AU661395B2

AU661395B2 - Process for recycling solids, powders and sludges contaminated with mercury

Info

Publication number: AU661395B2
Application number: AU39502/93A
Authority: AU
Inventors: Jean-Francois Equey; Jozef Hanulik
Original assignee: Recytec SA
Current assignee: Recytec SA
Priority date: 1992-04-01
Filing date: 1993-03-31
Publication date: 1995-07-20
Anticipated expiration: 2013-03-31
Also published as: JPH07500380A; CA2110400A1; WO1993020593A1; NO934344L; AU3950293A; EP0587867A1; FI935368A0; FI935368A; NO934344D0

Description

b/ OPI DATE 08/11/93 APPLN. ID 39502/93 lIIl f iili111111111111111 m AOJP DATE 13/01/P4 PCT NUMBER PCT/EP9,3/00793 1111111111Iliiii ~i1111111 11111111ll1l1l11l1 AU9339502

)IE

(51) Internationale Patentklassiikation 5 (11) Internationale Veriiffentlichungsnummer: WO 93/20593 H01IM 6/52, C22B 43/00 Al (43) Irnternationales Verbtientlichungsdatum: 14. Oktober 1993 (14.10.93) (21) Internationales Aktenzeichen: PCT/EP93/00793 (74) Anwalt: SCHULZ, Jean-Alain; Bugnion Postfach 375, CH-1211I Genf 12 (CH).

(22) Internationales Anmelddlatumn: 3 1. Mirz 1993 (31.03.93) (81) Bestimmunigsstaaten: AT, AU, BB, BG, BR, CA, CH, CZ, Priori taitsdaten: DE, DK, ES, Fl, GB, RU, JP, KP, KR, LK, LU, MG, 1064/92-8 1. April 1992 (01.04.92) CR MN, MW, NL, NO, NZ, PL, RO, RU, SD, SE, SK, UA, 1148/92-3 8. April 1992 (08.04.92) CR US, europffisches Patent (AT, BE, CR, DE, DK, ES, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE), OAPI Patent (B3F, BJ, CF, CG, CI, CM, GA, GN, ML, MR, NE, SN, (71) Anmelder (ir alle Besdimtnungsstaatcn ausser US); RECY- TD, TG).

TEC S.A. [CR/CH]; c/o Orfigest 22, rue du Puits- Godet, CH-2000 Neucluitel (CR).

Verbffentlicht (72) Erfinder; und Alit internationalemn Rechcrchenbericht.

Erfinder/Anmelder (nurfifr US) R ANULIK, Jozef [CR/ Vor Ablazuf der flir 4ndeningen der Ansprfiche zugelasse- CR]; Pilatusstrasse 7, CH-8032 Z~irich EQUEY, nen Fris. Ver!dffendichiung ivird u'iederlialt frils Ainderun- Jean-Franqois [CR/CR]; 65, rue de Lausanne, CH-1028 geti elntreffen.

Preverenges (CR).W 661395 (54)Title: PROCESS FOR RECYCLING SOLIDS, POWDERS AND SLUDGES CONTAMINATED WITH MERCURY (54) Bezeichnung: VERFAHREN ZUR REZYKLIERUNG VON DURCH QUECKSILBER KONTAMINIERTE FEST- STOFFE, PULVER UND SCHLAiMME (57) Abstract When a mixture of spent electric batteries is treated by pyrolysis, a pyrolysis slag is obtained having at least a residual mercury content between 50 and 1500 ppm, according to the battery type, It does not seem possible to eliminate this residual content by simply modifying the parameters of this pyrolysis process. The residual content may however be lowered below 10 ppm by a second thermal treatment between 500 'c and 700 Preferably the material to be treated is crusched between the first pyrolysis and the second thermal treatment, and the second thermal treatment is carried out while air or nitrogen is blown through the material.

(57) Zusammenfassung Wenn emn Gemisch von ausgedienten elektrischen Gerfitebatterien durch Pyrolyse behandelt wird, entsteht eine Pyrolyseschlacke die meistens cinen Restgehalt an Quecksilber von 50 bis 1500 ppm, je nach Batterientyp, aufweist. Es erscheint nicht m6glich, durch Verflndern der Verfahrensparameter dieses einzigen Pyrolyseverfahrens, diesen Restgehalt zu entfernen. Durch eine zweite thermische Behandlung zwischen 500 *C und 700 'C kann jedoch der Restgehalt unter 10 ppm herabgesenkt werden.

Vorzugsweise wird das zu behandelnde Material zwischen der ersten Pyrolyse und der zweiten thermischen Behandlung zerkleineil, und die zweite thermische Behandlung unter Luftdurchfluss oder Stickstoffdurchflusb iuasgefdihrt.

WO 93/20593 PCT/EP93/00793 Process for the recycling of mercury-contaminated solids, powders and sludges The present invention relates to a process for the decontamination by pyrolysis of mercury-contaminated solids, powders and sludges.

The present invention is used in particular in a process for the recycling of a mixture of exhausted equipment batteries of any chemical composition, in which, in a first step, the unsorted mixture is pyrolyzed and then the pyrolysis slag is further processed.

EP-0-274 059 discloses a process for the recycling of such a mixture (and of assembled printed circuit boards and electronic components), in which according to the teaching of the patent a pyrolysis of the unsorted mixture is carried out at a temperature between 450°C and 650°C, then an electrolysis of the pyrolysis slag is carried out in a solution of tetrafluoroboric acid and salts thereof, and then a separation of the electrolysis products and removal of the products produced at the electrodes are carried out.

At these pyrolysis temperatures, plastic, starch, pigments and other organic components are carbonized without complex degradation products (in particular PCBs, dioxins) already being formed. The pyrolysis is preferably carried out in an inert or in a reducing atmosphere in order to avoid the risk of explosion and to prevent the metal oxidation. The volatile components are withdrawn from the furnace or distilled off. The pyrolysis gas products and vapor products such as water, carbon dioxide, carbon monoxide, hydrochloric acid, amonium chloride and, in particular, mercury are passed according to known technology through coolers, scrubbing columns and gas filter plants, in particular the mercury being condensed and recovered. It has been shown that in the case of conventional mercury concentrations in the starting material, from a few thousand to a few ten thousand ppm of by far the majority distill, but the o 8 remaining mercury in the pyrolysis slag is present at a i,

;I

I;:

r; :i I -2mean concentration of 50 to 500 ppm.

Supplementary to this teaching according to the patent, it is possible to shred and wash the pyrolysis slag in order thus to reduce the content of salts, such as KCl, ZnCI 2 before the pyrolysis slag is conducted to the electrolysis bath. It is equally possible to separate the washed or unwashed shredded pyrolysis slag by a screen having a mesh width of approximately 2 nmm into metallic coarse components and powder and equally to separate off the iron pieces by an electromagnet according to known technology. The electrolysis can then be carried out separately for the powder component and for the coarse components: this is expedient, because the coarse components contain a high proportion of metal and the electrolysis can be carried out simply and with a low energy consumption, while the electrolysis of the powder proceeds lengthily, expensively and with a high energy cons=iption. In an industrial battery recycling plant which uses this process, the capital costs and operating costs for the electrolysis of the powder are approximately five times as high as those for the electrolysis of the coarse components. It would therefore be desirable for cost reduction to further process the powder portion otherwise than by electrolysis.

Studies of the unwashed powder present after the pyrolysis show, for example, the 9611 owing composition: approximately 25-40% MnO., 15 to 25% graphite, approximately 20-30% Zn and ZnO, approximately 5 to 10% Fe and FeO x approximately 5 to 7% water-soluble salts and finally approximately 50 to 500 ppm Hg a approximately 200 to 3000 ppm Cd or CdO, depending on origin. This high mercury contamination makes impossible a direct sale of the powder as a by-product to the major metal industries, because these generally only accept MnO-Zn powder having mercury contamination below the 10 ppm limit.

On the other hand, in the above-described process, the residual content of mercury of the pyrolysis slag is carried along during the scrubbing and screening Sprocess steps (and only separated out during the 3.

3 electrolysis), so that these have to be carried out with special precautionary measures. It would therefore be desirable in the above-described process to reduce the mercury level beneath the generally accepted 10 ppm limit at the earliest possible stage.

EP-A-0-075 978 discloses a process for the recovery of metals from scrap of nickel-cadmium storage batteries, in which the organic constituents are removed by pyrolysis in an inert gas/oxygen atmosphere, then at high temperature the cadmium is distilled off and condensed and a mixture of nickel and iron scrap is obtained as a residue. The problem of mercury contamination when the mercury-containing batteries are present in the starting mixture is not recognized or covered by EP-A-0 075 978. It is not obvious from this patent whether the mercury distills off with the cadmium or is retained in the Ni-Fe scrap.

EP-A-0 158 627 describes a process for the recovery of ferromanganese from discharged zinc-carbonmanganese oxide batteries. According to this process, the battery scrap, together with carbon and iron is fused in a reduction vessel at approximately 1400 0 C to 1600 0 C, i volatilized zinc being recondensed on the one hand, and manganese recovered as ferromanganese. In small bat- teries, the mercury content can be up to 3% by weight.

For its removal, the batteries are comminuted and the scrap, before the reducing fusion, being- heated to temperatures around approximately 600°, similarly to the,.

pyrolysis process step described in EP-A-0 274 059. The mercury residue, not specified in EP-A-0 158 627, in the pyrolysis slag after this first process step should therefore be in the same range of values.

It has been shown that the residual values of the mercury contamination of the powder portion of the pyrolysis slag of battery mixtures of conventional type, as were on the market in earlier years, is on average around 150 ppm. In mixtures which are predominantly com- S' N posed of alkali batteries of the types which are newly on 1- the market, this residual value is up to 1500 ppm Hg.

L ZJ p.- 3 ja 4 It has now been shown that it is not possible to reduce these residual values in a single pyrolysis, either by increasing the pyrolysis temperature within the industrially acceptable temperature range, by prolonging the pyrolysis time, by blowing through N 2 gas for additional entrainment of the mercury vapors, or by other.obvious measures.

It is an object of the present invention to overcome or substantially ameliorate the above disadvantages.

There is disclosed herein a process for the decontamination by pyrolysis of mercurycontaminated solids, powders and sludges, in which the contaminated material is subjected to a first pyrolysis in a heated furnace, and wherein the already-pyrolyzed material is subjected to a second thermal treatment by heat, the Hg and/or the Hg compounds being evaporated out of the treatment furnace and being transported away out of the furnace by the gas stream produced in the treatment furnace or fed to the treatment furnace and to an exhaust gas purification system.

The second thermal treatment according to the invention of the pyrolyzed and chopped material can be carried out either on the entire starting material or else only on a part thereof, preferably the fine portion or powder obtained by screening.

It has surprisingly ensued that chopping (shredding) the starting material and a subsequent single pyrolysis only seldom achieves a mercury residue below 100 ppm, whatever pyrolysis parameters are selected, If, in contrast, after a first pyrolysis step the pyrolysis slag is subjected to a second thermal treatment, mercury residual values around ppm are systematically achieved, usually beneath this. The possibly coarse or clumped pyrolysis slag can, as required, be appropriately comminuted and/or loosened, and by adjusting the process parameters (time, temperature, stirring, gas feed etc) in each case according to composition and type of the material to be treated, those skilled in the art can usually reduce the mercury residue to 0.9 to 6 ppm by the second thermal treatment according to the invention.

According to the invefition, the following materials can be subjected to the second thermal treatment: all of the pyrolysis slag coarsely shredded, unwashed Ci ti f t i t it C

C

*r I* S G:\WPUER\LLW1T00546:TCW

I

all of the pyrolysis slag coarsely shredded, washed all of the pyrolysis slag coarsely shredded and then finer comminuted, unwashed all of the pyrolysis slag coarsely shredded and then finer comminuted, washed. After coarse shredding and screening, the finer portion unwashed, not milled the finer portion washed, not milled (sludge) the finer portion unwashed, milled the finer portion washed and milled (sludge).

The coarser portion can, after screening, be likewise thermally treated.

However, the application of the process according to the invention is not restricted to the above-listed mercury-contaminated solids powders and sludges from exhausted batteries, but it can also be applied to other mercury-containing industrial wastes, for example Hgamalgam-containing raw materials and intermediate products which have a fabrication defect.

The second thermal treatment can be carried out either under a reducing atmosphere or under an oxidative (air/0 2 atmosphere. f If the second thermal treatment is carried out under an oxygen-containing atmosphere, the following advantageous aspects result: a) the combination of heating and oxidation by air in the second thermal treatment oxidizes the combustible or oxidizable mixture components, such as graphite, Zn, Cd, amalgams and a binding with the mercury is prevented, as a result of which the mercury can more easily be removed by suction.

b) the combustion of the graphite to give CO 2 effects an additional internal flushing of the material in the furnace and facilitates the transport away of the Hg.

c) the treated material is freed from graphite 4AI and carbon residues.

d) the oxidation reaction and combustion reaction -6are entirely exothermic, which contributes to the heating and reduces the consumption of supplied energy.

If the material which is to be treated by the second thermal process step contains a significant proportion of higher manganese oxides (MnO 2 Mn 3

O

4 or Mn 2 0 3 oxidative conditions prevail in the treated mass, even without oxygen-containing gas supply. As a result, carbon residues and likewise Cd and Zn are at least partially oxidized. The CO, formed contributes to the removal of the Hg and CdO is much less volatile than metallic Cd so that less Cd distills over. Even without oxygen supply, local overtemperatures with respect the adjusted furnace setpoint have been detected in the treated mass, which is possibly due to non-homogeneous distributions of MnO 2 and C and local exothermic reactions. Blowing through N 2 gas instead of air can reduce such overtemperatures from approximately 100 to 150 0 C to about 50 0 C. Although these overtemperatures have no direct influence on the removal of mercury achieved in the final result, they should be avoided if it is undesirable that Cd distills off together with the mercury vapor and condenses in the cooler. If it is desired to avoid Cd distilling off, the temperature of the treated mass should as far as possible not exceed or hardly exceed 700 0 C. Since, on the other hand, all those substances which can lead to the PCB or dioxin formation have already been taken off in the first pyrolysis, the second pyrolysis can take place at higher temperatures than the first (which is conventionally carried out at 500°C to 550 0 The second thermal treatment is preferably carried out at temperatures around or above 600 0

C

for optimal removal of mercury. Since, when a second thermal treatment is used, it no longer matters that in the first pyrolysis the first removal of mercury be as complete as possible, this first pyrolysis can now be carried out at somewhat lower temperatures (400 0 C to 500*C) instead of the otherwise used 500 0 C to 550 0

C.

If, in contrast, it is desired to distill off the i e cadmium, it is advisable to create reductive conditions 7 in the treated mass and to distill off cadmium vapors at elevated temperature: this can, for example, be achieved by adding carbon, preferably in graphite form, to the material before the beginning of the second thermal treatment (possibly even before the first pyrolysis), which carbon in a first phase of the treatment in which the furnace temperature is held below 700'C, which reacts the manganese oxides, after which the furnace temperature is increased above the boiling point (750°C) of the cadmium, for the volatilization thereof.

The present invention is now described in more detail with reference to a preferred embodiment and particular examples, drawings and results of measurement.

Figure la shows a schematic course of a preferred process according to the present invention.

Figure lb shows the temperature-time course in the furnace and at various measurement points P in the mass of the treated powder (P1 P2 P3 P4 x) with progressive heating of the furnace and without gas supply.

The Figures 2a and 2b show the temperature-time course in the furnace and at the measurement points P1-P5 at a constant furnace temperature of 600 0 C, in each case with air and nitrogen through-flow.

The Figures 3a and 3b show the temperature-time course in the furnace and at the measurement points P1-P5 at a constant furnace temperature of 5001C, in each case 20 with air and nitrogen through-flow.

In Figure la, the box labeled with the designation number 1 symbolizes the pyrolysis furnace. The battery mixture symbolized by 0 is placed into this. The first e pyrolysis which takes place in the furnace 1 is preferably carried out at a temperature tt between 450°C-700°C. In this case, there escape, inter alia, the organic substances, water, oils and the majority of the mercury. In order to avoid explosive gas mixtures in the furnace, nitrogen is conventionally blown through the furnace. This nitrogen simultaneously serves as a transport medium for the mercury vapors. All of the substances are removed by suction from the furnace and passed (44, t t c 4 4' I, C~ S/ nr (GAWPUSER\LBTr ')QS461TCW -8through an exhaust gas filtration plant 3. The mercury removed by suction will be produced here. The exhaust gas filtration plant is described in more detail in EPA-0 274 059 which is herewith incorporated into the description. The pyrolysis slag 2 is removed from the furnace 1 and fed to a shredder 4. The comminuted pyrolysis slag is then washed at 5. In this case, a majority of the water-soluble salts are washed out. The water-soluble salts 6 can subsequently be removed from the water by known processes, for example crystllization. The shredded and washed pyrolysis slag is then separated at 7 by a screen into coarse components 8 and fine components or powder 10. The coarse components are composed essentially of Zn, Cu, Ni and graphite residues.

Iron portions, which can likewise be present, can be removed by a magnet 14. The remaining coarse components are placed into an electrolysis bath and here separated electrolytica ly. The metals produced at the cathode are removed and sold to metal industry enterprises (arrow 13).

The fine components 10 screened out are not fed to a powder electrolysis plant, but are fed to a second pyrolysis. This can take place either in the alreadymentioned batch furnace 1 or in a second continuous furnace 11 having a conveyor screw. Since all organic substances have now been carbonized in the first pyrolysis, the second pyrolysis can take place at higher temperatures, 600 0 C to 700 0 C. Depending on the starting material 10, either air L or nitrogen or no gas at all can be blown through the furnace 11). The irre vigorous the spontaneous gas development in the second pyrolysis is, the lower the amount of air which is required as a transport medium for the mercury transport is.

Depending on the starting material, the second thermal treatment can also be carried out in the temperature range 500 0 -600°C.

The volatile portions produced in the second pyrolysis are in turn fed to an exhaust gas filter plant, 9 which is the same as or similar to that of the exhaust gas filter plant 3. The mercury removed from th" exhaust gas purification system 3 or 12 is supplied to reuse.

By way of example, the following results are given in the second thermal treatment according to the invention: Example 1 A laboratory furnace is adjusted to a setpoint temperature (6000C or 7000C). Powder substances from a first pyrolysis are placed in a crucible (layer thickness 4 cm) and put into the furnace. The experiment proceeds statically, that is without stirring and without gas through-flow. Substances tested: powder from a mixed battery stock; Hg residual content: 150 ppm powder from alkali batteries; Hg residual content: 1500 ppm S Hg-Zn amalga, 'Tranules in KOH-containing starch gel; Hg r sidual content: 14,000 ppm.

26 In the statement of the residence times in the furnace, 45 minutes are allowed for the temperature adaptation of the samples. The results are reproduced in Table 1. (W washed; NW not washed, M milled; NM not milled). From this it can be seen that mercury can easily be removed from already-pyrolyzed powder from a stock of mixed types of batteries, but that mercury can only be removed from powder originating from alkali batteries at a higher temperature and residence time under static conditions.

Example 2 Temperature variations in the treated mass.

The samples (1.7 kg) are placed into a laboratory crucible and form a layer of 8 cm thickness. Gas liters per minute) can flow through the mass through a perforated tube. lihe temperatures in the samples are measured locally at a plurality of positions by Ni-Cr probes.

Figure lb shows a temperature course without gas supply. The furnace is progressively heated and reaches A~ I 10 600 0 C in the course of 5 hours. It is seen that the powder temperature follows the furnace temperature until the latter reaches 4000C. When the furnace temperature exceeds 400*C, still higher temperatures are measured in the powder which vary locally and can only be generated by spontaneous exotherraic reactions in the mass. Locally and for a short time, a temperature in the mass can exceed the furnace temperature by 1200C.

The Figures 2a, 2b, 3a and 3b show temperature profiles of pyrolyzed alkali battery powder with air supply and nitrogen supply at constant furnace temperatures of 600"C and 5000C respectively. The following can be seen from the figures: if air is blown through powdar treated at 600 0

C,

temperatures are measured which can rise in the center of the sample up to 8300C. In contrast, the supply of nitrogen reduces the occurrence of overtemperatures. The temperature differences (overtemperatures with respect to thG furnace temperature) are smaller than without gas supply.

At a furnace temperature of 500 0 C, a complex temperature profile is obtained with air supply and a temperatureregulating effect is obtained with nitrogen supply. In this last case, the temperature doer not exceed 550C.

The mercury residues in the powders treated under gas supply were measured at at least two positions (PI and P2), Table 2 displays the measurement results. From this it is seen that at 600 0 C furnace temperature, the removal of mercury under gas supply can be satisfactorily carried out both with air and with nitrogen, that in contrast at a furnace temperature of 500 0 C less reproducible and unsatisfactory results are achieved, both under nitrogen as under oxygen supply, for a treatment duration of 3 hours.

Example 3 2 kg of pyrolyzed unwashed battery powder are placed into a quartz vessel, which is put into a laboratory furnace (Naber type). The second thermal treatment is carried out at 600 0 C under nitrogen or air through-flow of one cubic meter per hour for various treatment times. The results are reproduced in Table 3.

At The Fo 1'n 10 prfie ofprlzdakl atrypwe iharsp Example 4 Results in the pilot furnace containing a stirrer ecrew 100 kg of pyrolyzed battery powder are placed into a pilot furnace having an internal stirrer screw.

The powder is stirred by the rotation to and fro of the screw (speed of rotation 5 to 7 revolutions per minute).

After each hour a sample is removed and analyzed. The entire treatment is carried out under a gas through-flow I of 2 cubic meters per hour of nitrogen. Table 4 shows the measurement results which were obtained with five different lots of pyrolyzed powder from the production.

Example Results in the continuously fed pilot furnace containing a stirrer screw 100 kg of pyrolyzed battery powder are placed into a pilot furnace having an internal screw. The furnace is replenished during the thermal treatment, while the powder is conveyed by the screw. The results are reproduced in Table 5 (in the two last samples the screw was rotated very slowly.

Example 6 Results in the industrial plant.

The pyrolysis furnace of the industrial plant was i used. Screened powder from the first pyrolysis was used from stocks of mixed batteries and from alkali batteries.

The mercury residues in these powders were 500 or 1000 ppm mercury. The charges were between 700 and 1300 kg. The batches were processed under a through-flow of 1 cubic meter per hour of nitrogen for 30 hours. Table 6 shows that at furnace temperatures of 700C, the ,A mercury residue of all batches could be satisfactorily reduced to a few ppm.

Example 7 1 kg of shredded pyrolyzed thermometers was placed into the laboratory pyrolysis furnace. The mixture actually composed of glass splinters, carbon, metal components and mercury contained a contamination of eapproximately 500 ppm mercury. The slag was kept for 3 hours at approximately 500°C and 1 m 3 /h of air was 1 r- L 8 Al J S12 passed through. The final weight of the slag was 940 g and had a mercury concentration of 9 ppm.

Example 8 1 kg of amalgam-containing, already-pyrolyzed sludges having an Hg content of 8000 ppm from dental practices was placed into the laboratory pyrolysis furnace and kept for 3 hours at a temperature of 850 0

C.

During this time, in total 5 m 3 of air were blown through the furnace. The final weight of the material removed was 970 g. A mercury concentration therein of 8 ppm was determined.

The flow diagram shown in process diagram 1 can obviously be advantageously changed in the context of the present invention. For example, the pyrolyzed and shredded material is screened and both the fine components and the coarse components are subjected to the second thermal treatment, without previously being washed: as a result, the energy for water evaporation of the washed and moist material is saved. The second pyrolysis of the coarse components (essentially Cu, Ni, Zn, Fr pieces) frees these, before the further treatment, from toxic Hg residues, so that this further treatment is facilitated.

The second thermal treatment of the coarse components is carried out essentially more rapidly and more easily than that of the powder.

Hitherto, the elatively high mercury portion in the powder had been considered to be unavoidable. The mercury contamination could not be reduced to the desired low contamination below 10 ppm even with formation of vacuum in the furnace or with nitrogen flushings. Only the apparently senseless repeated thermal treatment (whether in the form of a second pyrolysis or a calcination) of the already for the first time pyrolyzed material leads to the desired result.

13 TABLE 1 MATERIAL, TEMPERATURE NW NW W W Hg after TIME NM M NM M first pyrolys Mixed ,7000C 1.4 ppm 1.4 1.5 1.6 batteries 1.5 hours____ 150 ppm 7000C 1.4 1.5 1.8 1.7 4 hours____ 600 0 C 2.3 2 1.9 2.4 hours Alcali 7000C 218 88 457 354 batteries 1.5 hours 1500 ppm 7000C 103 67 394 203 4 700 0 C 5 13 150 139 8 hours 6000C 122 110 532 297 4 hours Hg-Zn! 7000C 11.8 13.4 /starch gel 1.5 hours 14,000 ppm 7000CI 9.4 11.1 hours f 1 14 TABLE 2 TEMPERATURE GAS P1 P2 SUPPLY (ppm Hg) (ppm H-g)- 600 0 C Air 4A8 3.4 600 0 C N 2 5.2 4.6 5000C Air 294 161 500 0 C N 2 141 12.5 TABLE 3 Hg TEMPERATURE TREATMENT TRANSPORT Hg INITIAL VALUE DURATION GAS FINAL VALUE (ppm) (HOURS) (ppm) 1500 600 0 C 8 N 2 3 1500 600 0 C 4 N 2 200 600 0 C 3.5 N 2 1000 6000W 3 AIR 4 1500 6000W 3 N 2 TABLE 6 Hg BATCH Hg INITIAL VALUE kg FINAL VALUE (ppm) __(ppm) 500 700 500 955 3 1000 1185 6 1000 1300 p-

I

15 TABLE 4 Hg FURNACE TREATMENT Hg INITIAL VALUE TEMPERATURE DURATION FINAL VALUE (ppm) (HOURS) (ppm) 770 700 0 C 1 2 21 3 6.6 _4 3 22 7000C 1 4.3 2 2.9 2.9 770 600 0 C 1 2 4.3 3.7 900 600 0 C 1 21 2 3.4 900 500 0 C 1 31 2 3 _4 5.4 I III TABLE Hg TEMPERATURE RESIDENCE TIME FURANCE TRANSPORT GAS Hg INITIAL VALUE IN THE FURNACE FEED FINAL VALUE (ppm) (minutes) kg/hour (ppm) 900 600 0 C 140 40 2m 3 /hour 11 2 1300 600 0 C 180 33 2m 3 /hour 4.7 2 1130 5500W 240 25 2m 3 /hour 4.2 2 1130 500 0 C 240 25 2m/hour 7.8 2 1200 700 0 C 480 12 6m 3 /hour 8.4 1200 7000C 480 12 6M 3 /hour 8.4

N

2 I

Claims

2. A process according to claim 1, wherein the second thermal treatment is io carried out under through-flow of oxygen-containing gas through the furnace.
3. A process according to claim 2, wherein the second thermal treatment is carried out under through-flow of oxygen-containing gas through the treated material.
4. A process according to claim 2 or 3, wherein the oxygen-containing gas is air. A process according to claim 1, wherein the second thermal treatment is carried out under through-flow of reducing gas through the furnace.
6. A process according to claim 5, wherein the second thermal treatment is carried out under through-flow of reducing gas through the treated material.
7. A process according to claim 5 or 6, wherein the reducing gas is nitrogen.
8. A process according to any one of claims 1 to 7, wherein the pyrolysis slag is 20 cooled and comminuted between the first pyrolysis and the second thermal treatment.
9. A process according to any one of claims 1 to 7, wherein carbon is added to the material to be treated.
10. A process according to claim 9, wherein the carbon is in graphite form.
11. A process according to claim 9 or 10, wherein the carbon is added to the 25 material prior to the first pyrolysis.
12. A process according to claim 9 or 10, wherein the carbon is added to the material prior to the second thermal treatment,
13. A process according to any one of claims 1 to 7, wherein the first pyrolysis is carried out between 450'C and 700C and the second thermal treatment is carried out between 500C and 700 0 C.
14. A process according to any one of claims 1 to 7, wherein the second thermal treatment is carried out in a continuous furnace to which the material to be treated is fed continuously and which mixes the said material during the treatment. A process according to any one of claims 1 to 7, wherein the material to be treated is composed of used equipment batteries.
16. A process according to claim 15, wherein the pyrolysis slag is shredded in the first step, after which the shredded pyrolysis slag is subjected to the second thermal treatment.
17. A process according to claim 15, wherein the unsorted batteries are nyrolyzed in a first step and then the pyrolysis slag is shredded, the coarse components are _f~Wro\WPT T.Q ur~~wT ,3 ;rt: 18 mechanically separated off from the fine components, after which the fine components are subjected to the second thermal treatment.
18. A process according to claim 15, wherein the unsorted batteries are pyrolyzed in a first process step and then the pyrolysis slag is shredded, washed and screened, whereupon the coarse components are separated off and subjected to an electrolysis and the screened out and washed fine material is subjected to the second thermal treatment.
19. A process substantially as hereinbefore described with reference to the accompanying figures. A process substantially as hereinbefore described with reference to any one of the Examples. Dated 10 May, 1995 Recytec S.A. Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON 'r r Cr C CC S C [G:\WPUSER\LIB1100546:TCW Ci