is further pointed out, that generally silver from scrap film or used photographic film is recovered by burning the film as such and the silver-containing one Recovers component as ash or residue. Such a procedure should, however lead to undesirable air pollution with disadvantageous loss of silver.

The result is therefore the two publications discussed above infer that purely chemical work-up processes involving solution processes compared to burning the raw materials and processing the ashes on the Precious metal content are disadvantageous. Purely chemical separation processes are called particularly advantageous.

The invention was based on the object of a method for recovery of non-ferrous and precious metals from carbonaceous materials to propose that technically simple, trouble-free and with regard to the recyclable material to be recovered low loss and largely without environmental pollution as well as economically feasible is.

According to the invention this object is achieved in that a carbon-containing Material with non-ferrous and / or precious metal content in a gasification reactor at largely isothermal process control with the supply of one in a separate combustion chamber gasification agent generated from a fuel is gasified, wherein the gasification agent before entering the gasification reactor with regard to its composition (H2O / CO2 / O2) is adjusted in such a way that in the gasification reactor Set largely isothermal conditions, and the temperature control through The partial pressure ratio PO2 / (PH20 + Pco2) is changed.

Any carbonaceous material can be used for the purposes of the invention Use material with non-ferrous and / or precious metal content as the starting material, if it is basically the one already described above due to its chemical characteristics Gasification process permitted, with ultimately an ash product with greatly increased Metal content accrues. These can be cables or films, for example be used advantageously in lumpy or comminuted form. X-ray footage (Films and / or pictures) are due to the relatively high silver content in the foreground.

However, it has been shown that metal-containing or

in particular silver-containing plastic materials preferably initially a coking process to obtain a non-ferrous or precious metal-containing coke respectively.

coke-like product. The usual coking measures can be used here be seized. The starting materials are sealed in the absence of air, i. E.

heated in the form of so-called dry distillation. Various are running here Processes such as degassing, cracking etc. with the result that a product with comparatively high carbon content occurs in which the non-ferrous and / or precious metals are already enriched to a certain extent. Through this coking process metal contents of about 10 to 15% by weight can be set. As a A particularly advantageous special case of a coking process is in the context of Invention the pyrolysis process of importance, which is generally the chemical Decomposition of substances at high temperatures under Exclusion of air understands. Such a pyrolytic process plays a role in chemical engineering plays an important role, e.g. in the splitting of hydrocarbons for production pyrolytic graphite. If, however, within the scope of the invention of coking processes is spoken, this is to be understood as far as possible and generally relates to procedures where the original starting material is more or less in a coke or a coke-like product has been transferred. This is also the case with this term, for example To subordinate smoldering procedures. In itself, this is understood to mean dry distillation of natural fuels in the absence of air at temperatures of 450 to 6000C (Low temperature coking), in which all volatile components from the starting product escape with the formation of a coke-like product.

In the starting materials of the process according to the invention, in particular in the coke-like starting materials, there are the various colored and / or Precious metals. The term "non-ferrous metals" is a collective term for all (in themselves or in their alloys) heavy metals and their alloys except Iron and precious metals, i.e. for all heavy useful metals except iron count in particular copper, nickel and cobalt. To the precious metals are the elements Gold, silver, rhenium and the so-called.

Platinum metals (ruthenium, rhodium, palladium, osmium, iridium and Platinum) among others. In principle, only such non-ferrous and precious metals are from excluded from recovery by the process according to the invention, their melting temperature is below the temperature range in which gasification reactions are still possible. The lower limit of the gasification temperature is around 600 in practice up to 65000.

This area is easily made up of the following non-ferrous and precious metals exceeded: gold 10650C, nickel 14550C, cobalt 19030C, copper 1085 ° C, molybdenum 26220C, Palladium 15550C, Platinum 17690C, Rhenium 31800C, Rhodium 19600C, Ruthenium 25O00C, titanium 17000C, tungsten 18900C, silver 9600C, osmium 27000C and iridium 24430C.

For the purposes of the invention and for the production of the required therefor Gasification means any fuels can be used for which it is only it must be ensured that a gaseous gasification agent can be produced with them is, the water, carbon dioxide and oxygen in controllable and in particular in Contains such amounts that the gasifying agent introduced into the gasification reactor an isothermal process management via its partial pressure ratio Po2 / (PR2 o + makes possible. Thus, in the context of the invention, the term “fuel” is very extensive to understand, being a summary relationship for all solid, liquid or gaseous substances, either in natural form or derived from it by ennobling derived form, economical with atmospheric oxygen while releasing usable heat can be burned.

Main supplier of the calorific value, according to the benefit and economy of a fuel are carbon and hydrocarbon, where appropriate also hydrogen.

Natural fuels, for example, can be solid fuels, such as wood, peat, lignite, hard coal and anthracite, especially in refined Form can be used as briquetted coke. Appropriately, however liquid fuels such as crude oil, heating oil, coal tar oil, aromatic or aliphatic Hydrocarbons, such as gasoline and benzene, and especially their gaseous Fuels or fuel gases used.

"Combustion gases" comprehensively denote combustible technical gases (cf. Römpps Chemielexikon, 7th edition, Vol. 1, 1973, p. 421). Of particular advantage are natural gas, Coal gas, generator gas, various gaseous alkanes such as methane, ethane, Propane, butane and acetylene can be used. All of these gases can also be mixed can be used. It has been shown that natural gas is a particularly favorable one Process management is possible because the burned natural gas with an air factor of = 1.3 creates a gas mixture as a gasification agent with which the gasification conditions a coking product, in particular pyrolysis coke, at a temperature from about 700 to 9000C, in particular 750 to 8500C, are optimally maintained. It So it is shown that in the gas generator, as a rule, any fuel can be used that meets the requirements. Here it can can also be a pyrolysis gas or a gas that contains the exhaust gas represents the gasification reactor used according to the invention. The use of pyrolysis gas is associated with particular advantages within the scope of the invention. To recruitment The right gasification conditions in the gasification reactor will in particular include the oxygen content during the combustion, i.e. the air factor, set specifically. The one for the incineration Required oxygen is expediently introduced by atmospheric oxygen.

Should the gasifying agents produced during combustion in the gas generator have a higher temperature than required, water, in particular, is used for cooling injected into the gas leaving the gas generator. Is such a water injection not necessary, rather an increase in temperature is even sought, then the oxygen combustion stream supplied to the combustion chamber is elevated. In addition, there are other control options: this can be done before initiation of the gasification agent in the combustion reactor carbon dioxide and / or oxygen are fed. Accordingly, the person skilled in the art has a wide range of control options recognizable within the scope of the invention without it being necessary to go further in detail to explain.

The gas or gasifying agent leaving the gas generator needs not to be fed to the gasification reactor at a single point. Preferably However, this happens in the lower part of the gasification reactor.

In general, there is also the possibility, which is advantageous in individual cases may be to supply the gasification agent to the gasification reactor at inlets which are distributed over its height.

In principle, various options can be used for the method according to the invention known gasification reactors are used. So it can be the already act gasification reactors described in more detail above. A fixed bed reactor is preferred, which the carbonaceous material to be gasified in finely divided or lumpy Form is fed. A fluidized bed reactor or flue dust reactor can also can be used. However, it is important to ensure that due to the moving Material bed no or only small amounts of finely divided Material discharged from this above by the gas stream within the reactor and lead to environmental pollution.

If the gasification reactor is the gasification agent already with the desired Gasification temperature supplied, then combustion reactions no longer run or only to a minor extent. This means that the temperature of the gasifying agent as well as its composition with regard to its H2O, CO2 and O2 content is set that the occurring in the gasification and above in detail Exothermic and endothermic reactions already reproduced with regard to the heat balance roughly cancel.

In principle, the temperature in the gasification reactor is as high as possible to strive, since then the gasification processes proceed more favorably. In the individual case appropriate or required temperature depends on the melting point of the preferably used coking material contained metals. This temperature must be fallen short of sufficiently so that not due to melting processes and other chemical processes, losses of the desired metal occur. For in the event that a coking product containing silver is to be gasified, e.g. one obtained from X-ray films is preferably used in one area worked from about 700 to 9000C, very preferably in a range from 750 to 8500C. In this case, too, natural gas has proven to be a particularly cheap fuel proven for the production of the gasification agent.

In practice, the procedure is therefore such that initially due to from a purely professional point of view, a temperature that appears suitable, taking into account of the above technical statements is selected. In poll at this temperature the fuel used for the production will then be selected a gasification agent with the desired temperature makes possible. It will the gasification reactor initially in a certain preliminary phase, i.e. not under gasification conditions heated by the hot gasification agent.

The general procedure then is as follows: as soon as the desired Gasification temperature is reached, usually after half an hour to an hour, which also depends on the spatial dimensions of the gasification reactor used as well as the material to be gasified used; there is a kind of fine adjustment. If the temperature in the gasification reactor continues to rise, then a careful dosage to avoid a further increase in temperature or

Adjustment of the desired gasification temperature by the already specified spraying of water into the gasification agent immediately before introduction into the gasification reactor. Basically there is also the possibility of carbon dioxide instead of introducing steam.

Of course, the air factor could also be reduced. This would also change the temperature of the gasification agent, ultimately but in this way also an approximation or achievement of the desired isothermal process management be possible.

If, for example, the person skilled in the art has proceeded in the manner described above, then that means that with the same starting material in the form of the with the non-ferrous and / or precious metals loaded carbonaceous material, in particular Coking product, possibly still has to make certain fine adjustments in order to to allow the gasification to proceed in an optimal manner. The optimization consists in that caking or sticking or clogging of the reactor is excluded.

So this happens not only in a technically simple way, but also with considerable economic advantage. So it is from the point of view of economy also possible, the gases withdrawn from the gasification reactor, at least in part, to be fed back to the overall cycle via the gas generator. The inventive Process operated largely with little loss, i.e. losses of the desired precious or Non-ferrous metals are either absent or insignificant. In particular, the annoying local overheating excluded, which the undesirable phenomena, such as cause sticking and caking. In individual cases, however, it is necessary that the maximum temperature of the gasification process is not at the melting point of the metals is oriented, but the softening point of the ashes are taken into account and is not reached or exceeded.

The process product obtained according to the invention, which as a rule has a metal content of about 50 to 80 wt .-%, can then then again in simple and almost trouble-free process management, the usual melting-out processes, e.g. in a crucible or melting furnace. Such devices are known in the art. It can be shaft furnaces, hearth furnaces, crucible furnaces as well as drum and rocking ovens. This list goes without saying not completely, but rather other devices are also conceivable in which the desired non-ferrous or precious metals in the context of a kind of melt cleaning freed from unwanted accompanying materials, in particular the ash components will.

On the basis of the teaching according to the invention given, the person skilled in the art does not further possible that to achieve desired goals in practice. Further information is not required. Rather, those skilled in the art will recognize that the invention can also be subjected to various modifications without to leave their framework. For example, the heating process can be thereby accelerate that the gasification reactor provided with external heating devices is that additionally a temperature control during the course of the gasification phenomena make possible.

A comprehensive list of these modification options appears not necessary and, moreover, would also go to the limit, as it would be for the expert no additional necessary indications for the realization of the essential idea the invention would be given.

The invention is based on a drawing and a Example will be explained in more detail.

The figure shows an advantageous embodiment of a device reproduced, with which the method according to the invention can be carried out in practice leaves.

In the figure, a gas generator 1 and a reactor 20 are shown. A fuel, e.g. natural gas, reaches the preburner via a fuel supply 2 4, to which air is supplied as an oxygen supplier via a supply line 3. By doing Preburner 4 are already running certain combustion processes, which are in the following Main combustion chamber 5 to be completed. The main combustion chamber 5 leaves the gaseous and, if possible, the gasification agent already set to the desired temperature via line 6, which supplies the gasification reactor 20 with the gasification agent. if it is necessary, water is added to the gasifying agent via line 7 fluid or supplied in vapor form to target the composition of the gasification agent and to change with lowering of the temperature. That introduced into the gasification reactor 20 Gasification agent then occurs via a grate 8 in the colored or Carbonaceous material 9 containing noble metals, in particular coking product. This material 9 is in the form of a fixed bed in the gasification reactor 20. The ash-shaped material, which has largely been subjected to the gasification process, occurs Via the grate 8 it enters a funnel 10 and then falls into a collecting container 11. This material usually has a metal content of up to 90%. The upper part of the gasification reactor 20 leaves a gaseous product or exhaust gas at the outlet 12. This gaseous product can, but this is not shown in the drawing, are at least partially fed back to the gas generator 1.

The material 9 is preferably fed continuously to the gasification reactor 20 supplied in such amounts that the isothermal process is practically undisturbed remain.

The same also applies to the method according to the invention in general.

The end product obtained in the manner described above with strong A higher metal content can then be achieved much better, e.g. according to the known metallurgical Process melt cleaning processes, including conceivable facilities have been given above.

Example The starting material was a pyrolysis coke with a silver content of about 5.72% by weight. This material was run in a pilot facility similar to that above described Embodiment of a device in principle is carried out. The duration of the experiment was 5 hours with gas consumption from 15 mN3. Natural gas was used as fuel. The combustion of natural gas took place under the following conditions: fuel Lmin - 8.11 mN3 / mN3 (air factor) = 1.2 @ air = 29.2 mN3 / h The composition of the gasification agent was: H2O 15.76 Vol.% C02 8.17 Vol.% O2 3.16 Vol.% N2 72.91 Vol.% A pyrolysis coke was used in an amount of 1285 g with the above silver content. From the inserted Material was recovered 141 g of ash.

The ash obtained as process products in an amount of 142.1 g, which made up 11.1% by weight of the starting product, contained about 75% silver. One Further processing or enrichment of the silver was carried out in a crucible furnace made, which resulted in almost 100% silver.

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Claims (14)

Claims 1. Process for the recovery of non-ferrous and precious metals from carbonaceous materials, especially from coking products under Use of thermal processes, which means that a carbonaceous material with nonferrous and / or precious metal content in a gasification reactor in a largely isothermal process with the supply of a separated in a get Combustion chamber is gasified from a fuel generated gasification agent, wherein the gasification agent before entering the gasification reactor with respect to its Composition (H20 / C02 / 02) is adjusted so that in the gasification reactor Set largely isothermal conditions, and the temperature control through The partial pressure ratio P% / (PH o + PCO,) is changed. 2. The method according to claim 1, characterized in that the controller the partial pressure ratio POz / (PH + PCO by changing the mass flow the combustion air supplied to the separate combustion chamber and the water content is controlled in the gasification agent. 3. The method according to claim 1 or 2, characterized in that for Production of the gasification agent containing a gaseous hydrocarbon Fuel is used. 4. The method according to claim 3, characterized in that natural gas, Methane, ethane, propane and / or butane can be used as the hydrocarbon. 5. The method according to any one of claims 1 to 3, characterized in, that process gases from other process engineering systems, in particular from pyrolysis systems, be used. 6. The method according to any one of claims 1 to 3, characterized in that that the exhaust gas leaving the gasification reactor at least partially as fuel is used. 7. The method according to any one of claims 1 to 4, characterized in that that coking products are used as the carbonaceous material. 8. The method according to claim 7, characterized in that the coking product is obtained by pyrolysis. 9. The method according to claim 6 or 7, characterized in that a Coking product with silver content is used. 10. The method according to claim 8 or 9, characterized in that the coking product is obtained from X-ray film material. 11. The method according to any one of claims 1 to 10, characterized in, that a fixed bed reactor is used as the gasification reactor. 12. The method according to claim 11, characterized in that a carbon-containing Material is used in lump form. 13. The method according to any one of claims 1 to 12, characterized in that that the process is carried out continuously. 14. The method according to any one of claims 1 to 13, characterized in, that the non-ferrous or precious metals from the process product by means of the melting process can be obtained in pure form.