SK132497A3 - Process for the separation of copper and heavy metals from incinerated garbage residue and slag - Google Patents

Abstract

In a process for the separation of copper and heavy metals from incinerated garbage residue and slag, the residue and slag from garbage incineration or pyrolysis is heated to over 650 DEG C under reducing conditions together with substances containing chlorine or chlorides, such as flue gas cleaning residues, CaCl2 from the soda production, cooking salt, organic solvents or electroplating sludge containing chlorine, whereupon Cu-chlorides and volatile heavy metal chlorides, such as PbCl2 or ZnCl2, are drawn off in the gas phase.

Description

Technical field

The invention relates to a method for separating copper and heavy metals from waste incineration debris and debris.

BACKGROUND OF THE INVENTION

In conventional waste incineration plants as well as waste pyrolysis plants, residues are generated in the form of pyrolysis residues or residues, respectively. debris from waste incineration. As a rule, such slags are relatively acidic and, depending on the origin of the waste, and especially when industrial waste is used, such slags are very heavily contaminated with heavy metals. Immediate recovery of such debris without more or less costly cleaning is only possible with high-tech machinery.

SUMMARY OF THE INVENTION

The invention now aims to make the residues from the incineration of heavy metals containing waste suitable for further processing, in which, for example, in connection with steel slags, hydraulic binders, environmentally friendly or other valuable materials can be recovered. In particular, such a slag, which is not immediately suitable for metallurgical processes, respectively. such residues are to be processed into a synthetic blast furnace slag with hydraulic properties as well as a high-value, carbon-saturated iron alloy. In order to solve this problem, the method according to the invention essentially consists in that the waste and debris from the incineration of waste, respectively. from pyrolysis together with substances containing chlorine or chloride, such as flue gas cleaning residue, CaCl ₂ from soda production, table salt, chlorine containing organic solvents or galvanizing sludge, are heated under reducing conditions above 650 ° C, after which Cu-chlorides and volatile chlorides of heavy metals such as e.g. PbCl ₂ or ZnCl ₂ is withdrawn in the gas phase. By the residues and debris from the incineration of waste, respectively. the pyrolysis residues are roasted together with chlorine-containing substances, respectively. chloride, and in this roasting, the reduction conditions are maintained, the heavy metals are separated in the form of volatile chlorides and discharged through the gas phase. This gas phase can be purified in a conventional manner, whereby copper, chloride, lead chloride and zinc chloride can be quantitatively trapped in the filters. At the same time, such a process makes it possible to process other difficult-to-dispose products, such as chlorine-containing organic solvents, as well as flue gas purification residues or calcium chloride from soda production, whereby a large number of problem substances can be disposed of simultaneously. In principle, said heavy metal chlorides have relatively low vapor pressure at low temperatures. The vapor pressures of the relevant heavy metal chlorides at 600 ° C show the following values:

component

Vapor pressure (bar)

CuCl ₂ , (CuCl) ₂

PbCl ₂

ZnCl ₂

0,005

0.07

0.1

In order to achieve safe gasification at relatively low temperatures, a corresponding reduction of the respective partial pressure must be carried out, for example using a purge gas, or it must be operated under at least a partial vacuum. The process according to the invention is preferably carried out by using purging gases, in particular flue gases, at temperatures between 650 ° C and 1400 ° C to remove the volatile chlorides, which results in sufficient gasification of the heavy metal chlorides. Alternatively or in addition to the use of such a purge gas, it can also be operated in a partially evacuated shaft furnace, or a purge gas at vacuum can be used. At a pressure of 1 bar and without using a purge gas, the chlorination would have to be carried out at a temperature of about 1400 ° C, i. at the melting point.

.Opatrením 'according to the invention ensures that * ^1' 'sufficiently large depletion of the heavy metals is obtained in the conventional shaft furnace with the exhaust gas as the purge gas has a temperature of 850 ° C, while preferably proceeds by heating the residues and slags from waste incineration to temperatures of about 850 ° C, it is carried out in a shaft furnace or a cylindrical rotary kiln.

The recovery of the heavy metals from the gas phase can be carried out in a particularly simple manner by passing the gas phase containing the volatile heavy metal chlorides through the filter, and by filtering the dust containing the heavy metal chlorides dissolved in water and / or cementing Fe-scrap, after which the heavy metal chlorides are extracted and / or the heavy metals are separated by fractionation electrolysis and / or fractionated distillation. In scrap metal cementation, heavy metal oxides are reduced to form iron chloride. At partial pressures, preferably fractionation electrolysis can be separated separately with high purity by copper, tin, nickel and other metals.

In order to ensure adequate and at the same time maintain the reduction conditions, the heating is carried out in a shaft furnace in countercurrent with the flue gas.

Particularly economically efficient treatment of the depleted residues and debris from waste incineration, respectively. pyrolysis is achieved when, as in the preferred embodiment, the solid residues are heated in an amount of 10 to 40 wt. %, preferably about 20 wt. %, mixed with liquid steel slag or calcium saliva to a mixed slag, the remaining, evaporating heavy metals such as Pb and Zn separated from the gas phase, and optionally dissolved chlorides, such as e.g. CaCl ₂ is oxidized with the release of Cl ₂ , and the mixed slag is over a swirling Fe bath with a C content of between 3 and 4 wt. % reduces. Since the heated residues react with an acid, the strongly basic steel slag at least partially neutralizes when mixed with the steel slag, while at the same time the viscosity drops. By mixing and neutralizing heat, any remaining heavy metals can be safely brought to evaporation. At the same time, iron bath sediments from the steel slag! and preferably the swirling Fe-bath is subjected to a fractionation reduction to separate the ferrochromium alloy. This swirling Fe-bath must be maintained at a desired carbon content of between 3 and 4 wt. % in order to ensure that the desired reduction occurs, in total 1 t of synthetic blast furnace slag and 0.9 t of pig iron can be obtained, for example, from about 0.4 t total of roasted slag and 1.6 t of steel slag. To ensure that material is created,

- 5 to be used as an additive in cement, the chlorides must first be removed.

Particularly advantageously, the method of reducing roasting of waste incineration residues and slags can thus be combined with the corresponding method for producing synthetic blast furnace slags, since the CO generated by the desired carbon contents in the iron bath can be used particularly well for energy purposes. Preferably, for this purpose, the CO formed in the reduction of the slag mixture in the dissolved carbon in the Fe-bath is used for further combustion and heating of the mixed slag resp. residues.

In order to further improve the quality of the synthetic blast furnace slag and to be able to produce particularly good materials such as cement additives or cement directly, it is preferred to proceed. by adding bauxite, respectively, to the liquid mixed slag. N, O-J.

As mentioned above, the desired partial pressures of the volatile chlorides are set either by the corresponding amounts of purge gas or by using a pressure lower than atmospheric.

The invention is explained in more detail below by way of example.

DETAILED DESCRIPTION OF THE INVENTION

The incinerator slag (waste slag) with the following composition was used:

component Share ( SiO ₂ 43 CaO 13 ^^ 2θ3 8.5 Fe ₂ ° 3 10 MgO 1.5 Na ₂ O 3.5 Sat ₃ 1 tío ₂ 1.5 Cu 0.4 Ni 0.04 Cr 0.15 Zn 0.35 Pb Q, 15

The rest of the analysis is unburned residues and scrap.

Such waste slag, together with 10% CaCl ₂ (3.6% Ca + 6.4% Cl), was placed in a shaft furnace and heated in an oxygen-deficient (countercurrent) manner. The flue gas temperature from the shaft furnace was 850 ° C. Roasted, molten waste slag showed the following analysis:

component

Percentage (%)

Si ° ₂

CaO

Α1ζθ3 ^Fe 2 ° 3

MgO 2 Na ₂ O 3 Sat ₃ 0.5 tío ₂ 1.5 Cu 0.08 Ni 0.02 Cr 0.2 Zn 0.06 Pb 0.04

The roasted waste slag was mixed with 80 slags of the following composition in the liquid state:

a steel

component

Percentage of steel

SiO ₂ and i ₂ o

CaO

MgO

FeO

WITH

P

Cr

0.05

0.5

The mixed slag consisted of the following:

component

Share (%) steel

Si ° ₂

CaO ai ₂ o

FeO

MgO

Na ₂ O

S0 ₃ tio ₂ cu

Ni cr

3.5

0.6

0.15

0.3

0,016

0,004

0.9

During the mixing process, Zn and Pb evaporate virtually quantitatively and can be recovered from the flue gas.

This waste slag in the OBM converter was reduced over a swirling iron in an iron bath bath

By means of carbon reduction, heat dissolution and waste heat loss, the combustion of the CO formed in the upper part of the converter in the gas phase is very economically fed into the process.

The reduced slag had the following composition:

component Share ( ^si0 2 35 CaO 52 Al2O3 5 MgO 5 Na ₂ O 1 Sat ₃ 0.25 tío ₂ 0.5 Cr 0.03

The heavy metals Cu and Ni could no longer be detected in the reduced slag by X-ray fluorescence analysis (limit of detection about 100 ppm).

Water-granulated slag has proven to be a well hydraulically active component of mixed cement. About 10% bauxite (Al ₂ O ₃ ) was added to the liquid slag melt to increase the initial strength of the mixed cement.

The obtained regus (pig iron) had the following composition:

component

Cu

Ni

Cr

C

fe

Percentage (%)

0.05

0.01

2.6

3.8 rest

The process was conducted in such a way that the proportion of carbon in the iron bath was always in the range between 3 and 4 wt. %. The pig iron thus obtained represents a high-value feedstock for the steel industry. Alternatively, a carbon-free, highly enriched ferro-chromium alloy can be obtained by fractionated reduction.

Claims (10)

Method for separating copper and heavy metals from waste incineration debris and debris, characterized in that the waste incineration debris and debris, respectively. The pyrolysis, together with chlorine or chloride containing substances such as flue gas scrubbing residue, CaCl ₂ from soda production, table salt, chlorine containing organic solvents or galvanizing sludge, is heated under reducing conditions above 650 ° C, after which Cu -chlorides and volatile chlorides of heavy metals, such as e.g. PbCl ₂ or ZnCl ₂ is withdrawn in the gas phase. Second The method of claim 1, v y z n by that when temperatures between 650 ° C and 1400 ’C will be used purge gases, in particular hot flue gas, to remove volatile chlorides. Method according to claim 1 or 2, characterized in that the gas phase containing the volatile heavy metal chlorides is passed through the filter, and that the filter dust containing the heavy metal chlorides is dissolved in water and / or cemented with Fe scrap, after which the heavy metal chlorides are extracted and / or the heavy metals are separated by fractionation electrolysis and / or fractionated distillation. Method according to claim 1, 2 or 3, characterized in that the heating is carried out in the shaft furnace in countercurrent with the flue gas. A process according to any one of claims 1 to 4, characterized in that the heated solid residues are in an amount of from 10 to 40 wt. %, preferably about 20 wt. %, mixed with liquid steel f slag or lime saliva to the mixed slag, the remaining, evaporating heavy metals, such as Pb and Zn, are separated from the gas phase and optionally dissolved chlorides, such as e.g. CaCl ₂ is oxidized to release Cl ₂ , and the mixed slag is reduced over a swirling Fe bath with a C content between 3 and 4 wt%. Method according to any one of claims 1 to 5, characterized in that the swirling Fe bath is subjected to a fractionation reduction to b r separation of ferro-chromium alloy. c < Method according to any one of claims 1 to 6, characterized in that the heating of the residues to a temperature of about 850 ° C is carried out in a shaft furnace or in a cylindrical rotary kiln. Process according to any one of claims 1 to 7, characterized in that the CO formed during the reduction of the slag mixture in the carbon-dissolved Fe-bath is used for further combustion and heating of the mixed slag or slag. residues .. Method according to any one of claims 1 to 8, characterized in that bauxite and / or bauxite are added to the liquid mixed slag. A1 ₂ O ₃ . The method of any one of claims 1 to 9, wherein the heating is carried out at a pressure below atmospheric.