CA2054122C - Decontamination of soil containing chlorinated aromatics - Google Patents

Abstract

Moist soil contaminated with chlorinated aromatics is treated to dechlorinate the contaminants, using a known rotating kiln-type processor. A declorinating reagent, formed by contacting sodium hydroxide with polyethylene glycol, is mixed with oil and sprayed on the soil. In the kiln, the contaminants and reagent are gradually mixed and heated to about 315°C to effect substantial dechlorination. The product is then further heated to about 620°C to vaporize residual contaminants, oil and excess reagent. The vapours are collected, condensed and recycled to the mixing step.

Description

2 This invention relates to a process for dechlorinating

3 chlorinated aromatics such as polychlorinated biphenyls ("PCB's")

4 entrained in soil. The process involves use of a particular rotary kiln processor and a dechlorinating reagent derived from 6 the reaction of alkali metal hydroxide and a glycolate, 7 preferably polyethylene glycol.

BACKGROUND OF THE INVENTION
11 The present invention utilizes a known rotary kiln 12 processor which was originally developed to process oil sand.
13 The processor is known as the "ATP Processor". It is described 14 in Canadian Patent No. 1,121,749.
The invention further utilizes a modified version of 16 a known process for chemically dechlorinating chlorinated 17 aromatics using a reagent derived from the reaction of an 18 alkaline metal hydroxide and a glycolate. Such a process is 19 disclosed in United States patent No. 4460797, issued to Pytlewski et al. Similar processes have been disclosed in other 21 patents utilizing alkaline metal hydroxides in combination with 22 ethylene glycol, polyglycol, polyglycol monoalklyl ethers, and 23 dimethyl sulfoxide (DMSO).
24 Returning to the ATP Processor, it comprises inner and outer, generally tubular members herein referred to as tubes.
26 The tubes are generally coextensive, concentric, spaced apart and 27 horizontal. They are interconnected so as to form a unitary 28 rotatable tube assembly. Stationary end frames seal the first 29 and second ends of the outer tube. Drive means are provided for 20~122 1 rotating the outer tube, and thus the entire tube assembly, about 2 its longitudinal axis. A passageway extends longitudinally 3 through the inner tube and an annular passage is formed between 4 the tubes. The inner tube passageway is closed at its first end by a stationary end frame and at the second end by a vertical 6 closure plate. It is divided along its length by an upright 7 baffle, thereby creating two segregated sequential chambers or 8 ~zones" which combine to extend between the first and second ends 9 of the inner tube. The zone at the first end is referred to as the "preheat zone" and that at the second end as the 11 "vaporization zone". A feed stream comprising particulate solids 12 may be fed into the first end of the preheat zone by means of a 13 conveyor extending through the first end stationary end frame.
14 As the tube assembly is rotated, this feed is advanced longitudinally through the inner tube passageway. As it is 16 advanced, the feed is simultaneously cascaded. In addition, as 17 it moves through the preheat zone the feed is heated by heat 18 exchange with the wall of the inner tube. The inner tube is 19 heated by hot solids and flue gases moving countercurrently through the annular space. (The manner in which the hot solids 21 and flue gases are provided is described below). As a result of 22 progressive heating of the feed during its advance through the 23 preheat zone, contained water is vaporized. The produced steam 24 is suctioned from the preheat zone by a gas compressor and conduit assembly communicating with the zone at its first end.
26 Thus, in the preheat zone the solids are mixed as they cascade, 27 the feed is progressively heated and water is vaporized, and the 28 atmosphere in the vicinity of the baffle is caused to be 29 substantially oxygen-free, due to the back flow of steam. The 20~4122 .
1 preheated feed is discharged from the preheat zone through 2 helical chutes extending through the baffle. The chutes lead 3 into the vaporization zone. On entering the vaporization zone, 4 the preheated feed is mixed with hot solids recycled from the annular space. As a result, the feed is now heated to a 6 relatively high temperature. The hydrocarbon associated with the 7 solids is therefore vaporized and thermally cracked and some coke 8 is formed on the solid particles. A second gas compressor and 9 conduit assembly, communicating with the second end of the vaporization zone, suctions the hot gases from the zone and draws 11 them through a condenser. The coked solids are discharged from 12 the second end of the vaporization zone by means of a helical 13 chute extending through the closure plate at the second end of 14 the inner tube. The coked solids are discharged into the second end of the annular space. The annular space provides combustion 16 and cooling zones extending sequentially from the second end to 17 the first end thereof. Air is injected through the second 18 stationary end frame into the combustion zone. In addition, a 19 gas burner also extends through the second end frame and supplies supplemental heat to the combustion zone. Lifters extend 21 inwardly from the inner surface of the outer tube along its 22 length. In the combustion zone, these lifters lift and drop the 23 coked solids through the injected air stream. In the course of 24 this, the coke combusts and the solids are further heated. The resulting hot solids are advanced longitudinally through the 26 annular space from its second end toward its first end. A
27 portion of these hot solids are recycled, by means of a chute, 28 from the first end of the combustion zone into the first end of 29 the vaporization zone, as was previously described. The balance 20~4122 1 of the hot solids advance into the annular cooling zone, which 2 is coextensive with the preheat zone of the inner tube. Here the 3 hot solids are repeatedly lifted and dropped onto the outer 4 surface of the preheat section of the inner tube. Thus the preheat section is heated by contact with the shower of hot 6 solids and the flow of hot flue gases moving through the cooling 7 zone. At the same time the hot solids and gases are 8 correspondingly cooled, thus recovering useful heat from them.
9 The gases produced in the annular space are removed by a fan and conduit assembly communicating with the first end of the annulus.
11 The cooled solids are discharged from the cooling zone through 12 the first end frame by means of a chute.
13 In summary then, the operation of the ATP Processor 14 accomplishes the following when fed oil sand:
- progressively preheating the feed by heat exchange 16 through the tube wall with countercurrently moving 17 hot solids and gases, to vaporize the water 18 contained in the feed and back flow the produced 19 steam to yield an oxygen-depleted atmosphere at the hottest end of the preheat zone;
21 - pyrolysing the preheated feed in the vaporization 22 zone by mixing it with recycled hot combusted 23 solids in an oxygen-depleted atmosphere, thereby 24 vaporizing and thermally cracking hydrocarbons entrained in the feed, to produce coked solids 26 and oil vapours;
27 - transporting hot solids into and out of the 28 vaporization zone by means of chutes, essentially 1 preventing the movement of vapours from and into 2 the zone;
3 - heating and burning the coked solids in the 4 combustion zone, to provide a portion of the process heat;
6 - separately collecting the steam and hydrocarbon 7 vapours from the preheat and vaporization zones 8 and separately condensing them to yield in the 9 second case an oil fraction in liquid form;
- discharging oil-free solids as a tailings stream;
11 and 12 - discharging flue gases as a waste stream.
13 Turning now to the prior art Pytlewski et al process, 14 it involves:
- reacting alkaline metal hydroxide and a glycolate, 16 in the presence of oxygen, to produce a 17 dechlorinating reagent; and 18 - contacting chlorinated aromatics with the reagent, 19 again in the presence of oxygen, and optionally at elevated temperature in the order of 40 -21 180C, whereby the aromatics are dechlorinated.

24 The present invention involves a novel, continuous dechlorination process practised in the described ATP Processor.
26 The process comprises:
27 - mixing oil, alkali metal hydroxide, polyethylene 28 glycol and recycled liquid condensate containing 29 residual chlorinated aromatics;

20~122 1 - adding the resulting mixture to soil contaminated 2 with chlorinated aromatics and possibly containing 3 water, to provide a continuous processor feed 4 stream;
- advancing the processor feed stream through the 6 preheat zone of the ATP Processor, thereby 7 dispersing the added mixture in the soil, 8 progressively heating the feed from ambient 9 temperature to about 100 - 315C, and vaporizing any water in the feed;
11 - suctioning the gases produced in the preheat zone 12 using compressor and conduit means communicating 13 with the first end of the said zone, whereby there 14 is a back flow or countercurrent movement of the produced gases, relative to the direction of 16 advance of the feed;
17 - whereby the dechlorination reaction may proceed 18 rapidly at elevated temperature in the range of 19 about 100 - 315C in the substantial absence of oxygen and water;
21 - advancing the preheated feed stream into the 22 vaporization zone and mixing it therein with 23 recycled hot solids to raise the temperature of 24 the feed above about 480C, preferably to about 590C, thereby vaporizing and decomposing residual 26 chlorinated aromatics, vaporizing and cracking 27 contained oil and forming coked solids, and 28 removing the products of dechlorination from the 29 solids;

- 205~122 - suctioning produced gases from the second end of 2 the vaporization zone and condensing them to yield 3 liquid condensate containing residual chlorinated 4 aromatics and excess reagent, which condensate is recycled to the mixing step;
6 - advancing the coked solids into the combustion 7 zone, injecting air and adding heat to said zone 8 to burn coke and yield hot solids having a 9 temperature of at least 650C and preferably about 730C;
11 - recycling a sufficient portion of the hot solids 12 from the first end of the combustion zone, into 13 the first end of the vaporization zone, to heat 14 the feed stream as previously stated;
- using chutes at the first and second ends of the 16 vaporization and combustion zones to enable 17 movement of solids from zone to zone while 18 essentially preventing the movement of vapours 19 containing residual chlorinated aromatics from leaving the vaporization zone or oxygen-containing 21 gases from entering the vaporization zone, thereby 22 minimizing potential formation of oxygenated 23 chlorinated aromatics;
24 - advancing the balance of the hot solids and flue gases through the cooling zone and lifting and 26 dropping the hot solids onto the preheat tube to 27 heat the feed stream passing therethrough and to 28 cool the solids passing through the cooling zone;

20~4122 1 - discharging the solids reaching the first end of 2 the cooling zone, said solids being substantially 3 free of chlorinated aromatics; and 4 - suctioning gases from the first end of the cooling zone, removing entrained solids, and condensing 6 waters of combustion to yield solids, liquid 7 condensate and waste gases substantially free of 8 chlorinated aromatics.
9 In accordance with the invention, the dechlorinating reagent is applied to chlorinated aromatic-contaminated soil 11 under novel conditions and procedures, to thereby achieve a 12 viable extent of dechlorination. More particularly:
13 - continuous cascading or mixing of the fresh soil 14 and additives in the preheat zone is conducted to achieve a desirable extent of dispersal of the 16 additives, allowing the use of low amounts of 17 reagent;
18 - in conjunction with the mixing, the soil and 19 additives are indirectly heated by progressive heat transfer through the tube wall and raised in 21 temperature through a range of about 100 - 315C, 22 in the course of which the dechlorination reaction 23 proceeds rapidly;
24 - the dechlorination reaction is conducted in the absence of liquid water;
26 - the dechlorination reaction in the preheat zone 27 is followed by pyrolization in the vaporization 28 zone, to raise the temperature of the feed stream 29 sufficiently whereby residual contaminant and 1 excess reagent are volatilized together with 2 hydrocarbons and the product is suctioned from 3 the zone as a gas, thereby separating the 4 contaminant and unreacted reagents from the soil.
The gases are then condensed to form a liquid 6 which is recycled to re-process residual 7 contaminant.
8 The process has been found capable of safely and 9 continuously processing and dechlorinating polychlorinated biphenyls (PCB's) very quickly (typically about 15 minutes 11 residence time in the preheat zone within the ATP Processor) and 12 lowers PCB content in the tailings effluent to non-detectable 13 levels.

DESCRIPTION OF THE DRAWING
16 Figure 1 is a schematic drawing showing the ATP
17 Processor, condenser and mixer in side elevation.

The invention has been demonstrated in a pilot run 21 using an ATP Processor 1, condenser 2 and mixer 3, shown in 22 Figure 1.
23 The processor 1 comprised inner and outer tubular 24 members 4 and 5. The first end of the inner tubular member 4 was sealed by a first stationary end frame 6. The second end of 26 the inner tubular member 4 was sealed by closure plate 7. The 27 first and second ends of the outer tubular member 5 were sealed 28 by second and third stationary end frames, 8 and 9 respectively.

205~122 -1 The inner tubular member 4 formed an internal 2 passageway 10 which consisted of sequential preheat and 3 vaporization zones A and B extending between said member's first 4 and second ends.
The outer tubular member 5 was generally coextensive, 6 concentric and radially outwardly spaced from the inner tubular 7 member 4. An annular space 11 was thus formed between the 8 tubular members 4 and 5. This space 11 comprised combustion and 9 cooling zones C and D extending sequentially between the second and first ends of the outer tubular member 5.
11 The tubular members 4 and 5 were structurally 12 interconnected so that they would rotate together. A drive 13 system 12 was provided for rotating the outer tubular member 5 14 about its longitudinal axis.
Inwardly protruding, angled plates 13 were optionally 16 affixed to the inside surfaces of the inner and outer tubular 17 members 4 and 5 for assisting in advancing or retarding 18 particulate solids flow through the passageway 10 and annular 19 space 11.
A vertical baffle 14 separated and isolated the preheat 21 zone A from the vaporization zone B. An open-ended chute 15 22 extended through the baffle 14 at its periphery, for enabling 23 particulate solids to move from the preheat zone A into the 24 vaporization zone B. The flow of gases through the chute 15 was essentially prevented by the charge of solids present in the 26 chute passage 16 at any given moment.
27 An open-ended chute 18 extended through the second 28 closure plate 7 at its periphery, for moving coked solids from 29 the vaporization zone B in to the combustion zone C. Again, the 1 movement of gases between the vaporization zone B and the 2 combustion zone C was precluded by the second end closure plate 3 7 and the solids charge in the chute 18.
4 A conveyor 19 extended through the first end frame 6, for delivering feed to the passageway 10. Thus feed could be 6 introduced into the first end of the preheat zone A.
7 A burner 21 extended through the third end frame 9, for 8 supplying supplemental heat to the combustion zone C. In 9 addition, an air pipe and air fan assembly 22 extended through the third end frame 9, for supplying a flow of pressurized air 11 to the combustion zone C. Non-condensible gases 24 from the 12 condensor 2 could be optionally burned as a supplemental fuel or 13 were burned in a flare stack 39.
14 Insulating refractory 45 was present, installed on the inside wall 24 of the outer tubular member 5, reducing the loss 16 of heat from the annulus 11.
17 Lifters 23 were provided, attached to the wall 24 of 18 the outer tubular member 5 along its inside surface through the 19 length of the combustion zone C. The lifters 23 were adapted to lift coked solids and drop them through the air stream being 21 injected into the combustion zone by the air pipes 22.
22 Thus, in the combustion zone C, the coked solids were 23 lifted and dropped in the injected air and heated, thereby 24 initiating combustion of the coke to raise the temperature of the solids particles.
26 Some of the hot solids issuing from the combustion zone 27 C were recycled into the first end of the vaporization zone B by 28 the open-ended chutes 25 installed on the periphery of the inner 29 tubular member 4. Advancing solids within the chute passage 37 1 essentially blocked the free transference of vapours from the 2 combustion zone C to the vaporization zone B. The balance of the 3 hot solids were advanced into the cooling zone D.
4 Lifters 26 were also provided in the cooling zone D, attached to the wall 24 of the outer tubular member 5 at its 6 inside surface. The lifters 26 were adapted to lift the hot 7 solids moving through the zone and drop them on the preheat wall 8 portion 27 of the inner tubular member 4.
9 Thus heat was transferred to the bed 28 of feed advancing through the preheat zone A. The heat was absorbed by 11 the preheat portion wall 27 of the inner tubular member 4, from 12 the hot flue gases moving through the cooling zone D and by 13 contact with the hot solids 29 contacting the wall 27. The 14 absorbed heat moved through the wall 27 and was transferred to the particles of the bed 28, thereby progressively heating the 16 bed in the course of its passage through the preheat zone A.
17 Simultaneously, of course, the solids and gases in the cooling 18 zone D were progressively cooled as they moved between its second 19 and first ends.
Two gas compressor and conduit assemblies 30, 31 were 21 provided to suction gases from the first end of the preheat zone 22 A and the second end of the vaporization zone B, respectively.
23 A fan and conduit assembly 32, was provided to suction gases from 24 the first end of the cooling zone D.
The gases removed from the preheat zone A through 26 assembly 30 were condensed in a first condenser 33. The non-27 condensed gases 40, consisting mostly of air, were routed to the 28 combustion zone C for combustion. The gases removed from the 29 vaporization zone B through assembly 31 were condensed in a 20S~122 1 second condenser 2. The non-condensed gases 34, were 2 preferentially burned as fuel, excess gases being burned in a 3 flare stack 39. The flue gases were removed by the assembly 32 4 from the first end of the cooling zone D, were cleaned in solids removal equipment 41 (not discretely detailed), and were vented 6 from a stack 42.
7 The cooled solids issuing from the first end of the 8 cooling zone D passed through an outlet 35 in the second end 9 frame 8 and were discharged by conveyor assemblies 36 as tailings.
11 The condensate and make-up oils from the second 12 condenser 2 were recycled to the mixer 3 where they were blended 13 with some reagent from the batch mixer 45. The batch mixer 45 14 was a staging area where reagent was prepared by mixing solid sodium hydroxide pellets and liquid polyethylene glycol having 16 a molecular weight of about 400 (PEG 400). The product mixture 17 from mixer 3 was then sprayed onto the feed entering the preheat 18 zone A by sprayer 38.

EXAMPLE
21 The invention is now exemplified by describing a pilot 22 run conducted on soil contaminated with PCB~s using the ATP
23 Processor just described.
24 Contaminated road surface soils containing PCB's were treated at a continuous feed rate of 7.3 tonnes per hour. The 26 ATP Processor treated 960 tonnes of soils, operating 24 hours per 27 day, for 5 days. The average in situ contamination level was 27 28 ppm with a range of 9 through 172 ppm recorded for the test 29 period. The test objective for the treated solids PCB limit was 205~122 1 2 ppm. The treated solids were sampled every 12 hours, and 2 analyzed for PCB's. The PCB results were non-detectable at 0.5 3 ppm, using EPA Method 8080. The mineral fraction of the soils 4 comprised 54 % sand and gravel, 16 % clays, and 30 % silts with a soils moisture content of 15 % moisture. At 7.3 tonnes/hour 6 and 27 ppm PCB's, this represented 0.2 kgs/hr of fresh PCB feed 7 to the ATP Processor.
8 The reagent and recycle oil stream was sprayed into the 9 preheat zone at an average rate of 167 kgs per hour. This oil stream was composed of 6.8 kgs/hr of sodium hydroxide and 11 polyethylene glycol reagent (about 0.9 kgs/tonne of feed soil) 12 and 0.06 kgs/hr of a steady state concentration of residual PCB's 13 in 160 kgs/hr of an oil stream.
14 The oil stream was a mixture of 0.93 specific gravity make-up oil and excess reagent condensed from the vaporization 16 zone. The 0.93 SG oil was introduced as a carrier oil to 17 provide enough liquid for dilution of dusts contained in the 18 hydrocarbon vapour condensing system and as a mechanism for good 19 dispersal of the small reagent mass into the incoming soil feed.
The test average make-up oil amount was about 50 kg/hour.
21 The reagent mixture was prepared by mixing 1 part 22 sodium hydroxide pellets into 10 parts preheated polyethylene 23 glycol. The mixture ratio was performed on a mass basis. The 24 mixture was prepared in batches of about one week's operation.
The mixing was performed with a 15 rpm mixer within a heated 26 vessel at about 80C.
27 The above ope~ation was accomplished in a transportable 28 processing plant implementation of the ATP Processor system. The 29 dechlorination or preheat zone was housed within a processor of 20~4122 1 an overall length of about 15.25 meters and an outer diameter of 2 3.7 meters. The transportable ATP Processor was characterized 3 by the following operating parameters:
4 - preheat zone defined by about 4.3 meters in length and 2.1 meters in diameter;
6 - vaporization zone defined by about 3.4 meters in 7 length and 1.8 meters in diameter;
8 - an annular space defined by the outside diameters 9 of the preheat and vaporizations zones and the inner diameter of the refractory lined outer 11 tubular member;
12 - a combustion zone defined by an inner diameter of 13 1.8 meters, an outer diameter of 3.4 meters and 14 an overall length of 5.0 meters;
- a cooling zone defined by an inner diameter of 2.1 16 meters, an outer diameter of 3.5 meters and an 17 overall length of 4.3 meters;
18 - preheat zone wall thickness being 10 millimeters;
19 - an overall solids retention time in the preheat zone being 45 minutes;
21 - the preheat zone temperature profile was observed 22 as 21C at the first end, characteristically 23 rising swiftly to 100C as the water boiled off, 24 remaining at such temperature until such time as all the water was evaporated at about the 2/3 26 length point (for this particular test), after 27 which the temperature again climbed to about 28 315C;

20~122 1 - the cooling zone profile being roughly linear from 2 730C at the second end to 290C at the first end 3 or tailings discharge point;
4 - the suction pressure on the preheat zone being slightly sub-atmospheric at - 0.09 mmHG;
6 - the suction pressure on the vaporization zone 7 being - 0.24 mmHG;
8 - the suction pressure on the annular space being -g 0.19 mmHG;
- the recycle solids flow being 2 times the preheat 11 exit solids flow for a rate of 12250 kgs/hour;
12 - the recycle solids temperature being 730C;13 - the resultant vaporization zone temperature being 14 620C;
- the residual PCB and carrier oils being vaporized 16 and pyrolysed to yield ~pproximately 20 % coke, 17 15 % gas, and 65 % liquid condensate;
18 - the coked vaporization zone solids providing about 19 176 kilojoules/sec of heat to the combustion zone;
- the non-condensed off gases from the hydrocarbon 21 condensor providing an additional heat of about 22 528 kilojoules/sec;
23 - the natural gas burners providing supplemental 24 heat of about 1055 kilojoules/sec;
- 4000 cubic meters/hour of air was added to the 26 combustion zone to provide oxygen for the 27 combustion of the coke, off gases, and natural 28 gas fuels;

1 - preheat condensate oils were combined with the 2 condensed oils from the hydrocarbon condensor;
3 - preheat condensate water was combined with the 4 hydrocarbon condensor water stream;
- the hydrocarbon condensor condensed oils were 100%
6 recycled to the preheat zone with no system 7 accumulation; and 8 - the hydrocarbon system combined condensed waters 9 being treated, the filtrate and carbon bed absorbing mediums being reprocessed by the ATP
11 processor when dirty, resulting in no off-site 12 disposal of treatment consumables.
13 The effluents from the ATP plant were treated water, 14 solids as tailings, and flue gas stack gas. The treated water had discharge quality of about 36 ppb or 0.0002 mass fraction of 16 the 0.2 kg/hour of PCB's fed to the ATP Processor. The stack gas 17 contained an average of 1.8xlO~5kg/hr PCB's or 0.00009 mass 18 fraction of the feed PCB's. The treated soils or tailings 19 contained less than 64 ppb or less than .002 mass fraction of the feed PCB's. Overall, less than .00229 mass fraction or 1 % of 21 the original PCB was released.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A continuous process for dechlorinating chlorinated aromatics present as contaminants in soil, using an ATP Processor comprising an inner tubular member, forming an internal passageway comprising sequential preheat and vaporization zones extending between said member's first and second ends, and an outer tubular member having first and second ends corresponding with those of the inner tubular member, said outer tubular member being generally coextensive, concentric and radially spaced outwardly from the inner tubular member to form an annular passage between them which provides sequential combustion and cooling zones extending between the outer tubular member's second and first ends, said tubular members being rotatable together whereby the particulate solids of the soil may be cascaded and advanced through the preheat and vaporization zones and back through the combustion and cooling zones, said processor having a baffle separating the preheat and vaporization zones, chute means for enabling the particulate solids to move through the baffle from the preheat zone to the vaporization zone, first means for suctioning gases from the first end of the preheat zone, second means for suctioning gases from the vaporization zone, chute means for recycling hot particulate solids from the first end of the combustion zone to the first end of the vaporization zone, closure plate for closing the second end of the inner tubular member, stationary end frame means for closing the first end of the inner tubular member, stationary end frame means for closing the first and second ends of the outer tubular member, means for injecting air into the combustion zone, burner means for supplying supplemental heat to the combustion zone, means for lifting and dropping particulate solids in the combustion zone, means for lifting and dropping the particulate solids in the cooling zone whereby they contact the preheat portion of the inner tubular member to heat its wall, means for supplying the contaminated soil into the preheat zone, means for removing cooled particulate solids from the first end of the cooling zone, and means for suctioning gases from the first end of the cooling zone, said processor being associated with condensing means adapted to receive and condense hot gases suctioned from the vaporization zone, and means for mixing reagents, said process comprising:

(a) mixing oil, alkali metal hydroxide, polyethylene glycol and recycled condensate containing chlorinated aromatics to produce an additive stream;
(b) adding the additive stream to the contaminated soil, containing chlorinated aromatics, to provide feed for the processor;
(c) advancing the feed through the preheat zone while simultaneously cascading it and progressively heating it by heat exchange with the wall of the inner tubular member to raise its temperature to within the range of 100 - 315°C, while simultaneously suctioning gases produced in the preheat zone from the first end of said zone, so that water contained in the feed is vaporized, backflowed through the zone and removed, to create an oxygen-depleted atmosphere at the second end of the zone;

(d) further advancing the preheated feed through the baffle and into the vaporization zone and mixing it therein with recycled hot solids to raise the temperature of the feed to a temperature sufficient to vaporize and pyrolyze contained oil, produce coked solids and vaporize residual chlorinated aromatics;
(e) suctioning produced gases from the vaporization zone and condensing them to yield liquid condensate containing some residual chlorinated aromatics;
(f) recycling the condensate from step (e) to the mixing step of step (a);
(g) discharging the coked solids from the vaporization zone into the combustion zone while simultaneously restricting movement of the chlorinated aromatic vapours with the coked solids being discharged;
(h) lifting and dropping the coked solids in the combustion zone and combusting and heating them by contacting them with injected air and added supplemental heat, to produce hot solids having a temperature of at least about 650°C and flue gases;
(i) advancing the hot solids through the combustion zone and recycling a sufficient portion of them into the first end of the vaporization zone to heat the feed as previously stated in accordance with step (d) while simultaneously restricting oxygen-containing flue gases from entering the vaporization zone;

(j) advancing the balance of the hot solids through the cooling zone and lifting and dropping them onto the preheat section of the inner tubular member, so that the wall of the preheat section of the inner tubular member is heated by contact with the hot solids and flue gas moving through the cooling zone;
(k) suctioning produced gases from the annular space;
and (l) discharging cooled solids from the first end of the cooling zone, said solids being substantially free of chlorinated aromatics.