WO1988010234A1 - Procede de traitement de l'amiante - Google Patents

Procede de traitement de l'amiante Download PDF

Info

Publication number
WO1988010234A1
WO1988010234A1 PCT/DK1988/000105 DK8800105W WO8810234A1 WO 1988010234 A1 WO1988010234 A1 WO 1988010234A1 DK 8800105 W DK8800105 W DK 8800105W WO 8810234 A1 WO8810234 A1 WO 8810234A1
Authority
WO
WIPO (PCT)
Prior art keywords
asbestos
fibres
reaction
process according
acid
Prior art date
Application number
PCT/DK1988/000105
Other languages
English (en)
Inventor
Belinda Bjerre
Emil SØRENSEN
Original Assignee
Forskningscenter Risø
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Forskningscenter Risø filed Critical Forskningscenter Risø
Publication of WO1988010234A1 publication Critical patent/WO1988010234A1/fr

Links

Classifications

    • A—HUMAN NECESSITIES
    • A62—LIFE-SAVING; FIRE-FIGHTING
    • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
    • A62D3/00—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances
    • A62D3/30—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances by reacting with chemical agents
    • A62D3/36—Detoxification by using acid or alkaline reagents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
    • B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
    • B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
    • B09B3/0066—Disposal of asbestos
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F5/00—Compounds of magnesium
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F5/00—Compounds of magnesium
    • C01F5/14—Magnesium hydroxide
    • C01F5/20—Magnesium hydroxide by precipitation from solutions of magnesium salts with ammonia
    • A—HUMAN NECESSITIES
    • A62—LIFE-SAVING; FIRE-FIGHTING
    • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
    • A62D2101/00—Harmful chemical substances made harmless, or less harmful, by effecting chemical change
    • A62D2101/40—Inorganic substances
    • A62D2101/41—Inorganic fibres, e.g. asbestos

Definitions

  • the present invention relates to a process for decomposing asbestos fibres.
  • Asbestos fibres have been a preferred constituent of a wide range of materials for many years owing to the excellent properties of the fibres regarding strength, flexibility, resistance towards chemicals and heat, etc.
  • the asbestos fibres have been used to reinforce building materials and rubber and plastic materials, and have been used as constituents in brake linings, electrical and heat insulation materials, and fireproof fabrics.
  • the present invention discloses a novel process for decomposing as ⁇ bestos fibres.
  • the process comprises reacting the asbestos fibres with an acid component so as to obtain as a reaction product which contains a reduced aiount of an asbestos fibrous structure, pre- ferably substantially no asbestos fibrous structure, and in any event an amount of asbestos fibres which constitutes less than 30% of the reaction product.
  • the amount of asbestos fibres present in a specific reaction product may be determined by different methods. The three most commonly used methods are 1) X-ray diffraction analysis of the reaction product, 2) visual inspection of the reaction product, preferably by use of a microscope, and 3) Mg-content determination of the solid part of the reaction product, e.g.
  • the Mg- content of the solid part of the reaction product will be a true measure of the amount of asbestos fibres present in the reaction product, as the magnesium constitutes a central and necessary element of the asbestos fibrous structure.
  • the third method is carried out on the solid part of the reaction product.
  • the solid part of the reaction product is defined as the residue resulting from filtering the reaction product in vacuo through a filter of the type Whatman®41 placed in a B ⁇ chner funnel and drying the filter cake in an oven at a temperature of about 105 ⁇ C until dryness of the product is achieved, e.g. for about 1 hr.
  • the conditions under which this third method are to be carried out are to be chosen so that no Mg-containing compounds beside the asbestos fibres are present in the solid part of the reaction product.
  • the term "asbestos" is a common designation for impure magnesium silicate minerals which occur in fibrous form.
  • the main classes of asbestos are serpentine asbestos and amphibole asbestos, and it is mainly the serpentine asbestos which may be decomposed by the process of the invention.
  • Serpentine asbestos or white asbestos is mainly composed of the mineral chrysotile, M 3Si2 ⁇ 5(OH , a magnesium silicate.
  • Chrysotile has the following chemical composition:
  • the variations in the above ranges are mostly due to impurities in the chrysotile.
  • the colour of the chrysotile may vary from white, grey or green to yellowish as reported by M.S. Badollet, "Asbestos a
  • the fibres are reported to be hollow cylindrical tubes having an outer diameter of 200-250 A and an inner diameter of 20-50 A, F.L. Pundsack, J. Phys. Chem 60, 361 (1956); 65, 30 (1961). Due to their hollow structure, the fibres may absorb colouring agents and the chrysotile fibres may be identified by staining with iodine in glycerine (1%), M. Morton, .G. Baker: H. Frank: Asbest, Becker und Haag Hamburg 1952.
  • Iodine in glycerine selectively confers a very dark brown colour to the chrysotile fibres, whereas other particles obtain a slightly yellow colour when treated with this colouring agent.
  • the density of the chrysotile is 2.4-2.6 g/cm , as reported by F.L. Pundsack, J. Phys. Chem 60, 361 (1956); 65, 30 (1961) .
  • the surface area is dependent on the degree of dispersion of the fibres and may vary from 4 to 50 m 2 /g, which is a higher value than is known from other textile fibres; F.L. Pundsack, J. Phys.
  • the diameter of the chrysotile fibres is about 0.02 ⁇ m.
  • the chrysotile fibres are strong and flexible and may be spun.
  • Amphibole asbestos is composed of various silicates of magnesium, iron, calcium and sodium.
  • the fibres belonging to this class differ from the serpentine asbestos fibres in being more hard and stiff as well as more brittle and more resistant to chemicals and to heat than the serpentine asbestos fibres.
  • the diameter of these fibres is about 0.1 ⁇ m.
  • the most common members of this class of asbestos are crocidolite (blue asbestos) and amosite, which is also termed cummingtonitgrunerite (brown asbestos) .
  • the asbestos fibres are conventionally obtained from asbestos-- containing rocks.
  • fibres as used herein is intended to define any fibrous structure of the asbestos material which may be observed.
  • the fibres may be raw fibres as well as fibres which have been subjected to any kind of treatment or modification, e.g. spinning or weaving.
  • the fibres are often connected to each other to form bundles or branched aggregates, and the fibrous structure is in itself of a very characteristic appearance.
  • the appearance of the fibres differs from the appearance of other types of fibres and the asbestos fibres may be easily recognized.
  • the presence of asbestos fibres is determined by either of the above mentioned methods or a combination of these. In Fig.
  • FIG. 2 shows the result of a microscopic examination of a bundle of chrysotile fibres which has been stained with 1% iodine in glycerine.
  • the fibres were examined at a magnification 100.
  • the fibrous structure of the asbestos fibres of Fig. 2 is evident.
  • Fig. 3 shows the structure of the product resulting from treatment of asbestos fibres with .ammonium sulfate at a temperature of 260°C such as is described, e.g. in Example 4.
  • the reaction product has been stained with crystal violet and has been examined under microscope at a magnification of 100. It is evident in Fig. 3 that the amount of asbestos fibrous structure has been reduced be the treatment.
  • Fig. 3 shows the structure of the product resulting from treatment of asbestos fibres with .ammonium sulfate at a temperature of 260°C such as is described, e.g. in Example 4.
  • the reaction product has been stained with crystal violet and has been examined under microscope at a
  • FIG. 3 is an illustrative example of a decomposed structure, especially in comparison to the asbestos fibrous structure of Fig. 2.
  • asbestos fibres are treated with an acid component under conditions which are sufficient to obtain a substantial decomposition of all of the asbestos fibres, preferably resulting in a non-fibrous, porous and normally particula- te material, the composition of which depends on the composition of the asbestos in question.
  • the reaction product which in the present context refers to the solid as well as liquid material which result from the reaction of the asbestos fibres and the acid component, is constituted by a solid part which mainly contains a non-fibrous material of silicic acid and a liquid part which mainly contains a solution of various salts of magnesium and silicic acid.
  • a more fibre-like solid material may result from the decomposition reaction.
  • such fibre-like structures are porous and do not possess any strength, i.e. are not of an asbestos fibrous structure. It is contemplated that these structures may be totally eliminated by being subjected to mechanical treatmen .
  • the term "decomposed” or any equivalent term as used herein generally should be understood to mean that substantially no fibrous structure as defined above may be observed in the material in question.
  • neither X-ray diffraction analysis nor microscopic examination should show any substantial fibrous structure and in any event an amount which does not exceed 30% of the reaction product.
  • the Mg-content of the treated material should be lower than 30% of the Mg-content of the initial asbestos fibres which have not been subjected to decomposition, provided that no Mg-precipitation has occured.
  • the process of the present invention will in most cases be adapted so as to result in a more efficient decomposition of the asbestos fibres.
  • X-ray diffraction analysis of the reaction product should show less than about 20% of an asbestos fibrous structure, e.g. less than about 10% of an asbestos fibrous structure.
  • the process of the invention is carried out so as to obtain a decomposition efficiency resulting in less than about 5% of an asbestos fibrous structure, more preferably less than about 2% of an asbestos fibrous structure, e.g. less than about 1% an asbestos fibrous structure or 0.5% an asbestos fibrous structure, and most preferably less than about 0.1% of an-asbestos fibrous structure in the reaction product as determined by X-ray diffraction analysis.
  • the process of the invention is carried out so as to result in a substantially total decomposition.
  • the asbestos fibre determination may under conditions where no Mg-precipitation occurs be combined or replaced with determination of the Mg-content of the solid part of the reaction product.
  • the conditions under which the decomposition is performed are not critical and may be established by combinations of different parametres.
  • the important and determinative reaction parametre is the time required to obtain the substantial decomposition of the fibrous structure of the asbestos material.
  • the reaction may be carried out under quite simple circumstances, i.e. there is generally not put any heavy demands on the equipment used and generally no particular precautions should be taken during the period of reaction with the exception of the required reaction time.
  • the time needed to effect the substantial total decomposition will depend on i.a. the acidity of the asbestos fibres to be decomposed, the acid component(s) employed, the reaction temperature and other reaction conditions. Typically, the reaction will last several days, weeks or even months.
  • the term "acid component” means any component or substance which is capable of confering the necessary acidity to the asbestos fibres so as to allow the decomposition reaction to proceed.
  • the acid component is in most cases an acid in its con ⁇ ventional meaning, e.g. an acid of the type mentioned below, but may also be any other substance which either inherently or when treated in a suitable manner provides the necessary acidity to the reaction mixture.
  • various acidic salts dissolved in a suitable liquid, such as water will be considered to be an acidic component.
  • the specific conditions under which the asbestos fibres and the acid component are reacted may vary considerably.
  • the temperature and pressure conditions as well as the mechanical and other treat ⁇ ments of the asbestos fibres and acid component(s) to be reacted may vary within wide limits and may be combined in a number of different ways.
  • the conditions under which a particular reaction is carried out may thus be chosen so as to comply with the available equipment and suitable reaction conditions for the treatment in question.
  • the reaction should be allowed to proceed for sufficient time to obtain the substantial decomposition of the asbestos fibres. Consequently, the reaction time will be the most significant parametre with which the extent of the reaction, and thus the degree of decomposition, is regulated.
  • reaction mixture means the combination of asbestos material and acid component(s) , which may be in the form of a homogenous or inhomogenous suspension of the asbestos fibre-containing material and the acid component(s) in a suitable suspension liquid such as water, a combination of asbestos- containing material and acid component(s) having a more dry appearan- ce, or another combination in which the decomposition reaction may be carried out.
  • the asbestos fibres may be decomposed when subjected to acidic conditions, whereas they remain intact under basic conditions.
  • the acidity of the reaction mixture is preferably kept at a pH of less than about 5, as higher pH-values have been found to be ineffective for the decomposition reaction.
  • the rate at which the desired degree of decomposition is obtained is influenced by the acidity of the suspension of asbestos fibres and acid component.
  • the substantial decomposition of the asbestos fibres is obtained with a shorter reaction time when the acidity is high, i.e. when the pH is low. Accordingly, in cases where a relatively fast decomposition of the asbestos fibres is advantageous, the reaction is preferably carried out at a high acidity, e.g.
  • the pH is kept below about 1, such as less than about 0.5, e.g. about or below 0.1 or even about or below 0.001.
  • the pH of the reaction mixture is preferably measured at regular or. irregular intervals, and additional acid is supplied so as to adjust the acidity of the reaction mixture to the desired pH in the desired period of time, e.g. throughout the main part of the reaction.
  • the measuring of the acidity and addition of acid component(s) may be performed automatically, e.g. by use of a pH-stat, or semi-auto ⁇ matically as well as manually.
  • a variety of acids may be employed to establish the above mentioned desirable acidities. Thus, strong acids as well as weaker acids may be employed. Sulphuric acid has been found to be particulary effective in decomposing the asbestos fibres, as illustrated in Examples 5 and 6. However, also hydrochloric acid, nitric acid and phosphoric acid are expected to be effective. The relatively weak oxalic acid has also been found to be capable of decomposing the asbestos fibres. Other relatively weak acids which are contemplated to be effective are formic acid, acetic acid, ascorbic acid and citric acid. Also, as described in detail in the following, an aqueous solution of ammonium sulfate is effective in decomposing asbestos fibres.
  • acids having a pK s of about 5 or lower will be useful for the present purpose.
  • combinations of the above mentioned acid components or other acid components which may prove to be effective may also be employed in the process according to this aspect of the invention.
  • treatment of the asbestos fibres at rather low acidities, i.e. at high pH-values leads to a slow decomposition of the fibrous structure which may turn out to be substantial when being performed for a sufficient period of time.
  • the fibrous structure of the asbestos material when exposed to acid rain may be affected or modified or even decomposed to a certain degree.
  • the term "acid rain” is in accordance with the conventional used definition defined as rain or other precipitation containing acidic components, e.g. sulphuric, nitric and hydrochloric acid, which mainly result from industrial combustion.
  • acidic components e.g. sulphuric, nitric and hydrochloric acid
  • the decomposition reaction may, however, be favoured when certain additives are present in the reaction mixture.
  • One kind of additive which may accomodate the decomposition reaction is a magnesium-binding agent such as a magnesium-complexing agent and/or a magnesium-precipitating agent.
  • the decomposition of chrysotile, which constitutes the main part of the asbestos fibres Is believed to be carried out in accordance with the following reaction scheme:
  • Mg-binding agent e.g. Mg-complexing agent and/or Mg-precipitating agent
  • Mg-complexing agent e.g. Mg-complexing agent and/or Mg-precipitating agent
  • EDTA ethylenediaminetetraacetlc acid
  • Mg-precipitating agent is oxalic acid, the use of which leads to the formation of magnesiumoxalate, and a combination of phosphoric acid and an ammonium ion containing compound, the use of which leads to the formation of magnesium ammonium phosphate.
  • oxalic acid the use of which leads to the formation of magnesiumoxalate
  • ammonium ion containing compound the use of which leads to the formation of magnesium ammonium phosphate.
  • phosphoric acid and ammonium sulfate or another ammonium-containing compound will be especially useful.
  • any partly decomposed asbestos fibrous structure may be divided or comminuted to a harmless structure or a structure which to a higher extent will be exposed to the action of the acid component(s) .
  • the physical treatment of the asbestos material may be performed in a wide range of different ways and may i.a. depend on the equipment in which the decomposition reaction is carried out as well as on the amount and nature of the asbestos material to be treated and the acid component(s) employed.
  • reaction When the reaction is carried out in batch, e.g. in a container or vessel such as a batch reactor, this may be by stirring or by another type of mixing such as shaking or stirring or mixing may be intermittent or continuous. If stirring or mixing is required during the reaction, it may thus be convenient to employ a reaction vessel which is equipped with a means of stirring.
  • a reaction vessel which is equipped with a means of stirring.
  • this may e.g. be performed in a reactor of the type described below for use in a particular aspect of the present invention, which will be explained in detail below.
  • a reactor of this type the turbulent flow of the suspension to be reacted will result in a sufficient physical treatment of the suspension.
  • the physical treatment may, of course, also be obtained in a combined batch and continuous process.
  • the temperature at which the decomposition of the asbestos material is carried out is not critical for the obtainment of a successive decomposition result.
  • the temperature may vary widely, e.g. in the range of 0-320°C. At temperatures which are lower than 0°C substantially no reaction is obtained, whereas temperatures higher than 320°C afford supercritical reaction conditions. In most cases it has been found that the decomposition of the asbestos fibres according to the invention is accelerated when heat is applied to the reaction mixture.
  • the use of temperatures which exceed the boiling temperature of the liquid, if present, requires that the reaction may be pressurized.
  • the temperature is preferably below 100 ⁇ C, e.g.
  • the temperature is preferably higher, e.g. above 200°C. This will be specified below.
  • the amount of asbestos fibre material to be treated and the amount of acid component(s) used may vary widely. In most cases, however, it is preferred that the asbestos fibres constitute about 1-10% of the reaction mixture as higher concentrations of asbestos fibres will make the contact between the acid component(s) and the asbestos fibres difficult.
  • the fibres to be treated are preferably shorter than 200 mm. The amount and size of asbestos fibre material to be treated is further specified below.
  • the asbestos fibres need not be isolated from materials in which the fibres are contained in admixture with other constituents before being subjected to the process of the invention.
  • the process of the invention may be carried out in two or more steps, the reaction conditions of each step being as de ined in the present specification and claims.
  • precondition the asbestos fibres prior to the real decomposition treatment, i.e. the reaction with the acid component(s) , by physical ⁇ ly treating the fibres, e.g. by comminution or by suspending the fibres in a suitable liquid which is passed through a flow reactor, optionally at an elevated temperature and/or pressure, so as to obtain a more fine and thus more reactive dispersion of the fibrous material.
  • the process of the invention may be carried out under conditions of recycling.
  • the process may be carried out under a wide variety of conditions.
  • no particular acid resistent material need to be employed for the equipment in which the reaction is carried out, as long as rather moderate acidities of the reaction mixture is used.
  • the reaction according to the process of the invention is allowed to proceed in a simple container or vessel, wherein the asbestos fibres are introduced together with an aqueous solution of the acid component(s) , e.g. IN sulphuric acid.
  • the amount of asbestos fibres are preferably in the range of 1-5% and it is preferred that the asbestos fibres are of a length as defined below, e.g. shorter than 200 mm.
  • the acid component(s) in solution is supplied in an amount which ensures a pH of about 1.
  • the asbestos fibres and the acid component(s) are then allowed to react at ambient temperature and pressure, e.g.
  • the acidity of the content of the container is adjusted to pH 1, preferably by use of a pH-stat.
  • the reaction is allowed to proceed for sufficient time to obtain a substantial decomposition of the asbestos fibrous structure, the sufficient time typically being 50-60 days or longer, depending on the amount and nature of the asbestos fibres to be decomposed.
  • the solid part of the reaction product may be discarded together with the liquid part from which the Mg content optionally have been recovered.
  • the above explained system for carrying out the process of the invention may of course be adapted so as to optimize the decomposi ⁇ tion reaction.
  • the preconditioning may comprise exposure to a weak acidic treatment or a mechanical treatment.
  • the asbestos fibres are decomposed by being subjected to a process comprising treating asbestos fibres with an aqueous solution of .ammonium sulfate at a temperature of at least 200 ⁇ C.
  • the process of this particular aspect of the present Invention leads to a substantially total decomposition of the asbestos fibres, even though, in accordance with what is explained above, the presence of a minor amount of fibrous structures in the treated asbestos material may be acceptable. Therefore, as stated above, "decomposed" as used in connection with this particular aspect of the present invention is intended to allow for a minor amount of fibrous structures, pre ⁇ ferably less than about 5% of the total asbestos material as estimated from a microscopic or a X-ray analysis, more preferably less than 2%, still more preferably less than 1%, such as less than 0.1% or in practice zero.
  • U.S. patent No. 3,338,667 (Pundsack) and Danish patent applica ⁇ tion No. 784/80 (Lalancette) disclose the recovery of magnesium com ⁇ pounds from waste material resulting from the production of chryso ⁇ tile asbestos fibres.
  • the waste materials which are commonly termed tailings and floats, are in the form of dust and do not have a fibrous appearance.
  • the tailings and floats are stated not to be use ⁇ ful for any practical application.
  • the magnesium content of the tailings and floats is recovered by reaction with ammonium salts, such as, in the case of the Danish patent application, ammonium sulfate in a dry state, and in the case of the U.S.
  • the above U.S. patent discloses the magnesium recovery from asbestos tailings and floats by reaction with an aqueous solution of ammonium hydrogen sulfate.
  • the asbestos-derived material and the ammonium hydrogen sulfate solution are mixed and heated in a reactor to boil ⁇ ing conditions under reflux for 1/2 hour to 6 hours or more.
  • magnesium sulfate is obtained.
  • the ammoni ⁇ um hydrogen sulfate may be obtained by heating ammonium sulfate to a temperature of about 320°C, whereby the ammonium sulfate is decom ⁇ posed to yield ammonium hydrogen sulfate and ammonia. This ammonium' hydrogen sulfate preparation is not carried out in the reactor.
  • U.S. patent No. 4,335,083 discloses a method for recovery of magnesium compounds from magnesium hydroxide-containing compositions which may be found in connection with chrysotile asbestos fibres.
  • the magnesium is obtained by reacting the asbestos material with an am ⁇ monium salt solution., e.g. of ammonium sulfate, at a temperature of about 100°C.
  • the patent states that the magnesium recovery method improves the acid resistance of the chrysotile fibre, i.e. the op ⁇ posite effect of the aim of the present invention.
  • ammonium hydrogen sulfate * begins at a temperature of about 200 ⁇ C.
  • the reaction takes place according to the reaction scheme below:
  • the extent of the above reaction is dependent on the temperature, i.e. the decomposition increases with increasing temperature. At a temperature of about 260°C, the decomposition can be achieved within 30 min. It has been found that the reaction at this temperature is economically very favourable. At temperatures above about 260°C, the decomposition continues and still increases, but the higher the tem ⁇ perature, the higher the energy demand, and at temperatures above about 320°C, the reaction will be less efficient.
  • reaction scheme is idealized, i.e. other related components than the above stated may be present in the reaction mixture.
  • the efficiency of the decomposi ⁇ tion of the asbestos material may be estimatet by measuring the amount of magnesium ions in the liquid part of the reaction mixture (such as will be understood from the above reaction scheme) and comparing the amount of Mg measured with the amount of Mg in the Initial asbestos fibre containing material.
  • the efficiency of decomposition may, however, also be determined as stated above, e.g. by microscopic or X-ray diffraction investigations of the reaction mixture or by determination of the Mg-content of the solid part of the reaction product.
  • the magnesium based measurements must be regarded as estimates as some of the magnesium ions of the liquid part of the reaction mixture may be bound to various compcunds of the solid part of the reaction mixture and thus mistakenly be assumed to represent non-reacted material.
  • a magnesium content of the solid part of the reaction mixture was determined to be 4% and 2%, respectively, calculated on the weight of the total mixture, even though no fibrous structures could be ob ⁇ served under a microscope.
  • the magnesium ions of the reacted mixture are in solution and may be isolated therefrom in the form of various salts, such as magnesium sulfate.
  • the rate of decomposition of ammonium sulfate is increased with increasing temperature, resulting in an increasing extent of attack of the asbestos fibres.
  • the process of this particular aspect of the present invention is preferably carried out at a temperature of at least 240°C, preferably at a temperature in the range of 250-320 ⁇ C, and in particular at a temperature of about 260°C. It is believed that the mechanisms of the process at these higher temperatures are identical to the above described mechanisms. Thus, the increased temperature merely affects the extent of reaction.
  • an iron-containing compound to the aqueous solution, as this may increase the extent of decomposition of the asbestos fibres.
  • the iron of the iron-containing compound is preferably in the form of a ferrous ion, and an example of a suitable iron-containing compound is ferrous sulfate. It is believed that the ferrous ion is oxidized to Fe 2 0 and that this product in some cases promotes the asbestos fibre decomposition.
  • molecular oxygen may be added to the aqueous solution containing the ferrous ion. The molecular oxygen must be present in a concentration which is sufficient to oxidize the ferrous ion. In most cases the molecular oxygen is supplied In excess.
  • some types of asbestos have a natural iron content which may promote the decomposition of the asbestos by the aqueous ammonium sulfate solution in the same way as added iron.
  • molecular oxygen may be added to the aqueous ammonium sulfate solution so as to transform the iron ions into Fe 2 0 3 .
  • the initial concentration of ammonium sulfate in the aqueous solution is preferably in the range of between 2% and 20%, calculated as g of ammonium sulfate/liter of solution. It has been found that an initial concentration of the aqueous solution of ammonium sulfate in the range of between 5% and 10%, calculated as g of ammonium sulfate/- liter of solution, is especially useful. Thus, by use of ammonium sulfate solutions in a concentration in this range, the decomposition of the asbestos fibres proceeds efficiently, resulting in the achievement of the decomposition of the fibres within a reaction time of a satisfactory duration, such as within 30 min.
  • the asbestos fibres constitute at the most 100 g of fibres/liter of solution when the concentration of the ammonium sul ⁇ fate in the solution is within the above ranges. Particularly good results may be obtained when the concentration of asbestos fibres is at the most 50 g of fibres/liter of solution, preferably at the most about 20 g of fibres/liter. When the concentration of fibres is within the above ranges, a sufficient contact between the ammonium sulfate and the asbestos fibres is obtained, resulting in a satisfac ⁇ tory time of decomposition.
  • the asbestos fibres to be decomposed will often be in admixture with other components. This is the case, for example, when building mate- rials containing asbestos fibres are to be destroyed. It Is not necessary to separate the asbestos fibres from the other components with which they are mixed before the asbestos fibres are subjected to decomposition.
  • one embodiment of the present invention relates to a process wherein the asbestos fibres subjected to treatment are asbestos fibres present in asbestos fibre-containing materials.
  • the efficiency of the reaction depends on the accessibility of the fibres, i.e. the amount of the fibres which are exposed to the ammonium hydrogen sulfate.
  • Very long fibres e.g. fibres of a length greater than 200 mm, have a tendency of lumping together so that part of the fibres are shielded by other fibres. This lump formation in ⁇ creases the reaction time necessary for obtaining a total decomposi ⁇ tion of the fibres.
  • the asbestos fibres to be decomposed are preferably of a maximum length of about 200 mm.
  • maximum length is intended to mean that substantially all of the fibres are shorter than this length, but a minor part, such as less than 5%, may be longer. In most cases, the asbestos fibres are even shorter, e.g. of a maximum length of about 100 mm or a maximum length of about 50 mm.
  • the asbestos fibres or the asbestos fibres of the asbestos fibre-containing material are often of a considerable length, it may be necessary, prior to the treatment by the process according to this particular aspect of the invention, to disintegrate the asbestos fibres or asbestos fibre-containing material to be decomposed, so as to obtain fibres of the above stated maximum lengths, e.g. of about 200 mm, preferably of about 100 mm, more preferably of about 50 mm, and particularly of about 10 mm. Any method of disintegrating the asbestos fibres or the asbestos fibre-containing material may be used. However, for reasons of health the disintegration of the asbestos fibres or the asbestos fibre-- containing material preferably takes place In a liquid.
  • the liquid in which the disintegration takes place is the acid component(s) when being In liquid form, e.g. the aqueous ammonium sulfate solution used to decompose the asbestos fibres.
  • Any equipment which is able to disintegrate the asbestos fibres or the asbestos fibre-containing material may be employed. Among other things, the kind of equipment depends on the composition, the state, and the amount of the material to be disintegrated.
  • an example of an useful disintegrator is a beating machine.
  • the dis ⁇ integrator When the asbestos fibres are in admixture with other substances and only constitute a minor amount of the total material to be disintegrated, which is the case, e.g., In building materials or rubber materials, the dis ⁇ integrator must be of a type suitable to handle these materials. In the case of building materials these are for instance treated in a wet condition in a ball mill.
  • the equipment in which the process according to this particular aspect of the invention is performed may be of any type In which the reaction conditions described above may be established.
  • One type of reactor which-is especially suitable is a pipe reactor, and in the following, the process according to this particular aspect of the invention will be discussed particularly with reference to pipe reactors, although it should be understood that the process is not limited to such reactors.
  • the term "pipe reactor” as used herein is defined as a tubular flow reactor through which a suspension is continuously pumped. The flow of the suspension approaches and is nearly identical to Ideal plug flow, which is defined as an orderly flow wherein no element of the suspension is mixed with any other other element located ahead or behind the element in question.
  • the pipe reactor is also known as a plug flow reactor, a slug flow reactor, a piston flow reactor, a tubular reactor and an unmixed flow reactor.
  • the flow in the pipe reactor is preferably a turbulent flow, i.e. a flow having a Reynolds number well in excess of 5,000, such as a Reynolds number of at least 10,000.
  • the Reynolds number is a parameter which is used as an indication of the flow conditions in question.
  • the Reynolds number is a dimension-less value which is calculated from the diameter (D) of the tube, the speed (V) of the suspension through the tube, the viscosity ( ⁇ ) and the density (/?) of the suspension.
  • the Reynolds number may be expressed as
  • a Reynolds number of above 2,000 is defined as being an indication of a turbulent flow.
  • the Reynolds number of the flow of the suspension treated by the pro ⁇ cess of the invention is preferably at least 20,000, such as at least 30,000, so as to ensure that the reaction conditions are sufficiently vigorous.
  • the reaction conditions in the pipe reactor are preferably adapted so that the holding time of the reactor, i.e. the reactor volume divided by the flow rate, is less than 100 min. , preferably 20-60 min. It has been found that holding times within these limits lead to a time of decomposition of the asbestos fibres which is of a suitable duration.
  • the tube ' of a pipe reactor suited to the process according to this aspect of the invention is conveniently of a diameter in the range of 2.5-10 cm.
  • tubes of a smaller diameter than 2.5 cm it is difficult to obtain a sufficiently turbulent flow of the suspension to be treated, as the drop of pressure in these tubes will be very high.
  • the use of tubes of a diameter of more than 10 cm will be too dangerous in most cases, as a considerable pressure is built up in the tubes. Thus, if such tubes are to be used, extensive safeguards must be established.
  • the capacity of the pipe reactor is dependent on the diameter of the tube of the reactor.
  • the diameter of the tube is often limited within the above stated range, one way of increasing the capacity of the pipe reactor is to construct the pipe reactor of two or more tubes arranged In parallel. This result in an increased flow capacity of the pipe reactor and thus in an possibility of treating increased amounts of asbestos fibre-containing material.
  • a convenient flow rate for the suspension is about 30-300 m/min. , preferably about 60-120 m/min.
  • a preferred pipe reactor for carrying out the process according to this particular aspect of the invention comprises a heating zone In which the asbestos fibre-containing solution is heated to the reacting temperature, a reaction zone and a cooling zone.
  • the asbestos fibres or the asbestos fibre-containing material are mixed with the aqueous, ammonium sulfate solution in a mixer of any suitable type.
  • the mixing is performed at ambient temperature, which will often be about 20 ⁇ C. At this temperature the weakly acidic ammonium sulfate solution will not be able to do any harm to the equipment used, and the equipment may therefore be constructed from materials which are not particularly acid-resistant.
  • inexpensive materials such as conventional steel, may be employed for the mixer.
  • the resulting suspension of asbestos fibres or asbestos fibre-- containing materials in the aqueous ammonium sulfate solution is transferred to the pipe reactors, where it is subjected to heating in a heating zone of the pipe reactor.
  • the heating zone comprises a heat transfer zone in which the asbestos fibre-containing solution entering into the system is heated by heat transfer with the effluent in the cooling zone of the pipe reactor.
  • the effluent i.e. the reacted suspension consisting of non-fibrous material, has a high temperature, such as about 250°C. This effluent may advan ⁇ tageously be used to heat the solution which enters into the system.
  • the construction material of the pipe reactor zones which are subjected to temperatures of 200°C or above, must be a material having higher resistance to acidic corrosion than ordinary steel, such as acid-resistant steel.
  • acid-resistant steel a material having higher resistance to acidic corrosion than ordinary steel, such as acid-resistant steel.
  • corrosion inhibitors such as iron corrosion in ⁇ hibitors, so as to make the steel more acid-resistant, will generally not be preferred in connection with the process according to this particular aspect of the invention, as experiments have shown that these inhibitors also inhibit the decomposition of the asbestos fibres.
  • the construction material employed is of a type which does not disturb the asbestos fibre decomposition.
  • this part of the heating zone will not contain any ammonium hydrogen sulfate and may therefore be constructed from the same inexpensive materials as mentioned above. Thus, only the last part of the heating zone must be constructed from more expensive acid-resistant materials.
  • the decomposition of the asbestos fibres is obtained.
  • the part of the reactor constituting the reaction zone must necessarily be made from acid-resistant steel.
  • the holding time in the reaction zone must be of a duration sufficient to ensure that substantially all of the as- bestos fibres are decomposed. Among other things, the holding time will depend on the diameter of the reactor as discussed above.
  • the suspension enters the cooling zone.
  • a part of this cooling zone is placed in connection with the heating zone, such as In a counterflow posi ⁇ tion with the heating zone.
  • the counterflow position may be obtained by two concentrically arranged tubes, ' wherein the cold suspension flows in one of the tubes, and the warm suspension flows in the other tube. Through this arrangement, heat from the warmer reacted suspen- sion is transferred to the colder non-reacted suspension. Cooling the reacted mixture makes it easier to handle.
  • the cooled reacted mixture composed mainly of silicic acid gel and various magnesium salts in solution, may be discharged as such, e.g. by letting the aqueous mixture enter into the sewage system or into another suitable place, such as the sea. This is acceptable from an environmental point of view, as the reacted mixture does not contain any environmentally hazardous components.
  • the magnesium may be recovered from the reacted mixture, e.g. by precipitating the magnesium in the form of a suitable salt, e.g. as a carbonate or a phosphate.
  • the magnesium may be recovered in the form of magne ⁇ sium hydroxide, which is precipitated from the reacted mixture in the presence of the ammonia which has been formed by the process.
  • the magnesium content of the reacted mixture is very low as the concentration of asbestos fibres in the starting materials may be very low.
  • the magnesium content of the mixture may be Increased, result- ing in a more economical recovery of the magnesium.
  • Fig.l is a schematic illustration of a system suitable for asbestos fibre decomposition, especially for treatment of the asbestos fibres with an aqueuos ammonium sulfate solution at a temperature above 200°C,
  • Fig. 2 is a photo of a bundle of non-treated chrysotile asbestos stained with 1% of iodine in glycerine at a magnification of 100,
  • Fig. 3 is a photo of a reaction product resulting from treatment of asbestos fibres according to the present -invention, which product is stained with crystal violet, at a magnification of 100.
  • Fig. 1 is a schematic illustration of a system suitable for asbestos fibre decomposition according to the special aspect of the present invention in which the asbestos fibres are treated with aqueous ammonium sulfate at a temperature of above 200°C.
  • the starting materials comprising an aqueous ammonium sulfate solution and asbestos fibres or asbestos fibre-containing material and, op- tionally, iron-containing compounds, are mixed in a container 1 which may be of any convenient type or size suited to the materials to be mixed.
  • the resulting suspension is pumped by means of a piston membrane pump 2 through a tube 3, which may be of conventional steel, and into a pipe reactor 5.
  • An air vessel 4 ensures that expansion of the suspension is rendered possible.
  • the first part 5a of the pipe reactor consists of two concentrically arranged tubes in which the inflowing cold suspension is passed in either of the tubes in counterflow with the heated effluent suspension present in the other tube. Thereby heat is exchanged between the two flows.
  • molecular oxygen is supplied to the suspension, this is preferably in the form of pure oxygen obtained from an oxygen flask 6 or a compressor system 7.
  • the molecular oxygen is passed into the system in a central part 5b of the pipe reactor 5.
  • the first two parts 5a and 5b of the pipe reactor 5 constitute the heating zone. Additional heat in the form of saturated water vapour generated by a heating system 8 is supplied to the heating jacket of a third part 5c of the pipe reactor.
  • This third part 5c of the pipe reactor constitutes the reaction zone wherein the decomposition of the asbestos fibres or the asbestos fibre-containing material is performed.
  • the mixture is passed through a cooling zone 10 of the pipe reactor and back to the first part 5a of the pipe reactor wherein the heat is exchanged with the inflowing suspension.
  • the reacted mixture leaves the autoclave via a tubing 11 and is either discharged or collected for further treatment.
  • the experiments were performed in a pilot autoclave made of acid-- resistant steel of the type UBH24, available from Avesta, Sweden, and consisting of a steel container in the form of a cylinder having an inner diameter of about 11 cm and a height of 18 cm and a 160 cm long steel tube with an inner diameter of 22 mm forming a closed loop.
  • a steel container in the form of a cylinder having an inner diameter of about 11 cm and a height of 18 cm and a 160 cm long steel tube with an inner diameter of 22 mm forming a closed loop.
  • One end of the tube was welded to the outside of the bottom of the container, and the other end was welded to the outside of the lower part of the side of the container.
  • a centrifugal pump wheel was arranged which created the flow of the suspension to be treated through the closed autoclave system comprising the tube and the cylinder.
  • the pump wheel was driven by an electric motor via a magnetic coupling, the electric motor being arranged outside the autoclave.
  • the top of the container was constituted by a lid which was closed by a flange assembly.
  • the lid was equipped with an inlet valve for molecular oxygen.
  • the suspension to be treated in the autoclave was added to the container by removing the lid and simply pouring the suspension into the container.
  • the reacted suspension was withdrawn from the autoclave by means of a vacuum pump.
  • the volume of the suspension in each of the following examples was about half of the total volume of the autoclave.
  • the remaining free volume of the autoclave was filled with atmospheric air, or optionally with molecular oxygen.
  • the autoclave was constructed so as to obtain reaction conditions in the tube very similar to plug flow conditions.
  • the flow rate was about 1 liter/sec. , resulting in a Reynolds number of about 30,000.
  • the viscosity of the suspensions of the following examples is dependant on the type of components present in the suspensions, the flow rate and the Reynolds number may differ from those of pure water. It has not been possible to measure the exact flow rate of the suspensions used in the examples as such measurements would disturb the reaction, but it was evident that the flow was turbulent, i.e. of a Reynolds number well in excess of 10,000.
  • the autoclave was heated by being dipped in a thermostated melted salt bath and cooled by being dipped in cold water. With respect to heating, the desired temperature was reached in about 5 min. and with respect to cooling the temperature was reached in about 2 min.
  • the temperature of the autoclave was kept at 260°C, resulting in a pressure of about 60 bars.
  • the autoclave was not equipped with a pressure gauge, so the pressure was estimated on the basis of the vapour pressure of the oxygen and ammonia contents of the autoclave.
  • ammonium sulfate solution employed in the experiments was of a concentration of 10% calculated as g/liter.
  • the ammonium sulfate was of analytical grade and supplied by Merck.
  • 0.7 g of the sliced chrysotile and 1 liter of 10% (NH ) 2 S0 were mixed in a beaker and the resulting suspension was poured into the autoclave and reacted for 20 min. at 260°C.
  • the resulting reacted suspension smelt of ammonia and had a red colour, owing to the presence of colloidal Fe 0 3 , which presumably stems from the iron contained in the mineral. Microscopic analysis of the resulting suspension showed numerous particles, but no fibres were observed.
  • Asbestos cloth was unravelled and cut into pieces of about 5 mm transversly to the fibre direction.
  • 2.23 g of the resulting asbestos pieces were mixed with 1 liter of 10% (NH 4 ) 2 S0 4 in a beaker and the resulting suspension was poured into the autoclave and reacted for 20 min. at 260°C.
  • the resulting suspension which was red and smelt of ammonia like the suspension of Example 1, was filtered, and the solid residue was analyzed by X-ray diffraction.
  • X-ray analysed mineral chrysotile of the same batch as the one used in Ex- ample 1 it was found that about 2% of the chrysotile structure of the asbestos cloth was preserved.
  • the chrysotile structure could not be observed under a microscope.
  • the suspension was pumped out of the autoclave, less than 2% non-reacted asbestos material, based on the weight of the starting material, was found in the wheel of the pump. It is presumed that at least part of the chrysotile structures which were observed by the X-ray analysis were constituted by the non-reacted asbestos material which had been collected in the wheel of the pump and later on, when the decomposition of the suspension was nearly terminated, had been lost from the wheel of the pump and dispersed throughout the suspension. The reason why the chrysotile structure was not observed by the microscopic analysis Is presumably the low fibre concentration and the small size of the fibres.
  • the material to be treated contained rather long and coarse asbestos fibres which were in intimate mixture with a fine powder and with short straight fibres, presumably of glass or rockwool origin.
  • the fine powder was not analyzed, but could be moler or kieselguhr.
  • the amount of asbestos fibres in the material was determined by sieve analysis using a 1.3 mm sieve which retained the asbestos fibres and let the rest of the material pass. It was found that 100 g of the material contained 4.5 g of asbestos fibres. 50 g of the material, comprising about 2.25 g of asbestos fibres was mixed with 1 liter of 10% (NH 4 ) 2 S0 4 and reacted in the autoclave in the presence of 6 ato
  • Asbestos cloth but of another make than in Example 2, was unravelled and torn in a wet condition for 1 min. in a high-powered kitchen blender (Braun MX32) at the maximum speed of the blender, resulting in fibres, of which the main part was of a length of about 2-5 mm. 7g of the torn material was mixed with 1 liter of 10% (NH 4 ) 2 S0 4 and reacted in the autoclave in the presence of 6 ato 0 2 for 30 min. at a temperature of 260°C. When it was takeri out of the autoclave, the suspension was not red, so the asbestos has apparently not contained iron to any great extent.
  • the suspension contained fine needle-shaped threads of a length of about 0.1 mm, as determined by microscopic analysis.
  • the threads were not analyzed by X-ray diffraction, but might be of asbestos origin and constituted of a non-reacted remnant of material which, as in Example 2, was found in the pump wheel.
  • Mg Mg compared to 19.8% in the starting material.
  • the content of Mg was determined by atomic absorption analysis, performed on an atomic absorption spectrophotometer of the type Perkin-Elmer 603.
  • the degree of decomposition of chrysotile at pH-values of about 1, 2 and 3 was investigated in a series of experiments.
  • a mixture of 1.00 g of chrysotile and 200 ml of water was mixed and stirred for 1 minute in the blender used in Example 4, and the resulting suspension was transferred to a beaker, in which it was subjected to magnetic stirring.
  • the pH of the suspension was adjusted to the desired pH-value by means of a pH-stat by addition of 0.1 or 1.0 N H 2 S0 .
  • the beaker was placed on a shake board which was set on 100 r.p.m.
  • the pH of the suspension was manually controlled, and it was attempted to keep the pH at the desired value.
  • Table 1 considerably variations of the pH occurred, and the pH was generally slightly higher than the pH value which was aimed at.
  • reaction mixture was analyzed throughout the reaction period. Thus, samples of the liquid part of reaction mixture were taken and analyzed for their content of magnesium by use of an atomic absorp ⁇ tion spectophotometer of the type Perkin-Elmer 603. At the termina- tion of each of the experiments, the reaction mixture was filtrated and the magnesium content of the residue was determined. Also the residue was examined by X-ray diffraction.
  • time indicates the time after the start of the experiment, i.e.
  • ml H 2 S0 indicates the amount of H 2 S0 4 added and in this context, the normality of the H S0 employed is also stated, “total ml” indicates the total volume of the suspension, and “ppm mg” indicates the content of Mg in the liquid.
  • the Mg-content of the residue was found to be 0.33% compared to a Mg- content of the starting asbestos fibres of about 20%. This corre ⁇ sponds to a degree of decomposition of 98.4%.
  • Table 1 show, that the Mg-content of the liquid part of the reaction product increases with time, which is an indication of the increasing dissolution of the asbestos fibrous structure. The experiment was terminated after 47 days and a higher degree of decomposition could probably be obtained by extending the reaction period. No_ chrysotile structure was observed by X-ray diffraction analysis.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Inorganic Chemistry (AREA)
  • Environmental & Geological Engineering (AREA)
  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Processing Of Solid Wastes (AREA)

Abstract

On décompose et on élimine des fibres d'amiante, telles que notamment des fibres minérales de chrysotile, en les faisant réagir avec un composant acide, tel que de l'acide sulphurique. On effectue la réaction à un pH inférieur à 5 pendant une période (allant par exemple jusqu'à plusieurs semaines ou mois) suffisante pour obtenir une décomposition totale des fibres. On peut accélérer la réaction en la soumettant à une température d'échauffement, comprise par exemple entre 5 et 100°C, et/ou à un traitement physique. On peut effectuer la décomposition en continu ou par lots. On peut également décomposer les fibres d'amiante par réaction avec une solution aqueuse de sulfate d'ammonium à une température supérieure à 200°C, se situant de préférence autour de 260°C. La réaction au sulfate d'ammonium est effectuée dans un autoclave, ayant par exemple la forme d'un réacteur à tube ou réacteur tubulaire, dans lequel la suspension des fibres d'amiante et du sulfate d'ammonium est soumise à un écoulement tourbillonnaire, c'est-à-dire présentant un nombre de Reynolds supérieur à 2000 et la réaction est généralement menée à terme en 30 minutes. Le magnésium qui est libéré de l'amiante pendant le traitement peut être récupéré.
PCT/DK1988/000105 1987-06-26 1988-06-27 Procede de traitement de l'amiante WO1988010234A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DK329887A DK329887D0 (da) 1987-06-26 1987-06-26 Fremgangsmaade til behandling af asbest
DK3298/87 1987-06-26

Publications (1)

Publication Number Publication Date
WO1988010234A1 true WO1988010234A1 (fr) 1988-12-29

Family

ID=8121346

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DK1988/000105 WO1988010234A1 (fr) 1987-06-26 1988-06-27 Procede de traitement de l'amiante

Country Status (3)

Country Link
AU (1) AU1989388A (fr)
DK (1) DK329887D0 (fr)
WO (1) WO1988010234A1 (fr)

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1991000123A1 (fr) * 1989-06-29 1991-01-10 Ek Roger B Transformation mineralogique de deches d'amiante
EP0546984A1 (fr) * 1991-12-04 1993-06-16 SOLVAY UMWELTCHEMIE GmbH Décomposition semi-continue d'amiante
EP0557915A1 (fr) * 1992-02-28 1993-09-01 Solvay Umweltchemie GmbH Procédé pour l'élimination d'amiante contaminée par la radioactivité
WO1993018867A1 (fr) * 1992-03-23 1993-09-30 Lemmerbrock, Karl-Heinrich Procede d'elimination de l'amiante ou de matieres contenant de l'amiante
US5516973A (en) * 1990-04-13 1996-05-14 Austin-Chase Industries, Inc. Method for treating asbestos
US6160195A (en) * 1999-01-22 2000-12-12 Brookhaven Science Associates Use of reagents to convert chrysotile and amosite asbestos used as insulation or protection for metal surfaces
WO2006052859A2 (fr) * 2004-11-08 2006-05-18 352 East Irvin Avenue Limited Partnership Traitement sur place de materiau contenant de l'amiante
JP2008272577A (ja) * 2007-01-30 2008-11-13 Konoshima Chemical Co Ltd アスベスト無害化方法およびその方法で製造された肥料
EP2067539A1 (fr) * 2006-09-29 2009-06-10 K.K.M.-Tec Procédé de traitement de l'amiante
FR2930736A1 (fr) * 2008-04-30 2009-11-06 Centre Nat Rech Scient Traitement acide sous faibles temperature et pression d'un dechet contenant de l'amiante
FR2951967A1 (fr) * 2009-11-05 2011-05-06 Centre Nat Rech Scient Destruction d'amiante avec synthese conjointe de rhabdophane
FR2951968A1 (fr) * 2009-11-05 2011-05-06 Centre Nat Rech Scient Conversion d'amiante ciment en un materiau solide a base de silice amorphe
ITLI20120012A1 (it) * 2012-10-31 2014-05-01 Paolo Berni Processo di inertizzazione dell'amianto mediante trattamento fisico chimico, con particolare riferimento ai manufatti in fibrocemento con riutilizzo dei sottoprodotti inerti ottenuti.
WO2017051117A1 (fr) * 2015-09-22 2017-03-30 Paul Poggi Procédé et dispositif fixe ou mobile de neutralisation et valorisation de déchets d'amiante
WO2019038502A1 (fr) * 2017-08-24 2019-02-28 Université De Montpellier Procédé de destruction et de valorisation de déchets amiantés

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2402370A (en) * 1942-06-20 1946-06-18 Henry B Chalmers Method of producing magnesium compounds
DE1567517A1 (de) * 1965-03-01 1970-04-16 Fmc Corp Verfahren zur Herstellung eines mikrokristallinen,kolloidalen Materials aus Chrysotil
US3708014A (en) * 1971-06-23 1973-01-02 Phillips Petroleum Co Hydrochloric acid/hydrofluoric acid treatment to remove asbestos fibers from a well bore
GB1342102A (en) * 1970-01-08 1973-12-25 Huber O Chrysotile asbestos sorption agents
US4058587A (en) * 1973-05-24 1977-11-15 Ernest William Nelson Process for removing impurities from acidic fluid solutions
US4335083A (en) * 1981-03-05 1982-06-15 Carey Canada Inc. Method for leaching magnesium from magnesium hydroxide-containing composition

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2402370A (en) * 1942-06-20 1946-06-18 Henry B Chalmers Method of producing magnesium compounds
DE1567517A1 (de) * 1965-03-01 1970-04-16 Fmc Corp Verfahren zur Herstellung eines mikrokristallinen,kolloidalen Materials aus Chrysotil
GB1342102A (en) * 1970-01-08 1973-12-25 Huber O Chrysotile asbestos sorption agents
US3708014A (en) * 1971-06-23 1973-01-02 Phillips Petroleum Co Hydrochloric acid/hydrofluoric acid treatment to remove asbestos fibers from a well bore
US4058587A (en) * 1973-05-24 1977-11-15 Ernest William Nelson Process for removing impurities from acidic fluid solutions
US4335083A (en) * 1981-03-05 1982-06-15 Carey Canada Inc. Method for leaching magnesium from magnesium hydroxide-containing composition

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
CHEMICAL ABSTRACT, Vol. 74 (1971), abstract No. 6103k. *

Cited By (32)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1991000123A1 (fr) * 1989-06-29 1991-01-10 Ek Roger B Transformation mineralogique de deches d'amiante
US5516973A (en) * 1990-04-13 1996-05-14 Austin-Chase Industries, Inc. Method for treating asbestos
EP0546984A1 (fr) * 1991-12-04 1993-06-16 SOLVAY UMWELTCHEMIE GmbH Décomposition semi-continue d'amiante
EP0557915A1 (fr) * 1992-02-28 1993-09-01 Solvay Umweltchemie GmbH Procédé pour l'élimination d'amiante contaminée par la radioactivité
WO1993018867A1 (fr) * 1992-03-23 1993-09-30 Lemmerbrock, Karl-Heinrich Procede d'elimination de l'amiante ou de matieres contenant de l'amiante
LT3092B (en) 1992-03-23 1994-11-25 Lemmerbrock Karl Heinrich Method for destroying asbestos or asbestic materials
US5562585A (en) * 1992-03-23 1996-10-08 Karl-Heinrich Lemmerbrock Process for disposal of asbestos or substances containing it
US6160195A (en) * 1999-01-22 2000-12-12 Brookhaven Science Associates Use of reagents to convert chrysotile and amosite asbestos used as insulation or protection for metal surfaces
WO2006052859A2 (fr) * 2004-11-08 2006-05-18 352 East Irvin Avenue Limited Partnership Traitement sur place de materiau contenant de l'amiante
WO2006052859A3 (fr) * 2004-11-08 2006-07-27 352 East Irvin Avenue Ltd Part Traitement sur place de materiau contenant de l'amiante
EP2067539A1 (fr) * 2006-09-29 2009-06-10 K.K.M.-Tec Procédé de traitement de l'amiante
EP2067539A4 (fr) * 2006-09-29 2013-02-27 M Tec Kk Procédé de traitement de l'amiante
JP2008272577A (ja) * 2007-01-30 2008-11-13 Konoshima Chemical Co Ltd アスベスト無害化方法およびその方法で製造された肥料
FR2930736A1 (fr) * 2008-04-30 2009-11-06 Centre Nat Rech Scient Traitement acide sous faibles temperature et pression d'un dechet contenant de l'amiante
WO2009138704A3 (fr) * 2008-04-30 2010-06-03 Centre National De La Recherche Scientifique (C.N.R.S) Traitement acide sous faibles température et pression d'un déchet contenant de l'amiante
US20110101267A1 (en) * 2008-04-30 2011-05-05 Institut National Polytechnique De Toulouse Acid treatment under low temperature and pressure of waste containing asbestos
FR2951968A1 (fr) * 2009-11-05 2011-05-06 Centre Nat Rech Scient Conversion d'amiante ciment en un materiau solide a base de silice amorphe
WO2011055093A3 (fr) * 2009-11-05 2011-06-30 Centre National De La Recherche Scientifique (C.N.R.S) Conversion d'amiante ciment en un matériau solide à base de silice amorphe
WO2011055095A3 (fr) * 2009-11-05 2011-09-15 Centre National De La Recherche Scientifique (C.N.R.S) Destruction d'amiante avec synthèse conjointe de rhabdophane
FR2951967A1 (fr) * 2009-11-05 2011-05-06 Centre Nat Rech Scient Destruction d'amiante avec synthese conjointe de rhabdophane
ITLI20120012A1 (it) * 2012-10-31 2014-05-01 Paolo Berni Processo di inertizzazione dell'amianto mediante trattamento fisico chimico, con particolare riferimento ai manufatti in fibrocemento con riutilizzo dei sottoprodotti inerti ottenuti.
AU2016325507B2 (en) * 2014-09-22 2021-09-30 Black Asbestos Ltd Method and stationary or movable device for neutralizing and recycling asbestos waste
CN108290186B (zh) * 2015-09-22 2021-07-30 P·颇纪 中和与再利用石棉废料的移动或固定方法与设备
CN108290186A (zh) * 2015-09-22 2018-07-17 P·颇纪 中和与再利用石棉废料的移动或固定方法与设备
WO2017051117A1 (fr) * 2015-09-22 2017-03-30 Paul Poggi Procédé et dispositif fixe ou mobile de neutralisation et valorisation de déchets d'amiante
US11331526B2 (en) 2015-09-22 2022-05-17 Paul Poggi Method and stationary or movable device for neutralizing and recycling asbestos waste
IL258221B (en) * 2015-09-22 2022-12-01 Paul Poggi Stationary or mobile method and device for neutralizing and recycling asbestos waste
IL258221B2 (en) * 2015-09-22 2023-04-01 Paul Poggi Stationary or mobile method and device for neutralizing and recycling asbestos waste
WO2019038502A1 (fr) * 2017-08-24 2019-02-28 Université De Montpellier Procédé de destruction et de valorisation de déchets amiantés
FR3070282A1 (fr) * 2017-08-24 2019-03-01 Universite De Montpellier Procede de destruction et de valorisation de dechets amiantes
CN111107950A (zh) * 2017-08-24 2020-05-05 蒙彼利埃大学 石棉废物销毁和增值方法
US11577112B2 (en) 2017-08-24 2023-02-14 Université De Montpellier Asbestos waste destruction and valorization method

Also Published As

Publication number Publication date
AU1989388A (en) 1989-01-19
DK329887D0 (da) 1987-06-26

Similar Documents

Publication Publication Date Title
WO1988010234A1 (fr) Procede de traitement de l'amiante
US4566986A (en) Flocculating agents and processes for making them
CN100451182C (zh) 一种非金属材料硫酸钙晶须的制备方法
Licong et al. Reactive crystallization of calcium sulfate dihydrate from acidic wastewater and lime
US20020185456A1 (en) Treatment of sewage sludge
CN1085192A (zh) 复合高效水质净化剂的制备及其应用
CN110304646A (zh) 一种从铝灰中高效分离氟、氯、氮成分联产氧化铝精矿的方法
KR20160065867A (ko) 금속을 처리하는 방법
CN110304703A (zh) 一种用铝灰生产聚氯化铝净水剂的制备方法
WO2011038167A1 (fr) Prévention ou réduction du tartre dans la production d'acide phosphorique par voie humide
CN86100031A (zh) 含钙的钨矿物料的处理方法
CN1254023A (zh) 一种从含钒矿石焙烧料中提钒的浸出方法以及在石煤空白焙烧－直接浸取提钒工艺中的应用
CN104928752B (zh) 一种常温制备二水硫酸钙晶须及其常压转无水晶须的方法
AU2009207898B8 (en) Process for recycling spent pot linings (SPL) from primary aluminium production
CA1077798A (fr) Mode de preparation d'un floculant inorganique
CN109761397A (zh) 一种去除生化出水中总有机碳和苯系物的方法和装置
Şengi̇l The utilization of alunite ore as a coagulant aid
EP3988202A1 (fr) Matériau de purification d'eau contenant du fer en tant que composant principal, et son procédé de fabrication
EP1328357A1 (fr) Procede de traitement des cendres residuelles provenant d'usines d'incineration de dechets
JPH02111407A (ja) 廃液の処理方法
CS216522B2 (en) Method of cleaning the waste waters containing dissolved organic impurities
US3944687A (en) Method of preparing purifying agents consisting of activated siliceous porous mineral substances
US2643226A (en) Water fluoridation and impurity coagulation
CN112044408A (zh) 一种磁性竹纤维及其制备工艺
Boncukcuoğlu et al. Borax production from borax slime, an industrial waste

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AT AU BB BG BR CH DE DK FI GB HU JP KP KR LK LU MC MG MW NL NO RO SD SE SU US

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE BJ CF CG CH CM DE FR GA GB IT LU ML MR NL SE SN TD TG

REG Reference to national code

Ref country code: DE

Ref legal event code: 8642