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
  • A62D3/33—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances by reacting with chemical agents by chemical fixing the harmful substance, e.g. by chelation or complexation
• • 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
  • A62D2101/08—Toxic combustion residues, e.g. toxic substances contained in fly ash from waste incineration
• • 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
  • A62D2101/43—Inorganic substances containing heavy metals, in the bonded or free state

Definitions

• the present invention relates to a waste-treating material and a method for treating waste, which are effective for stabilizing harmful metals contained in the waste which contains a calcium compound such as calcium hydroxide, calcium oxide or calcium chloride. More particularly, the invention relates to a waste-treating material and a method for treating waste, which are effective for stabilization treating harmful metals such as Pb in waste incineration fly ash which contains a calcium compound such as calcium hydroxide, calcium oxide or calcium chloride, and is difficult to suppress elution of lead (Pb).
• a waste-treating material and a method for treating waste which are effective for stabilizing harmful metals contained in the waste which contains a calcium compound such as calcium hydroxide, calcium oxide or calcium chloride.
• a method for stabilization is used wherein a cement is used as a treating material, the cement and the waste are mixed, water is added to the mixture and kneaded, and the resulting kneaded mixture is aged and solidified, thereby preventing elution of harmful metals.
• the conventional treatment method of industrial waste of simply solidifying the same with the cement involves various problems, and unless the purpose of use is limited, secondary pollution may possibly induce.
• slaked lime is blown for the purpose of suppressing an amount of hydrogen chloride gas generated during operation, resulting in forming an alkali atmosphere.
• JP-A-53-6270 discloses a method of treating waste using a water glass and hydrogen carbonate in treatment of lime cake discharged from sugar refining or sugar refining factory.
• the hydrogen carbonate acts to water glass as an acid, if a mixture of those is prepared before use, water glass gels, and it cannot be used as one part treating material.
• an object of the present invention is to provide a waste-treating material and a method for treating waste, which can stabilize various harmful metals contained in the waste containing calcium compounds such as calcium hydroxide, calcium oxide or calcium chloride so as not to re-elute those by surely solidifying those.
• the present inventors have made extensive investigations to overcome the problems involved in the prior art and have developed a method for treating waste using a water glass.
• This method is a method for preventing elution of harmful metals in waste by mixing the waste containing calcium compounds such as calcium hydroxide, calcium oxide or calcium chloride with a water glass.
• the present invention has reached to obtain a new method for treating waste which can achieve the above object more surely.
• a first waste-treating material according to the present invention in order to achieve the above object comprises a water glass aqueous solution and at least one selected from the group consisting of the following additive A and additive B, as main structural components.
• the additive A herein is at least one selected from the group consisting of acids, alcohols, polyvalent metal salts, polyhydric alcohol esters, carbonates, intramolecular esters, dibasic acid esters and dialdehydes.
• the additive B herein is at least one selected from the group consisting of materials which form calcium compounds which are insoluble or sparingly soluble in water by reacting with calcium ions, and ion sealing agents which seal calcium ions.
• a second waste-treating material according to the present invention comprises a treating material comprising a water glass aqueous solution as the main structural component, and an additive C comprising a coagulating sedimentator, added to the treating material.
• a third waste-treating material according to the present invention comprises a treating material comprising a water glass aqueous solution as the main structural component, and an additive D comprising at least one selected from the group consisting of monovalent metal salts and ammonium salts, which do not produce calcium compounds which are insoluble or sparingly soluble in water by reacting with calcium ions, added to the treating material.
• the method for treating waste according to the present invention comprises kneading the waste and the above-described waste-treating material, and aging the resulting mixture.
• the water glass aqueous solution used in the present invention may be a glass water aqueous solution for general purpose.
• an alkali component of the water glass include Na, K and ammonia.
• Na, i.e., sodium silicate (Na 2 O ⁇ nSiO 2 ) is preferred from the viewpoints of stabilization performance of harmful heavy metals and the like, industrial availability, cost, and the like.
• the water glass aqueous solution is represented by M 2 O ⁇ nSiO 2 , and n (SiO 2 /M 2 O compositional ratio) is in the range of about 0.5 to 4.2 in the commercially available product. When n is 2.0 or more, the performance for preventing elution of harmful heavy metals is excellent.
• n is less than 2.0, stability in an aqueous solution is poor, and solid component in an water glass aqueous solution may precipitate depending on the storage condition at a low temperature in the season of winter. From this, it is generally preferred to use a water glass aqueous solution defined by JIS (Japanese Industrial Standard). Further, there is no problem even if the glass water aqueous solution used in the present invention contains unavoidable impurities such as iron.
• the performance for stabilizing harmful metals in the water glass aqueous solution is developed by sealing of harmful metals, adsorption of harmful metals on a gel produced, and the like by a gelation reaction of calcium ions and the like eluted from the waste with polyvalent metal ions, but depending on the amount of polyvalent metal ions such as calcium ions, the effect may sufficiently develop or may not sufficiently develop.
• the gel produced by the reaction of the water glass aqueous solution with calcium ions takes a different form depending on the amount of calcium ions, and the difference in the form affects sealing and adsorption actions of harmful metals.
• the additive A added to the water glass aqueous solution in the treating material is that acids, alcohols, polyvalent metal salts, polyhydric alcohol esters, carbonates, intramolecular esters, dibasic acid esters, dialdehydes, and the like are reacted with the water glass aqueous solution, and solid component monomers in the water glass aqueous solution are partially polymerized, so that the water glass solid component is polymerized.
• the polymerized water glass gels by merely reacting with a slight amount of calcium compounds, and further solidifies by aging. As a result, reaction rate between water glass and calcium compounds in the waste is increased, and the action for sealing and solidifying harmful metals such as Pb is accelerated.
• the additive B in the treating material reacts with calcium ions to form the calcium compounds which are insoluble or sparingly soluble in water, or to seal the calcium ions, thereby the relationship in the amount between the water glass aqueous solution and the calcium ions can be made optimum.
• the additive B is added to the waste-treating material to appropriately control so as to decrease the amount of calcium ions, and this enables the performance for stabilizing harmful metals by the water glass aqueous solution to markedly improve.
• the additive C comprising a coagulating sedimentator
• the treating material comprising the water glass aqueous solution as the main structural component
• fine particles which constitute the waste are coagulated to decrease a contact area with water, making it difficult to elute harmful heavy metals, and also since a gel of the water glass, produced by the reaction with polyvalent metal ions such as calcium ions, includes and seals the coagulated particles, the effect for preventing elution of heavy metals is further improved. It is further considered that even if heavy metals are eluted, the produced water glass gel adsorbs eluted ions, thereby preventing reelution.
• the performance for stabilizing harmful metals of the water glass aqueous solution is developed by sealing of harmful metals involved in gelation reaction of the water glass aqueous solution with polyvalent metal ions such as calcium ions eluted from the waste.
• polyvalent metal ions such as calcium ions eluted from the waste.
• the third treating material of the present invention comprises a treating material comprising a water glass aqueous solution as the main structural component, and the additive D comprising at least one of monovalent metal salts and ammonium salts, added to the treating material. Therefore, ion concentration in the aqueous solution of the treating material increases by monovalent metal ions or ammonium ions released from the additive D, and by the salting out effect, the solid component of the water glass aqueous solution is liable to precipitate. As a result, it is considered that a gel production rate when the water glass in the treating material aqueous solution reacts with polyvalent metal ions such as calcium ions in fly ash becomes fast, and the performance for stabilizing Pb is improved.
• waste-treating material of the present invention is described in more detail below.
• the acid is added in an amount such that hydrogen ion (H + ) released from the acid exceeds 50 parts by mol per 100 parts by mol of cations in the water glass aqueous solution (where water glass is sodium silicate, cation is replaced by sodium, and hereinafter the same), its pH reaches a neutral region.
• the treating material may gel instantaneously or after several minutes.
• the treating material gelled can be expected to be a certain degree of the performance for stabilizing Pb, but such a performance is not sufficient.
• the gelled treating material is in the form which cannot be used as a liquid treating material, and this may possibly induce undesirable problems such as clogging of pipings of an injection device for the treating material, a kneader of the waste and the treating material, and the like.
• the amount of the acid added is preferably such that the hydrogen ion (H + ) in the acid is 50 parts by mol or less per 100 parts by mol of cations in the water glass aqueous solution.
• any acid can be used as the acid so long as it ionizes in water or the water glass aqueous solution to release hydrogen ion (H + ).
• the acid which can be used include hydrochloric acid (HCl), nitric acid (HNO 3 ), phosphinic acid (HPH 2 O 2 ), phosphonic acid (H 2 PHO 2 ), phosphoric acid (H 3 PO 4 ), diphosphoric acid (H 4 P 2 O 7 ), tripolyphosphoric acid (H 5 P 3 O 10 ), sulfurous acid (H 2 SO 3 ), sulfuric acid (H 2 SO 4 ), carbonic acid (H 2 CO 3 ), monochloroacetic acid (CH 2 ClCOOH), dichloroacetic acid (CHCl 2 COOH), trichloroacetic acid (CCl 2 COOH), acetic acid (CH 3 COOH), citric acid ((OH)C 3 H 4 (COOH) 3 ⁇ H 2 O), adipic acid ((CH 2 ) 4 (COOH)
• hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, carbonic acid, acetic acid and oxalic acid are preferred, considering industrial availability, the cost, the performance for stabilizing Pb, and the like. If necessary, two or more of different kinds of acids can be used together.
• the polyvalent metal salt is added in an amount such that the product of the part by mol of polyvalent metal ions in the polyvalent metal salts and its number of valency exceeds 50 parts by mol per 100 parts by mol of cations in the water glass aqueous solution, it is an amount such that metal ions make the treating material gel instantaneously or after several minutes.
• the gelled treating material may have the same disadvantages as described before, and is undesirable. From this reason, the amount of the polyvalent metal salts added is preferably such that the product of the part by mol of polyvalent metal ions of the polyvalent metal salts and its number of valency is 50 parts by mol or less per 100 parts by mol of cations in the water glass aqueous solution.
• Examples of the polyvalent metal salts include chlorides, nitrates, sulfates, carbonates and phosphates of magnesium, calcium, strontium, barium, iron, aluminum and zinc. Specific examples thereof include magnesium chloride (MgCl 2 ), calcium chloride (CaCl 2 ), strontium chloride (SrCl 2 ), barium chloride (BaCl 2 ), iron (II) chloride (FeCl 2 ), iron (III) chloride (FeCl 3 ), zinc chloride (ZnCl 2 ), aluminum chloride (AlCl 2 ), magnesium nitrate (Mg(NO 3 ) 2 ), calcium nitrate (Ca(NO 3 ) 2 ), strontium nitrate (Sr(NO 3 ) 2 ), barium nitrate (Ba(NO 3 ) 2 , iron (II) nitrate (Fe(NO 3 ) 2 ), iron (III) nitrate (Fe(NO 3 )
• the treating material comprising the water glass and the polyvalent metal salts, as the main structural components exhibits the performance for stabilizing the desired harmful metals, it is necessary that the polyvalent metal salts rapidly dissolve in water or the water glass aqueous solution to react with water glass, and the solid component of the water glass is polymerized.
• the preferred polyvalent metal salts are magnesium chloride, calcium chloride, iron (II) chloride, iron (III) chloride, aluminum chloride, magnesium nitrate, calcium nitrate, iron (II) nitrate, iron (III) nitrate, aluminum nitrate, magnesium sulfate, iron (II) sulfate and aluminum sulfate. If necessary, those polyvalent metal salts can be used as mixtures of two or more thereof.
• the alcohols, polyhydric alcohol esters, carbonates, intramolecular esters, dibasic acid esters and dialdehydes, contained as the additive A in the treating material according to the present invention can be general compounds.
• the alcohols include methanol (CH 3 OH) and ethanol (C 2 H 5 OH).
• the polyhydric alcohol esters include ethylene glycol diacetate (C 2 H 4 (OCOCH 3 ) 2 ) and triacetylene (C 3 H 5 (OCOCH 3 ) 3 .
• Examples of the carbonates include ethylene carbonate ((CHO 2 ) 2 CO).
• Examples of the intramolecular esters include gamma-butyrolactone (C 4 H 6 O 2 ).
• dibasic acid esters examples include succinic acid dimethyl ester (CH 3 OOC(CH 2 ) 2 COOCH 3 ) and glutaric acid dimethyl ester (CH 3 OOC(CH 2 ) 3 COOCH 3 ).
• dialdehydes examples include glyoxal ((CHO) 2 ).
• compounds which dissolve in water or the water glass aqueous solution and react with the water glass aqueous solution, whereby the solid component of the water glass is polymerized can also be used.
• the alcohols, polyhydric alcohol esters, carbonates, intramolecular esters, dibasic acid esters and dialdehydes each can be used as mixtures of two or more thereof.
• the amount of the additive A added can be optionally selected, but it is preferred to select the amount that the treating material has less possibility to gel when the water glass aqueous solution and the additive A are mixed. As described before, although the gelled treating material is expected to have a certain degree of the performance for stabilizing Pb, the performance is not sufficient. This may induce undesirably problems of clogging of pipes of an injection device for the treatment, a kneader of the waste and the treating material, and the like.
• the first treating material it is possible in the first treating material to add as the additive A at least two kinds selected from the acids, alcohols, polyvalent metal salts, polyhydric alcohol esters, carbonates, intramolecular esters, dibasic acid esters, and dialdehydes to the water glass aqueous solution.
• the amount of the additive B added is 10 to 400 parts by weight per 100 parts by weight of the solid content of water glass (the content of silicic acid salt in water glass aqueous solution; i.e., total weight of M 2 O content and SiO 2 content, wherein M is cation in the water glass aqueous solution; hereinafter the same) in the water glass aqueous solution. If the amount of additive B is less than 10 parts by weight, insoluble amount or sealing amount of calcium ions is small, and the desired performance is not exhibited. On the other hand, if the amount of the additive B exceeds 400 parts by weight, the performance for preventing elution of lead may rather be decreased.
• the amount of the additive B added in the treating material of the present invention varies depending on concentration of water glass aqueous solution, compositions of water glass aqueous solution, amount of water glass aqueous solution added to waste, addition method of the additive B, Pb content in the waste, calcium compound content, elution amount of harmful heavy metals from waste when not treated, allowable elution amount of harmful heavy metals to be a target, and the like.
• the amount is determined by the blending ratio of the water glass aqueous solution and the additive B so as to have the desired performance for stabilizing harmful heavy metals and to make the cost most inexpensive.
• the additive B is preferably used in an amount of 15 to 280 parts by weight per 100 parts by weight of water glass solid content in the water glass aqueous solution, so that good performance for preventing elution of harmful heavy metals can be obtained.
• Examples of the material which reacts with calcium ions to produce calcium compounds which are insoluble or sparingly soluble in water, used as the additive B in the treating material of the present invention include tripotassium phosphate, trisodium phosphate, trilithium phosphate, triammonium phosphate, dipotassium hydrogen phosphate, disodium hydrogen phosphate, diammonium hydrogen phosphate, potassium dihydrogen phosphate, sodium dihydrogen phosphate, ammonium dihydrogen phosphate, tetrapotassium diphosphate (potassium pyrophosphate), tetrasodium diphosphate (sodium pyrophosphate), tenpapotassium triphosphate (potassium tripolyphosphate), pentasodium triphosphate (sodium tripolyphosphate), hexapotassium tetraphosphate (potassium tetrapolyphosphate), hexasodium tetraphosphate (sodium tetrapoly
• Phosphates, carbonates, sulfates, carboxylates or hydroxides of potassium, sodium or ammonium are preferred, considering industrial availability, cost, Pb stabilizing performance, and the like. Of those, it is preferred to use any of tripotassium phosphate, pentasodim triphosphate (sodium tripolyphosphate), hexasodium tetraphosphate (sodium tetrapolyphosphate), sodium hexametaphosphate, potassium carbonate, sodium carbonate, sodium hydroxide, potassium hydroxide, ammonium sulfate and potassium oxalate, from the standpoint of good Pb stabilizing performance.
• tripotassium phosphate pentasodim triphosphate (sodium tripolyphosphate), hexasodium tetraphosphate (sodium tetrapolyphosphate), sodium hexametaphosphate, potassium carbonate, sodium carbonate, sodium hydroxide, potassium hydroxide, am
• carbonates particularly potassium carbonate and sodium carbonate
• hydroxides of monovalent alkali metals particularly sodium hydroxide
• the materials which react with calcium ions of the additive B to produce calcium compounds which are insoluble or sparingly soluble in water from the standpoints of Pb elution preventing performance of the treating material and industrial availability.
• hydrogen carbonate releases hydrogen ion (H + ) at the dissolution thereof, and induces gelation reaction with water glass. Therefore, it cannot be used as a one part treating material of a mixing system with water glass. That is, in the case that hydrogen carbonate is used, it is necessary to add the same separately from water glass, and it is very inconvenient practically that, for example, two sets of a tank for waste-treating material, a pump for conveying the treating material, a control system, and the like are required. Contrary to this, by using carbonates, particularly potassium carbonate or sodium carbonate, carbonic acid ions can be supplied without gelling water glass.
• Lithium carbonate can be exemplified as the carbonates having the above action.
• lithium carbonate has low solubility, and unless it has sufficiently low concentration when blending with the treating material, precipitates are formed, lacking in practical convenience.
• hydroxides of monovalent alkali metals exhibit the same effect if those are compounds which produce hydroxide ions by dissolution.
• examples of the hydroxides of monovalent alkali metals having the action as described above include sodium hydroxide, potassium hydroxide and lithium hydroxide.
• hydroxides of polyvalent (divalent or more) metal salts it acts as a gelling agent, and the treating material may undesirably gel during the storage thereof.
• the blending ratio of the water glass and potassium carbonate is preferably that a ratio of water glass solid content : potassium carbonate is in the range of 90 : 10 to 40 : 60. If the amount of potassium carbonate is less than the above range, supply of calcium ions is not sufficient, and on the other hand, if the amount exceeds the above range, the amount of water glass component is relatively decreased, and it cannot sufficiently exhibit the effect.
• the reason that the preferred blending ratio is not specified is that the optimum blending ratio varies depending on the kinds of waste to be applied, mainly calcium content. The desired effect can be exhibited to an average waste in the above-described range of the blending ratio.
• a blend of water glass and potassium carbonate is used as the treating material
• a large amount of the treating material is required if its solid content concentration is low. Therefore, a storage tank of a large size is necessary, which is disadvantageous on practical use.
• water glass used in preparing the treating material is directly used without diluting a crude liquid of aqueous solution which is industrially available.
• an aqueous solution of potassium carbonate having higher concentration is prepared, and water glass and potassium carbonate are mixed for use.
• the concentration of the potassium carbonate aqueous solution is preferably 40% or more.
• the blending ratio of the water glass and sodium carbonate is preferably such that a ratio of water glass solid content : sodium carbonate is in the range of 90 : 10 to 40 : 60, and more preferably such that the ratio of water glass content and sodium carbonate is in the range of 60 : 40 to 50 : 50 per 100 parts by weight of the water glass solid content. If the blending amount of sodium carbonate is less than the above range, capture of calcium is not sufficient, and on the other hand, if it exceeds the above range, the water glass content is relatively small, and it cannot sufficiently exhibit the effect.
• the reason that the preferred blending ratio is not specified is that the optimum blending ratio varies depending on the kinds of waste to be applied, mainly calcium content. However, from the fact that the treating material having the above-described range exhibits the desired effect to many average waste, it can be said that the above-described range is most preferably.
• sodium carbonate is dissolved in heated water of 40°C or more, and in this case, the solid content concentration is about 32% by weight.
• heated water must be provided in dissolution of sodium carbonate.
• the solubility of sodium carbonate at normal temperature (15°C) is about 15% by weight. Since dissolution of sodium carbonate involves heat generation, when dissolving in water at normal temperature, about 20% by weight of sodium carbonate is substantially dissolved.
• concentration and preparation method of the mixed aqueous solution must be determined, considering the disadvantage of providing heated water and the advantage of making the concentration of the mixed solution high. In any case, it is preferred that the concentration of sodium carbonate is set to 20% by weight or more. It is also possible to use a mixed liquid in a suspended state that the entire amount of sodium carbonate added to water glass does not dissolve.
• a hydroxide is dissolved in heated water.
• concentration of the hydroxide aqueous solution is set to 20% by weight or more.
• a method of using a blend in a suspended state that the entire amount of the hydroxide added to the water glass aqueous solution is not dissolved is also within the scope of the present invention.
• a mixed aqueous solution of the water glass aqueous solution and carbonates, or hydroxides of monovalent alkali metals of the present invention may precipitate salts of the structural components depending on temperature and solid content concentration.
• a mixed aqueous solution is heated at a constant temperature from the time of preparation according to temperature of suroundings and concentration of the solution, or when salts are precipitated without maintaining at a constant temperature, the mixed aqueous solution is used after re-dissolving part or the whole of salts.
• the temperature for maintaining at a constant temperature or heating temperature is preferably 30 to 70°C.
• the temperature is less than 30°C, it is difficult to completely prevent precipitation of salts of a blend in high concentration, and also it requires much time to re-dissolve salts precipitated.
• the temperature exceeds 70°C, there arisessuch a problem that a gel which is assumed to be a reaction product of air and the water glass is formed.
• potassium hydroxide since solubility of potassium hydroxide is high, it is sufficient only to heat to a temperature of about 5 to 30°C.
• the ion sealing agent which seals calcium ions, as the additive B means a material which is generally known to seal metal ions by bonding with metal ions.
• the ion sealing agent include potassium 1-hydroxyethane-1,1-diphosphonate, sodium 1- hydroxyethane-1,1-diphosphonate, potassium aminotrimethylene phosphonate, ethylene diamine tetraacetic acid, potassium ethylene diamine tetraacetate, sodium ethylene diamine tetraacetate, lithium ethylene diamine tetraacetate, nitrilotriacetic acid, potassium nitrilotriacetate, sodium nitrilotriacetate, chromotropic acid, sodium chromotropate, potassium chromotropate, dimethyldithiocarbamic acid, sodium dimethyldithiocarbamate, potassium dimethyldithiocarbamate, diethyldithiocarbamic acid, sodium diethyldithiocarbamate, potassium dieth
• tetrapotassium diphosphate (potassium pyrophosphate), tetrasodium diphosphate (sodium pyrophosphate), pentapotassium triphosphate (potassium tripolyphosphate), pentasodium triphosphate (sodium tripolyphophate), hexapotassium tetraphosphate (potassium tetrapolyphosphate), hexasodium tetraphosphate (sodium tetrapolyphosphate), potassium trimetaphosphate, sodium trimetaphosphate, potassium hexametaphosphate, sodium hexametaphosphate, and the like which are exemplified as the materials which produce calcium compounds which are insoluble or sparingly soluble in water, by reacting with calcium ions, and bond to calcium ions to form calcium comlex ions.
• those compounds can be exemplified as the examples of the ion sealing agent which seals calcium ions.
• phosphonates of sodium or organic chelating agents having carboxyl group (-COOX, wherein X represents hydrogen, potassium or sodium) or dithiocarbamic acid group (>NCSSY, wherein Y represents hydrogen, potassium or sodium) are preferably used considering the sealing ability to metal ions, particularly calcium ion, and potassium ethylene diamine tetraacetate, sodium ethylene diamine tetraacetate, potassium 1-hydroxyethane-1,1-diphosphonate, sodium 1-hydroxyethane-1,1-diphosphonate, sodium dimethyldithiocarbamate, potassium diethyldithiocarbamate and sodium dibutyldithiocarbamate are more preferably used considering industrial availability, cost, Pb stabilizing performance and the like.
• the additive A In the waste-treating material of the present invention, if the additive A is blended, it is required that solid component of the water glass aqueous solution is polymerized by the action of the additive A. However, if the polymerization reaction proceeds excessively, gel of water glass precipitates, i.e., solidifying with only the treating material, and as a result, it is impossible to seal harmful metals in waste. Therefore, care should sufficiently be made to storage conditions (storage form, storage place, storage time, etc.) of the treating material, and the kind and amount of the additive A added, and it is necessary to set the optimum value to ones appropriately selected.
• solid component in the water glass aqueous solution is polymerized by the action of acids, alcohols, polyvalent metal salts, polyhydric alcohol esters, carbonates, intramolecular esters, dibasic acid esters, dialdehydes and the like added as the additive A.
• this polymerization reaction proceeds excessively, gel of water glass precipitates, i.e., solidifying with only the treating material, so that it is impossible to seal harmful metals and the like in the waste.
• the treating material comprising the water glass aqueous solution and the additive A or the additive B as the main structural components in the state that an industrial problem does not arise
• at least one selected from gluconates, tartarates, benzoates, ligninsulphonates, polysaccharides, and bases comprising monovalent cation and hydroxide ion is added as a one part stabilizing agent as an additive E.
• the mechanism that the additive E stabilizes the treating material comprising the water glass aqueous solution and the additive A or the additive B as the main structural components, as a liquid is not clear, but it is assumed that such is due to an action of chelating the additive A or the additive B present in excess to conceal, or an action of controlling balance of electric charges in the treating material and pH thereof.
• stabilizing agents vary depending on properties of the stabilizing agent added, desired stabilization of the treating material, and the like, but basically it is preferred that after the reaction between the water glass aqueous solution and acids, alcohols, polyvalent metal salts, polyhydric alcohol esters, carbonates, intramolecular esters, dibasic acid esters, dialdehydes, and the like sufficiently proceeds and polymerization of solid component in the water glass aqueous solution is completed, the treating material is stored by adding a stabilizing agent thereto.
• the amount of the stabilizing agent added is practically a minimum amount necessary for attaining the desired one part stability of the treating material.
• the amount of a stabilizing agent added is about 20 parts by weight or less per 100 parts by weight of the solid component (the sum of amount of M 2 O and amount of SiO 2 ) of the water glass aqueous solution. If the stabilizing agent is added in an amount exceeding the above amount, progress of gelation of the treating material is promoted, and stability of the treating material may be undesirably decreased.
• the base comprising the monovalent cation and hydroxide ion is sodium hydroxide (NaOH), potassium hydroxide (KOH) and aqueous ammonia (NH 4 OH), considering industrial availability, cost, the performance for stabilizing the treating material in one part, and the like.
• Method of adding the treating material to the waste in the treating method of kneading the treating material comprising the water glass aqueous solution and the additive A or the additive B as the main structural components with the waste according to the present invention, and aging the mixture are, for example:
• Either of the above method (2) of mixing the water glass aqueous solution and the second component or the third component immediately before adding to the waste, and immediately adding the resulting mixture to the waste or the above method (3) of adding the water glass aqueous solution to the waste, if necessary followed by kneading, adding the additive A or the additive B thereto, kneading and aging can be selected as the method for adding the treating material to the waste.
• the above method (2) is effective in the case that a gel is not instantaneceously formed when the water glass aqueous solution and the second component are reacted, or in the case that polyvalent metal salts of the additive A are instantaneously reacted with the additive B, so that polyvalent metal compounds which are insoluble or sparingly soluble in water are not formed, or polyvalent metal ions are not sealed.
• the method (2) is effective to the treating material that although it is impossible to stably store the treating material as one part, polymerization reaction between the water glass aqueous solution and the second component proceeds until adding to the waste after mixing the treating material to form a one part, and the treating material does not gel until adding to the waste.
• the above method (3) is effective in the case that a gel is instantaneously formed when the water glass aqueous solution and the additive A are mixed or in the case that polyvalent metal salts of the additive A are instantaneously reacted with the additive B to produce polyvalent metal compounds which are insoluble or sparingly soluble in water or polyvalent metal ions are sealed.
• it is conditions for sufficiently exhibiting harmful metal stabilizing performance of the treating material that harmful metal in the waste do not elute until the water glass aqueous solution is added to the waste, if necessary, followed by kneading, and the additive A and the additive B are then added thereto, and all the water glass aqueous solution does not completely react with calcium compounds in the waste.
• the water glass aqueous solution added to the waste must be instantaneously reacted with the additive A which are added thereafter to produce a polymer of the water glass solid component, and then must be reacted with calcium compounds and the like in the waste.
• any one of the above methods (1) to (3) for treating waste it is required that a device for introducing the treating material, treating conditions and the like are appropriately set according to the properties of the treating material. Further, contrary to the above methods (1) to (3), if a method is employed that the water glass aqueous solution, the additive A and the additive B are separately stored and the additive A and the additive B are added to the waste prior to adding the water glass aqueous solution, elution of harmful metals from the waste occurs before the water glass aqueous solution stabilizes harmful metals. Therefore, this method is not preferable.
• the second waste-treating material of the present invention comprises the water glass aqueous solution having added thereto a coagulating sedimentator in an amount of 1 to 40 parts by weight per 100 parts by weight of the water glass solid component in the water glass aqueous solution. If the amount of the coagulating sedimentator added is less than 1 part by weight, the synergistic effect by co-use with the water glass is not almost recognized, and on the other hand if the amount of the coagulating sedimentator added exceeds 40 parts by weight, water glass may gel, whereby it will be difficult to use the treating material. In this treating material, although the coagulating sedimentator may not always be completely dissolved in the water glass aqueous solution.
• the treating material is uniformly added, and from this point, it is advantageous that the coagulating sedimentator is completely dissolved in the water glass aqueous solution.
• water may additionally be added to the treating material or the coagulating sedimentator may previously be dissolved in water and the resulting solution is then mixed with water glass to prepare a treating material.
• Examples of the coagulating sedimentator used in the treating material include polyalumiun chloride, sulfuric acid band, polyacrylamide, sodium polyacrylate, carbamate, polymethacrylic acid ester, polyvinyl alcohol, methyl cellulose, hydroxypropylmethyl cellulose, hydroxyethylmethyl cellulose and carboxymethyl cellulose.
• Polyalminum chloride, carbamate, polyacrylamide, sodium polyacrylate, polyvinyl alcohol, methyl cellulose and carboxymethyl cellulose are preferred considering Pb stabilizing performance and the like. Those compounds may be used alone or as mixtures of two or more thereof as the coagulating sedimentator.
• the treating material aqueous solution wherein the solid component is precipitated becomes a form unusable as a liquid, and disadvantageous problems induce that pipings of a device for introducing the treating material aqueous solution, a kneader for the waste and the treating material aqueous solution, and the like may possibly clog, which is undesirable.
• the treating material aqueous solution in which solid component is precipitated can be expected to have the Pb stabilizing performance in a certain degree, but it is not sufficient.
• the amount of the monovalent metal salts added is preferably such that the amount of monovalent metal ions of the monovalent metal salts is 100 parts by mol or less per 100 parts by mol of cations in the water glass aqueous solution.
• the amount of the monovalent metal salts added is such that the amount of monovalent metal ions of the monovalent metal salts is 5 parts by mol or more per 100 parts by mol of cations in the water glass aqueous solution.
• the amount of ammonium salts as the additive D is preferably such that the amount of ammonium ions of the ammonium salts is more than 5 to 100 parts by mol per 100 parts by mol of cations in the water glass aqueous solution.
• the monovalent metal salts may be any salts so long as it ionizes in water or the water glass aqueous solution to release monovalent metal ions, and it does not produce calcium compounds which are insoluble or sparingly soluble in water by reacting with calcium ions.
• Examples of the monovalent metal salts include chlorides or nitrates of sodium or potassium. Of those, sodium chloride and potassium chloride are preferred considering industrial availability, Pb stabilizing performance, and the like. It is also within the scope of the present invention that at least two of different kinds of monovalent metal salts are used together if necessary.
• the ammonium salts may be any salt so long as it ionizes in water of the water glass aqueous solution to release ammonium ion, and it does not produce calcium compounds which are insoluble or sparingly soluble in water by reacting with calcium ions.
• ammonium chloride is preferably used considering industrial availability, cost, Pb stabilizing performance, and the like. If necessary, at least two different kinds of ammonium salts can be used together.
• the amounts of those additives A, B, C and D vary depending on concentration of the water glass aqueous solution, compositions of the water glass aqueous solution, amount of the water glass aqueous solution added to the waste, method for adding the additive A, Pb content in the waste, calcium compound content, elution amount of harmful metals from the waste in the case of non-treatment, and intended elution allowable amount of harmful metals, such as a rule-regulated value in a filled-in land and the like. Practically, those amounts are determined by the blending ratio of the water glass aqueous solution and the additives A, B, C and D such that the treating material has a predetermined performance for stabilizing harmful metals, and is most inexpensive. If desired and necessary, the water glass aqueous solution may be combined with the additives A, B, C and D in any optional blending ratio.
• the aging temperature in this case is preferably about 40 to 100°C.
• the function of this aging is not entirely understood, but it is considered that by aging a blend of the treating material and the waste by heating to the above temperature range, reaction which proceeds during aging is accelerated. It is also assumed that reaction product produced in aging becomes more stable state, and the effect for more strongly preventing elution of harmful metals contained is improved.
• the aging temperature varies depending on Pb content in the waste, calcium compound content, elution amount of harmful metals from the waste in the case of non-treatment, and intended elution allowable amount, such as rule-regulated value applied to a place where treated materials are disposed, and the like.
• the ability for stabilizing harmful metals and the like are improved by setting the aging temperature to higher temperature.
• the temperature in aging a blend of the waste and the treating material is preferably 40 to 100°C.
• the aging temperature is more preferably 80°or less. Aging under heating up to such a temperature is effective in the case that a site for aging the treated material after treating the treating material is not sufficiently secured. In other words, it is possible to shorten the aging time by aging a blend obtained by kneading the waste and the treating material at a predetermined temperature, and this enables the treated material to rapidly discard.
• a solidification strength of a blend of the waste and the treating material increase as increasing the aging time. Therefore, where aging is not conducted for sufficient time, the blend lacks in solidification strength.
• a treated material disintegrates during transportation of the same from aging pit to a cart, filled-in land, and the like, or in the filled-in land, dusts containing harmful metals scatter and there is the possibility to contaminate surrounding environment.
• the aging time is less than 6 hours, it is insufficient to proceed polymerization reaction during the period of aging, and the treating material may not exhibit the desired performance for stabilizing harmful metals. From the reasons above, the blend of the waste and the treating material is preferably aged for 6 hours or more.
• a site for treating waste is located near waste incineration facilities.
• heat generated in waste incineration is recovered as steam.
• generation of electric power is conducted utilizing the steam. It is industrially useful in the method for treating waste according to the present invention to utilize steam recovered from a heat exchanger of the incineration site as heat source in aging a blend obtained by kneading the waste and the treating material, and to utilize electric power obtained by utilizing the steam, leading to an effective use of energy from an industrial standpoint.
• the amount of the water glass aqueous solution added to the waste is not generally determined because the Pb stabilizing performance of the treating material varies depending on the amounts of the additives A, B, C and D added. However, practically it is a factor for determining the amount of the water glass aqueous solution added from the standpoint of cost that the intended elution amount or less is achieved by addition of the water glass aqueous solution in the smallest amount, although varying depending on Pb content in the waste, calcium compound content, elution amount of harmful metals from the waste in the case of non-treatment, and intended elution allowable amount, such as rule-regulated value.
• the amount of the water glass aqueous solution is preferably 20 parts by weight or less in terms of the solid component therein per 100 parts by weight pf the waste.
• the treating material may previously be diluted with water, or the treating material and the waste may be mixed or kneaded and water may then be added to the resulting mixture, followed by kneading.
• the sum of water in the treating material and water added is preferably 25 parts by weight per 100 parts by weight of the waste where the waste is relatively dried material. If the amount of water is too large, problems may induce such that handling property of the waste after kneading is poor, and the treating material does not exhibit the desired effect. Therefore, care should be taken in this regard.
• the waste-treating material of the present invention can also stabilize harmful metals including Pb contained in industrial waste such as collected dust generated in electric furnace or zinc plating step, which does not contain calcium compounds such as calcium hydroxide, calcium oxide or calcium chloride, which may be capable of forming a gelling agent of the water glass aqueous solution, or which does not contain other polyvalent metal salts.
• harmful metals including Pb contained in industrial waste such as collected dust generated in electric furnace or zinc plating step, which does not contain calcium compounds such as calcium hydroxide, calcium oxide or calcium chloride, which may be capable of forming a gelling agent of the water glass aqueous solution, or which does not contain other polyvalent metal salts.
• calcium hydroxide, calcium oxide, calcium chloride and the like which are capable of forming a gelling agent of the water glass aqueous solution, or other polyvalent metal salts are previously blended with the waste, so that it is possible to exhibit the harmful metal stabilizing performance of the treating material and the method for treating waste, according to the present invention by the same action mechanism as in the treatment of the waste containing calcium compounds such as calcium hydroxide, calcium oxide or calcium chloride.
• the treating material and the method for treating waste, according to the present invention makes it possible to conduct stabilization treatment of harmful metals in the waste containing calcium compounds such as calcium hydroxide, calcium oxide or calcium chloride, in particular Pb in waste incineration fly ash.
• Analytical result of components of bag filter collected fly ash (I) formed in municipal refuse incineration facility is shown in Table 1 below. TABLE 1 Analytical result of components of bag filter collected fly ash (I) formed in municipal refuse incineration facility (% by weight) Component Analytical result Ca(OH) 2 12.5 CaCl 2 ⁇ Ca(OH) 2 ⁇ H 2 O 24.6 Pb 0.65
• This fly ash (I) containing calcium compound was subjected to an elution test defined by Notification No. 13 of the Environment Agency (Japan) (hereinafter referred to as "elution test” for simplicity) in a non-treated state.
• hydrochloric acid 36% HCl
• a water glass aqueous solution prepared by adding 26.0 g of water to the same sodium silicate solution (I) as used in Comparative Example 2 above.
• the resulting solution (hydrogen ion of hydrochloric acid was 75 parts by mol per 100 parts by mol of alkali metal of the water glass aqueous solution) formed gel instantaneously.
• a calcium chloride aqueous solution (0.86 g of CaCl 2 was dissolved in 26.0 g of water) was added to 6.5 g (solid content: 2.5 g) of the sodium silicate solution (I) as used in Comparative Example 2 above (hereinafter referred to a "sodium silicate solution (I)" for simplicity).
• the resulting solution (the product of the part by mol of calcium ion and the number of valency was 75 parts by mol per 100 parts by mol of cations of the water glass aqueous solution) formed gel instantaneously.
• it was impossible to add such a solution as a treating material to 50 g of the fly ash (I) and to knead those.
• the solidified product was pulverized, and classified with a sieve having an opening of 5 mm. 30 g of particles was dispensed from particles which passed through the sieve, and then subjected to the elution test.
• the resulting solution (the product of the part by mol of calcium ions and the number of valency was 50 parts by mol per 100 parts by mol of cations of the water glass aqueous solution) was allowed to stand for 5 minutes, and then added as a treating material to 50 g of the fly ash (I) above.
• the resulting kneaded product (the solid content of the water glass aqueous solution was 5 parts by weight per 100 parts by weight of the ash) was aged, solidified, pulverized, and classified with a sieve in the same manner as in Example 1, and then subjected the elution test.
• the elution test was conducted in the same manner as in Example 3 except that the following solution was used in place of the calcium chloride aqueous solution as the additive A.
• the elution test was conducted in the same manner as in Example 1 except that the following compound was used in place of hydrochloric acid as the additive A.
• the elution test was conducted in the same manner as in Example 3 except that the following solution was used in place of the calcium chloride aqueous solution as the additive A.
• 0.52 g of sulfuric acid (97%H 2 SO 4 ) as the additive A was added to a water glass aqueous solution prepared by adding 26.0 g of water to the sodium silicate aqueous solution (I).
• 0.03 g of sodium gluconate (1 part by weight per 100 parts by weight of the water glass solid content) as an additive E was added to the resulting mixture (hydrogen ion of sulfuric acid was 50 parts by mol per 100 parts by mol of cations of the water glass aqueous solution) to prepare a treating material.
• the treating material was added to 50 g of the fly ash (I) above, and kneaded.
• the resulting kneaded product (the solid content of the water glass aqueous solution was 5 parts by weight per 100 parts by weight of the ash) was aged, solidified, pulverized and classified with a sieve in the same manner as in Example 1, and then subjected to the elution test. Further, gelation of the above treating material was visually observed, and a one part stability was examined.
• Example 30 The elution test was conducted in the same manner as in Example 30 except that the following compound was used in place of sodium gluconate as the additive E. Further, gelation of each treating material was visually observed, and the one part stability was examined.
• Hydrochloric acid (2.10 g of 36% HCl was dissolved in 26.0 g of water) as the additive A was added to 6.5 g of the sodium silicate aqueous solution (I) (solid content: 2.5 g) to prepare a treating material.
• the treating material was instantaneously added to 50 g of the fly ash (I) above, and kneaded.
• the resulting kneaded product (the solid content of the water glass aqueous solution was 5 parts by weight per 100 parts by weight of the ash) was subjected to the elution test in the same manner as in Example 1.
• the solidified product was pulverized, and classified with a sieve having an opening of 5 mm. 30 g of particles was dispensed from particles which passed through the sieve, and then subjected to the elution test.
• the elution test was conducted in the same manner as in Example 55 except that the aging temperature was 60°C and the aging time was 6 hours.
• the elution test was conducted in the same manner as in Example 55 except that the aging temperature was 60°C and the aging time was 2 hours.
• the elution test was conducted in the same manner as in Example 1 except that a treating material obtained by adding 0.97 g of phenol (C 6 H 5 OH) in place of hydrochloric acid was used (hydrogen ion of phenol was 50 parts by mol per 100 parts by mol of cations of the water glass aqueous solution).
• the elution test was conducted in the same manner as in Example 12 except that a treating material obtained by adding 0.52 g of sulfuric acid (97%H 2 SO 4 ) to an aqueous solution obtained by adding 26.0 g of water to 6.3 g (solid content: 2.5 g) of a potassium silicate aqueous solution manufactured by Nippon Chemical Industrial Co., Ltd. (trade name: A POTASSIUM SILICATE, solid content: 40.0%) was used.
• Example 1 The elution test results obtained in Examples 1 to 60 above are shown in Table 3 below. Further, the one part stability of each treating material is shown in Table 4 below. TABLE 3 Elution Amount of Pb (ppm) Example 1 5.8 Example 2 41 Example 3 11 Example 4 38 Example 5 35 Example 6 42 Example 7 44 Example 8 39 Example 9 4.7 Example 10 16 Example 11 30 Example 12 7.3 Example 13 3.0 Example 14 5.8 Example 15 43 Example 16 45 Example 17 36 Example 18 13 Example 19 6.3 Example 20 4.1 Example 21 2.1 Example 22 23 Example 23 21 Example 24 15 Example 25 12 Example 26 8.1 Example 27 24 Example 28 19 Example 29 9.5 Example 30 4.1 Example 31 7.6 Example 32 7.4 Example 33 7.1 Example 34 7.7 Example 35 7.3 Example 36 5.9 Example 37 6.0 Example 38 6.3 Example 39 5.4 Example 40 36 Example 41 8.0 Example 42 29 Example 43 26 Example 44 35 Example 45 39 Example 46 31 Example 47 6.0 Example 48 39 Example 49 13 Example 50 40 Example 51 34 Example 52 39 Example 53 44 Example 54 37 Example 55 2.8 Example 56 1.8 Example 57 30 Example 58 48
• the amount of the acid added in the treating material of the present invention is preferably that hydrogen ion of the acid is 50 parts by mol or less per 100 parts by mol of cations in the water glass aqueous solution.
• the amount of the polyvalent metal salts added as the additive A in the treating material of the present invention is preferably that the product of the part by mol of polyvalent metal ions of the polyvalent metal salts and the number of valency is 50 parts by mol or less per 100 parts by mol of cations in the water glass aqueous solution.
• the waste-treating material comprises the water glass aqueous solution and the polyvalent metal salts as the additive A as the main structural components
• the polyvalent metal salts used are any of chlorides, nitrates, sulfates, carbonates or phosphates of magnesium, calcium, strontium, barium, iron, aluminum or zinc, and preferably any of magnesium chloride, calcium chloride, iron (II) chloride, iron (III) chloride, aluminum chloride, magnesium nitrate, calcium nitrate, iron (II) nitrate, iron (III) nitrate, aluminum nitrate, magnesium sulfate, iron (II) sulfate, and aluminum sulfate
• the treating material has excellent Pb stabilizing performance as compared with the use of only the water glass aqueous solution.
• Example 12 From the comparison between Example 12 and Example 59, it is apparent that the water glass aqueous solution comprising sodium silicate (Na 2 O ⁇ nSiO 2 ) as the main structural component has excellent Pb stabilizing performance as compared with the case of using potassium silicate (K 2 O ⁇ nSiO 2 ) as the main structural component.
• sodium silicate Na 2 O ⁇ nSiO 2
• K 2 O ⁇ nSiO 2 potassium silicate
• Example 12 From the comparison between Example 12 and Examples 30 to 38, it is apparent that the treating material comprising the water glass aqueous solution and the additive A as the main structural components, and the treating material comprising the above treating material and having added thereto any of gluconats, tartarates, benzoates, ligninsulfonates, polysaccharides, and bases comprising monovalent cations and hydroxide ions, as the additive E do not have substantially clear difference when comparing the Pb stabilizing performance, but the one part stability of the treating material is apparently improved; and from Examples 36 to 38, if sodium hydroxide, potassium hydroxide or aqueous ammonia is preferably used as the additive E, the one part stability is further improved as compared with other one part stabilizing agents, and such a treating material has excellent Pb stabilizing performance as compared with the treating material having other stabilizing agents added thereto.
• Example 55 From the comparison between Example 55 and Example 12, it is apparent that the Pb stabilizing performance is improved by conducting the aging at 40°C or more.
• the elution amount of Pb can be decreased as compared with the case of using only the water glass aqueous solution.
• the present inventors recognize that by appropriately setting the amount of the treating material added, the aging time after kneading the waste and the treating material, the temperature during aging, and the like, the treating material and the treatment method as described above are capable of decreasing the elution amount of PB to 0.3 ppm or less which is the standard value for filling-up.
• the fly ash (II) containing the calcium compound was subjected to the elution test as described before without treatment.
• the elution test was conducted in the same manner as in Comparative Example 9 except that the amount of the sodium silicate aqueous solution (I) used was changed to 9.1 g (solid content: 3.5 g) (the solid content of the water glass aqueous solution was 7 parts by weight per 100 parts by weight of the ash).
• the elution test was conducted in the same manner as in Comparative Example 9 except that the amount of the sodium silicate aqueous solution (I) used was changed to 13 g (solid content: 5.0 g) (the solid content of the water glass aqueous solution was 10 parts by weight per 100 parts by weight of the ash).
• a treating material was prepared in the same manner as in Comparative Example 12 except for using 13 g (solid content: 5.0 g) of the sodium silicate solution (I) and 1.0 of sulfuric acid. Immediately after adding the sulfuric acid aqueous solution to the water glass aqueous solution, the treating material was solidified, and it was impossible to add the treating material to the fly ash (II) and knead those.
• aqueous solution prepared by adding 0.52 g of sulfuric acid to 26.0 g of water (hydrogen ion of sulfuric acid was 50 parts by mol per 100 parts by mol of cations in the water glass aqueous solution) was added to 6.5 g (solid content: 2.5 g) of the sodium silicate aqueous solution (I) to prepare a treating material.
• the treating material was instantaneously added to 50 g of the fly ash (II), and kneaded.
• the resulting kneaded product (the solid content of the water glass aqueous solution was 5 parts by weight per 100 parts by weight of the ash) was aged at 20°C for 24 hours to solidify.
• the solidified product was pulverized, and classified with a sieve having an opening of 5 mm. 30 g of particles was dispensed from the particles which passed through the sieve, and was subjected to the elution test.
• the elution test was conducted in the same manner as in Example 61 except the after 5 minutes from the preparation of the treating material, the treating material was added to the fly ash (II).
• the elution test was conducted in the same manner as in Example 61 except for using 9.1 g (solid content:3.5 g) of the sodium silicate aqueous solution (I) and 0.73 g of sulfuric acid.
• An aqueous solution prepared by adding 26.0 g of water to 13.0 g (solid content: 5.0 g) of the sodium silicate aqueous solution (I) was used as a treating material.
• the treating material was added to 50 g of the fly ash (II), and kneaded.
• 1.0 g of sulfuric acid was further added to the kneaded mixture, and the kneaded.
• the resulting kneaded product was aged at 20°C for 24 hours to solidify. After completion of the solidification, the solidified product was pulverized, and classified with a sieve having an opening of 5 mm. 30 g of particles was dispensed from the particles which passed through the sieve, and was subjected to the elution test.
• the elution test was conducted in the same manner as in Comparative Example 2 except that the amount of the sodium silicate solution (I) used was changed to 9.1 g (solid content: 3.5 g) (the solid content of the water glass aqueous solution was 7 parts by weight per 100 parts by weight of the ash).
• the elution test was conducted in the same manner as in Comparative Example 15 except the the aging time was changed to 7 days (168 hours).
• tripotassium phosphate as the additive B was added to an aqueous solution prepared by adding 26.0 g of water to 6.5 g (solid content: 2.5 g) of the sodium silicate aqueous solution (I) to prepare a treating material (the amount of tripotassium phosphate was 40 parts by weight per 100 parts by weight of the solid content of the water glass aqueous solution).
• the treating material was added to 50 g of the above fly ash (III), and kneaded.
• the kneaded product (the solid content of the water glass aqueous solution was 5 parts by weight per 100 parts by weight of the ash) was aged at 20°C for 24 hours to solidify.
• the solidified product was pulverized, and classified with a sieve having an opening of 5 mm. 30 g of particles was dispensed from the particles which passed through the sieve, and was subjected to the elution test.
• the kneaded product (the solid content of the water glass aqueous solution was 5 parts by weight per 100 parts by weight of the ash) was aged at 20°C for 24 hours to solidify. After completion of the solidification, the solidified product was pulverized, and classified with a sieve having an opening of 5 mm. 30 g of particles was dispensed from the particles which passed through the sieve, and was subjected to the elution test. Further, gelation of the above treating material was visually observed to examine the one part stability.
• Example 88 The elution test was conducted in the same manner as in Example 88 except that the following compound was used in place of potassium tartrate as the additive E. Further, gelation of the treating material was visually observed to examine the one part stability.
• the elution test was conducted in the same manner as in Example 75 except that the aging temperature was 120°C and the aging time was 48 hours. However, in this case, the solidified product was in a dry state, that is, in the state that it was liable to scatter.
• the solidified product was pulverized, and classified with a sieve having an opening of 5 mm. 30 g of particles was dispensed from the particles which passed through the sieve, and was subjected to the elution test.
• aqueous solution prepared by adding 26.0 g of water to 6.5 g (solid content: 2.5 g) of the sodium silicate aqueous solution (I) was added to 50 g of the above fly ash (III), and then kneaded (the solid content of the water glass aqueous solution was 5 parts by weight per 100 parts by weight of the ash), and 7.0 g of ammonium sulfate (280 parts by weight per 100 parts by weight of the solid content of the water glass aqueous solution) was additionally added thereto, and then kneaded.
• the kneaded product was aged at 20°C for 24 hours to solidify.
• the solidified product was pulverized, and classified with a sieve having an opening of 5 mm. 30 g of particles was dispensed from the particles which passed through the sieve, and was subjected to the elution test.
• the elution test was conducted in the same manner as in Example 94 except that the additive E was changed to 0.50 g of potassium benzoate (20 parts by weight per 100 parts by weight of the solid content of the water glass aqueous solution). Further, gelation of the treating material was visually observed to examine the one part stability.
• the elution test was conducted in the same manner as in Example 94 except that the additive E was changed to 0.65 g of potassium benzoate (26 parts by weight per 100 parts by weight of the solid content of the water glass aqueous solution). Further, gelation of the treating material was visually observed to examine the one part stability.
• Example 65 0.62
• Example 66 1.5
• Example 67 0.87 Example 68 0.28
• Example 69 1.3
• Example 70 0.69
• Example 71 0.57
• Example 72 0.55
• Example 73 0.60
• Example 74 0.77
• Example 75 0.69
• Example 76 0.75
• Example 78 0.70
• Example 79 0.70
• Example 80 0.72
• Example 82 0.80 Example 83 0.75
• Example 84 0.82 Example 85 0.75
• Example 86 0.85 Example 87 0.41
• Example 88 0.57 Example 89 0.51
• Example 90 0.72 Example 91 0.75
• Example 92 0.60
• Example 93 0.97
• Example 94 0.65
• Example 95 0.50
• Example 96 0.53 Example 97 0.55
• Example 98 0.53 Example 99 0.55
• Example 100 0.55
• Example 101 0.55
• Example 102 0.55
• Example 103 0.44
• Example 104 0.40 Example 105 0.87
• the amount of the additive B is preferably 10 to 400 parts by weight per 100 parts by weight of the solid content of the water glass aqueous solution in view of the Pb stabilizing performance.
• the treating material water glass aqueous solution comprising sodium silicate (Na 2 O ⁇ nSiO 2 ) as the main structural component has excellent Pb stabilizing performance as compared with potassium silicate (K 2 O ⁇ nSiO 2 ), and is more preferable embodiment as the treating material.
• a crude solution of the sodium silicate aqueous solution (I) and a sodium carbonate aqueous solution (solid content: 30.8%) at 70°C were mixed in the blending ratio as shown in Table 10 to prepare a treating material.
• 20 g of water was added to each of the treating material, and kneaded such that the sum (solid content) of the solid content of the water glass aqueous solution and the solid content of sodium carbonate contained in the treating material aqueous solution was 0.5 g per 50 g of the fly ash (V).
• the kneaded product was aged at 20°C for 24 hours. After aging, the product was pulverized and classified with a sieve having an opening of 5 mm.
• the treating material of Example 117 was evaluated for the storage stability at 6 to 70°C.
• the evaluation was conducted using two methods of evaluation method 1 and evaluation method 2.
• the evaluation method 1 was that 150 g of the treating material was allowed to stand at each temperature for 40 days, precipitation of salt, and formation of gel were visually observed, and the results were recorded.
• the evaluation method 2 was that the treating material was allowed to stand one day at each temperature, then 0.3 g of sodium carbonate solid powder was added to 150 g of the treating material, the resulting mixture was allowed to stand for 6 hours, formation of gel was visually observed, and the results were recorded.
• Table 13 The results obtained are shown in Table 13 below.
• the treating material comprising a mixed solution of the water glass aqueous solution and sodium carbonate is extremely effective for preventing the Pb elution in the waste.
• a blend wherein the weight ratio of the water glass solid content and the sodium carbonate solid content in the mixed solution is 90 : 10 to 40 : 60 shows excellent Pb elution preventing performance.
• the optimum mixing ratio varies depending on types of the waste, but it is understood that on the average, the mixed solution wherein the weight ratio of the water glass solid content and the sodium carbonate solid content is 60 : 40 to 50 : 50 is most preferred.
• Example 121 it is shown in Example 121 to be necessary to maintain a temperature of at least 25°C, but it is understood that it is necessary to maintain a temperature of 30°C to less than 70°C, considering reliability from the industrial standpoint.
• a crude solution of the sodium silicate aqueous solution (I) and a sodium hydroxide aqueous solution (solid content: 45.5 %) at 70°C were mixed in the blending ratio as shown in Table 14 to prepare a treating material.
• 23 g of water was added to each of the treating material, and kneaded such that the sum (solid content) of the solid content of the water glass aqueous solution and the solid content of sodium hydroxide contained in the treating material aqueous solution was 5 g per 50 g of the fly ash (IV).
• the kneaded product (the solid content of the treating material was 10 parts by weight per 100 parts by weight of the ash) was aged at 20°C for 24 hours.
• Example 14 Elution Test Result Type of treating material Treating material (parts by weight) Pb elution amount (ppm) Water glass solid content Na 2 CO 3 solid content Comparative Example 21 0 100 110 Example 122 20 80 14 Example 123 40 60 6.3 Example 124 50 50 6.2 Example 125 60 40 5.9 Example 126 70 30 6.6 Example 127 90 10 8.5 Comparative Example 22 100 0 16
• a treating material having blended therewith potassium hydroxide in an amount of 67 parts by weight per 100 parts by weight of the water glass solid content was prepared in the same manner as in Example 125 except that potassium hydroxide was used in place of sodium hydroxide, and was evaluated in the same manner as in Example 125.
• the Pb elution amount was 6.00 ppm.
• the treating material comprising a mixed aqueous solution of the water glass aqueous solution and the hydroxide as the additive B according to the present invention is extremely effective for preventing the Pb elution in the waste.
• a blend wherein the weight ratio of the water glass solid content and the hydroxide solid content is 90 : 10 to 40 : 60 shows excellent Pb preventing performance.
• the blend wherein the weight ratio of the water glass solid content and the hydride solid content is 60 : 40 is most preferred.
• a crude solution of the sodium silicate aqueous solution (I) and a potassium carbonate aqueous solution (solid content: 36.6%) at 40°C were mixed in the blending ratio as shown in Table 15 to prepare a treating material.
• 20 g of water was added to each of the treating material, and kneaded such that the sum (solid content) of the solid content of the water glass aqueous solution and the solid content of potassium carbonate contained in the treating material aqueous solution was 5.0 g per 50 g of the fly ash (V).
• the kneaded product (the solid content of the treating material was 15 parts by weight per 100 parts by weight of the ash) was aged at 20°C for 24 hours.
• Example 131 The treating material of Example 131 was evaluated for the storage stability at 0 to 30°C. The evaluation was conducted using two methods of evaluation method 1 and evaluation method 2 in the same manner as in Example 121. The results obtained are shown in Table 16 below. TABLE 16 Storage Stability of Treating Material Temperature (°C) Evaluation method 1 Evaluation method 2 0 Precipitation of salt observed Precipitation of salt increased 5 Slight precipitation of salt, and slight formation of gel No precipitation of salt, and no formation of gel 10 No precipitation of salt, and no formation of gel No precipitation of salt, and no formation of gel 20 No precipitation of salt, and no formation of gel No precipitation of salt, and no formation of gel 30 No precipitation of salt, and no formation of gel No precipitation of salt, and no formation of gel
• the treating material comprising a mixed solution of the water glass aqueous solution and potassium carbonate is extremely effective for preventing the Pb elution in the waste. Further, it is understood that a blend wherein the weight ratio of the water glass solid content and the potassium carbonate solid content in the mixed solution is 90 : 10 to 40 : 60 shows particularly excellent Pb elution preventing performance.
• aqueous solution prepared by dissolving 1.58 g of hydrochloric acid (36% HCl) (hydrogen ion (H + ) of hydrochloric acid was 75 parts by mol per 100 parts by mol of cations of the water glass aqueous solution) and 1.0 g of tripotassium phosphate (40 parts by weight per 100 parts by weight of the solid content of the water glass aqueous solution) in 26.0 g of water was added to the sodium silicate aqueous solution (I).
• Gel was instantaneously formed, and it was impossible to add the resulting solution to the fly ash (I) and knead those.
• the resulting kneaded product (the solid content of the water glass aqueous solution was 5 parts by weight per 100 parts by weight of the ash) was aged at 120°C for 6 hours to solidify.
• the solidified product was in a dry state, that is, in the state that the product was liable to scatter.
• the solidified product was classified with a sieve having an opening of 5 mm. 30 g of particles was dispensed from the particles which passed through the sieve, and the subjected to the elution test.
• aqueous solution prepared by dissolving 1.05 g of hydrochloric acid (36% HCl) (hydrogen ion (H + ) of hydrochloric acid was 50 parts by mol per 100 parts by mol of cations of the water glass aqueous solution) as the additive A and 1.0 g of tripotassium phosphate (40 parts by weight per 100 parts by weight of the solid content of the water glass aqueous solution) as the additive B in 26.0 g of water was added to 6.5 g (solid content: 2.5 g) of the sodium silicate solution.
• the resulting solution (the solid content of the water glass aqueous solution was 5 parts by weight per 100 parts by weight of the ash) was added as a treating material to 50 g of the fly ash (I), and then kneaded.
• the resulting kneaded product was aged, solidified, classified with sieve, and then subjected to the elution test in the same manner as in Comparative Example 2.
• the elution test was conducted in the same manner as in Example 135 except that 0.48 g of ethanol was added in place of hydrochloric acid.
• the elution test was conducted in the same manner as in Example 135 except that 0.97 g of phenol was added in place of hydrochloric acid.
• a tripotassium phosphate aqueous solution (1.0 g of tripotassium phosphate (40 parts by weight per 100 parts by weight of the solid content of the water glass aqueous solution) was dissolved in 6.0 g of water) as the additive B was added to the solution to prepare a treating material.
• the treating material was added to 50 g of the fly ash (I) and then kneaded.
• the resulting kneaded product (the solid content of the water glass aqueous solution was 5 parts by weight per 100 parts by weight of the ash) was aged at 20°C for 24 hours to solidify. After solidification, the solidified product was pulverized and classified with a sieve having an opening of 5 mm. 30 g of particles was dispensed from the particles which passed through the sieve, and then subjected to the elution test in the same manner as above.
• Example 131 The elution test was conducted in the same manner as in Example 131 except that the following compound was used in place of hydrochloric acid as the additive A.
• the resulting kneaded product (the solid content of the water glass aqueous solution was 5 parts by weight per 100 parts by weight of the ash) was aged at 20°C for 24 hours to solidify. After solidification, the solidified product was pulverized and classified with a sieve having an opening of 5 mm. 30 g of particles was dispensed from the particles which passed through the sieve, and then subjected to the elution test in the same manner as above. Further, gelation of the treating material was visually observed to examine the one part stability. The results obtained are shown in Table 23 below.
• the elution test was conducted in the same manner as in Example 135 except that a treating material prepared by adding 0.62 g of acetic acid in place of hydrochloric acid as the additive A was used (hydrogen ion (H + ) of acetic acid was 50 parts by mol per 100 parts by mol of cations of the water glass aqueous solution).
• the elution test was conducted in the same manner as in Example 135 except that a treating material prepared by adding 0.47 g of oxalic acid (98%(COOH) 2 ) in place of hydrochloric acid as the additive A was used (hydrogen ion (H + ) of oxalic acid was 50 parts by mol per 100 parts by mol of cations of the water glass aqueous solution).
• Example 135 to 149 The elution test results obtained in Examples 135 to 149 above are shown in Table 18 below. TABLE 18 Pb Elution Amount (ppm) Example 135 2.5 Example 136 18 Example 137 27 Example 138 5.3 Example 139 18 Example 140 13 Example 141 21 Example 142 20 Example 143 16 Example 144 2.1 Example 145 6.2 Example 146 21 Example 147 3.4 Example 148 1.7 Example 149 2.7
• aqueous solution prepared by dissolving 1.05 g of hydrochloric acid (36% HCl) (hydrogen ion (H + ) of hydrochloric acid was 50 parts by mol per 100 parts by mol of cations of the water glass aqueous solution) as the additive A and 1.0 g of tripotassium phosphate (40 parts by weight per 100 parts by weight of the solid content of the water glass aqueous solution) as the additive B in 26.0 g of water was added to 6.5 g (solid content: 2.5 g) of the sodium silicate solution.
• the resulting solution was immediately added as a treating material to 50 g of the fly ash (I), and then kneaded.
• the resulting kneaded product (the solid content of the water glass aqueous solution was 5 parts by weight per 100 parts by weight of the ash) was aged, solidified, classified with sieve, and then subjected to the elution test in the same manner as in Comparative Example 2.
• Example 150 The elution test was conducted in the same manner as in Example 150 except that the treating material was prepared using the following material in place of hydrochloric acid as the additive A.
• a zinc sulfate aqueous solution (0.83 g of zinc sulfate was dissolved in 20.0 g of water) as the additive A was added to 6.5 g (solid content: 2.5 g) of the sodium silicate solution (I), and the resulting solution (the product of the amount of zinc ion and the number of valency is 50 parts by mol per 100 parts by mol of cations of the water glass aqueous solution) was allowed to stand for 5 minutes.
• a tripotassium phosphate aqueous solution (1.0 g of tripotassium phosphate (40 parts by weight per 100 parts by weight of the solid content of the water glass aqueous solution) was dissolved in 6.0 g of water) as the additive B was added to the solution to prepare a treating material.
• the treating material was added to 50 g of the fly ash (I) and then kneaded.
• the resulting kneaded product (the solid content of the water glass aqueous solution was 5 parts by weight per 100 parts by weight of the ash) was aged at 20°C for 24 hours to solidify. After solidification, the solidified product was pulverized and classified with a sieve having an opening of 5 mm. 30 g of particles was dispensed from the particles which passed through the sieve, and then subjected to the elution test in the same manner as above.
• Example 154 The elution test was conducted in the same manner as in Example 154 except that the following solution was used in place of the zinc sulfate aqueous solution as the additive A.
• aqueous solution prepared by dissolving 0.03 g of strontium carbonate as the additive A and 1.0 g of tripotassium phosphate (40 parts by weight per 100 parts by weight of the solid content of the water glass aqueous solution) as the additive B in 26.0 g of water was added to 6.5 g (solid content: 2.5 g) of the sodium silicate solution.
• the resulting solution was added as a treating material to 50 g of the fly ash (I), and then kneaded.
• the resulting kneaded product (the solid content of the water glass aqueous solution was 5 parts by weight per 100 parts by weight of the ash) was aged at 20°C for 24 hours to solidify.
• the solidified product was pulverized and classified with a sieve having an opening of 5 mm. 30 g of particles was dispensed from the particles which passed through the sieve, and then subjected to the elution test in the same manner as above.
• the elution test was conducted in the same manner as in Example 170 except that a treating material obtained by adding 0.03 g of barium phosphate was used in place of strontium carbonate.
• Example 150 The elution test results obtained in Examples 150 to 171 above are shown in Table 19 below. TABLE 19 Pb Elution Amount (ppm) Example 150 3.2 Example 151 2.9 Example 152 8.1 Example 153 29 Example 154 4.7 Example 155 2.6 Example 156 3.9 Example 157 22 Example 158 4.9 Example 159 3.2 Example 160 2.4 Example 161 1.3 Example 162 14 Example 163 11 Example 164 8.5 Example 165 7.8 Example 166 5.0 Example 167 14 Example 168 10 Example 169 4.7 Example 170 28 Example 171 27
• Hydrochloric acid (2.10 g of 36% HCl was dissolved in 20.0 g of water) as the additive A and a tripotassium phosphate aqueous solution (1.0 g of tripotassium phosphate (40 parts by weight per 100 parts by weight of the solid content of the water glass aqueous solution) was dissolved in 6.0 g of water) as the additive B were simultaneously added to 6.5 g(solid content: 2.5 g) of the sodium silicate solution (I). The resulting solution was added as a treating material to 50 g of the fly ash (I), and then kneaded.
• a tripotassium phosphate aqueous solution 1.0 g of tripotassium phosphate (40 parts by weight per 100 parts by weight of the solid content of the water glass aqueous solution) was dissolved in 6.0 g of water
• the additive B were simultaneously added to 6.5 g(solid content: 2.5 g) of the sodium silicate solution (I).
• the resulting kneaded product (the solid content of the water glass aqueous solution was 5 parts by weight per 100 parts by weight of the ash) was aged at 20°C for 24 hours to solidify. After solidification, the solidified product was pulverized and classified with a sieve having an opening of 5 mm. 30 g of particles was dispensed from the particles which passed through the sieve, and then subjected to the elution test in the same manner as above.
• Example 172 The elution test was conducted in the same manner as in Example 172 except that the following material was used in place of hydrochloric acid as the additive A.
• Example 172 The elution test results obtained in Examples 172 to 179 above are shown in Table 20 below. TABLE 20 Pb Elution Amount (ppm) Example 172 2.5 Example 173 25 Example 174 4.7 Example 175 14 Example 176 15 Example 177 21 Example 178 21 Example 179 17
• Hydrochloric acid (4.20 g of 36% HCl was dissolved in 20.0 g of water) as the additive A and a tripotassium phosphate aqueous solution (1.0 g of tripotassium phosphate (40 parts by weight per 100 parts by weight of the solid content of the waster glass aqueous solution) was dissolved in 6.0 g of water) as the additive B were simultaneously added to a mixture prepared by adding 6.5 g (solid content: 2.5 g) of the sodium silicate solution (I) to 50 g of the fly ash (I), and then kneaded. The resulting kneaded product was aged at 20°C for 24 hours to solidify.
• the solidified product was pulverized and classified with a sieve having an opening of 5 mm. 30 g of particles was dispensed from the particles which passed through the sieve, and then subjected to the elution test in the same manner as above.
• Example 180 The elution test was conducted in the same manner as in Example 180 except that the following material was used in place of hydrochloric acid as the additive A.
• Example 180 to 187 The elution test results obtained in Examples 180 to 187 above are shown in Table 21 below. TABLE 21 Pb Elution Amount (ppm) Example 180 3.2 Example 181 2.2 Example 182 5.7 Example 183 23 Example 184 18 Example 185 17 Example 186 25 Example 187 19
• the treating material was added to 50 g of the fly ash (I), and then kneaded.
• the resulting kneaded product (the solid content of the water glass aqueous solution was 5 parts by weight per 100 parts by weight of the ash) was aged at 20°C for 24 hours to solidify. After solidification, the solidified product was pulverized and classified with a sieve having an opening of 5 mm. 30 g of particles was dispensed from the particles which passed through the sieve, and then subjected to the elution test in the same manner as above. Further, gelation of the treating material was visually observed to examine the one part stability.
• Example 188 The elution test was conducted in the same manner as in Example 188 except that the following material was used in place of sodium gluconate as the additive E. Further, gelation of the treating material was visually observed to examine the one part stability.
• Example 188 to 196 The elution test results obtained in Examples 188 to 196 are shown in Table 22 below. Further, the results of the one part stability are shown in Table 23 below. TABLE 22 Pb Elution Amount (ppm) Example 188 2.2 Example 189 3.5 Example 190 3.6 Example 191 3.1 Example 192 3.7 Example 193 3.4 Example 194 3.0 Example 195 3.0 Example 196 3.9 TABLE 23 One Part Stability of Treating Material (gelation time (min) of treating material) Example 147 320 Example 188 650 Example 189 670 Example 190 620 Example 191 700 Example 192 680 Example 193 720 Example 194 1,020 Example 195 980 Example 196 890
• the resulting kneaded product (the solid content of the water glass aqueous solution was 5 parts by weight per 100 parts by weight of the ash) was aged at 40°C for 24 hours to solidify. After solidification, the solidified product was pulverized and classified with a sieve having an opening of 5 mm. 30 g of particles was dispensed from the particles which passed through the sieve, and then subjected to the elution test in the same manner as above.
• the elution test was conducted in the same manner as in Example 198 except for changing the aging conditions as follows.
• Example 199 The elution test results obtained in Examples 199 to 204 above are shown in Table 25 below. TABLE 25 Pb Elution Amount (ppm) Example 199 1.6 Example 200 0.27 Example 201 0.11 Example 202 1.8 Example 203 0.30 Example 204 0.14
• aqueous solution prepared by dissolving 1.05 g of hydrochloric acid (36% HCl) (hydrogen ion (H + ) of hydrochloric acid was 50 parts by mol per 100 parts by mol of cations of the water glass aqueous solution) as the additive A and 1.0 g of pentapotassium triphosphate (40 parts by weight per 100 parts by weight of the solid content of the water glass aqueous solution) as the additive B in 20.0 g of water was added to 6.5 g (solid content: 2.5 g) of the sodium silicate solution (I), and the resulting solution was allowed to stand for 5 minutes to prepare a treating material. The treating material was added to 50 g of the fly ash (I) and then kneaded.
• the resulting kneaded product (the solid content of the water glass aqueous solution was 5 parts by weight per 100 parts by weight of the ash) was aged at 20°C for 24 hours to solidify. After solidification, the solidified product was pulverized and classified with a sieve having an opening of 5 mm. 30 g of particles was dispensed from the particles which passed through the sieve, and then subjected to the elution test in the same manner as above.
• the elution test was conducted in the same manner as in Example 205 except for using the following material in place of pentapotassium triphosphate as the additive B.
• Example 205 to 226 The elution test results obtained in Examples 205 to 226 above are shown in Table 26 below. TABLE 26 Pb Elution Amount (ppm) Example 205 2.7 Example 206 2.1 Example 207 2.0 Example 208 2.5 Example 209 2.8 Example 210 3.0 Example 211 3.7 Example 212 4.0 Example 213 3.8 Example 214 3.7 Example 215 3.2 Example 216 4.2 Example 217 3.8 Example 218 4.1 Example 219 3.9 Example 220 4.4 Example 221 1.8 Example 222 1.4 Example 223 2.4 Example 224 2.1 Example 225 3.5 Example 226 3.3
• An aqueous solution prepared by dissolving 1.8 g of dipotassium hydrogen phosphate (hydrogen ion (H + ) of dipotassium hydrogen phosphate was 50 parts by mol per 100 parts by mol of cations of the water glass aqueous solution, and the amount of dipotassium hydrogen phosphate was 72 parts by weight per 100 parts by weight of the solid content of the water glass aqueous solution) in 26.0 g of water was added to 6.5 g (solid content: 2.5 g) of the sodium silicate solution (I). After 5 minutes, the resulting solution was added to 50 g of the fly ash (I), and then kneaded.
• dipotassium hydrogen phosphate hydrogen ion (H + ) of dipotassium hydrogen phosphate was 50 parts by mol per 100 parts by mol of cations of the water glass aqueous solution, and the amount of dipotassium hydrogen phosphate was 72 parts by weight per 100 parts by weight of the solid content of the water glass aque
• the resulting kneaded product (the solid content of the water glass aqueous solution was 5 parts by weight per 100 parts by weight of the ash) was aged at 20°C for 24 hours to solidify. After solidification, the solidified product was pulverized and classified with a sieve having an opening of 5 mm. 30 g of particles was dispensed from the particles which passed through the sieve, and then subjected to the elution test in the same manner as above.
• the elution test was conducted in the same manner as in Example 227 except for replacing dipotassium hydrogen phosphate with the following material.
• Example 227 to 234 The elution test results obtained in Examples 227 to 234 above are shown in Table 27 below. TABLE 27 Pb Elution Amount (ppm) Example 227 4.2 Example 228 3.8 Example 229 2.7 Example 230 4.5 Example 231 3.2 Example 232 16 Example 233 7.3 Example 234 5.8
• the preferred embodiment as the treating material is such that the amount of the acid added which is the additive A in the treating material according to the present invention is such that hydrogen ion (H + ) of the acid is 50 parts by mol or less per 100 parts by mol of cations in the water glass aqueous solution.
• the preferred embodiment as the treating material is such that the amount of the polvalent metal salts added which are the additive A in the treating material according to the present invention is such that the product of the part by mol of the polyvalent metal salts and the number of valency is 50 parts by mol or less per 100 parts by mol of cations in the water glass aqueous solution.
• Example 147 From the comparison between Example 147 and Example 197, it is apparent that the water glass aqueous solution which contains sodium silicate (Na 2 O ⁇ nSiO 2 ) as the main structural component has excellent Pb stabilizing performance as compared with potassium silicate (K 2 O ⁇ nSiO 2 ), and is the preferred embodiment as the treating material.
• sodium silicate Na 2 O ⁇ nSiO 2
• K 2 O ⁇ nSiO 2 potassium silicate
• Example 147 From the comparison between Example 147 and Examples 188 to 196, it is apparent that if any of gluconates, tartarates, benzoates, ligninsulfonates, polysaccharides and bases comprising monovalent cations and hydroxide ions is additionally added as the additive E in the treating material of the present invention, the one part stability of the treating material is apparently improved without decreasing the Pb stabilizing performance; and more preferably, if sodium hydroxide, potassium hydroxide or aqueous ammonia is used as the additive E, the one part stability of the treating material is further improved as compared with other additives.
• Example 188 From the comparison between Example 188 and Comparative Example 26, it is apparent that where the amount of the one part stabilizing agent added exceeds 20 parts by weight per 100 parts by weight of the solid content of the water glass aqueous solution, gel is instantaneously formed, and the one part stability is markedly decreased as compared with the treating material to which a stabilizing agent is not added.
• An aqueous solution prepared by adding 26.0 g of water to 9.1 g (solid content: 3.5 g) of the sodium silicate (I) was added to 50 g of the fly ash (I), and then kneaded.
• the resulting kneaded product (the solid content of the water glass aqueous solution was 7 parts by weight per 100 parts by weight of the ash) was aged at 20°C for 24 hours to solidify. After solidification, the solidified product was pulverized and classified with a sieve having an opening of 5 mm. 30 g of particles was dispensed from the particles which passed through the sieve, and the subjected to the elution test.
• aqueous solution prepared by dissolving 1.0 g of polyaluminum chloride (reagent) (40 parts by weight as the additive C per 100 parts by weight of the solid content of the water glass aqueous solution) in 26.0 g of water was added to 6.5 g (solid content: 2.5 g) of the sodium silicate solution (I).
• the resulting solution was added as a treating material to 50 g of the fly ash (I), and then kneaded.
• the resulting kneaded product (the solid content of the water glass aqueous solution was 5 parts by weight per 100 parts by weight of the ash) was aged, solidified, pulverized, classified with a sieve, and the subjected to the elution test in the same manner as in Comparative Example 29.
• the elution test was conducted in the same manner as in Example 235 except for using the following material in place of polyaluminum chloride as the additive C.
• Examples 235 to 245 and Comparatives 1 and 29 that the Pb elution amount is decreased by even only addition of the water glass aqueous solution as compared with the case of non-treatment, and the water glass aqueous solution has the harmful metal (Pb) stabilizing performance. It is also understood that if the additive C is added, the stabilizing performance is further improved. Further, it is apparent from the comparison between Example 235 and Examples 244 and 245 that sodium silicate (Na 2 O ⁇ nSiO 2 ) has excellent Pb stabilizing performance as compared with potassium silicate (K 2 O ⁇ nSiO 2 ), and is the preferred embodiment as the treating material. Furthermore, it is apparent that sodium silicate having SiO 2 /Na 2 O compositional ratio of 2.0 or more is more preferred embodiment as the treating material.
• a water glass aqueous solution was prepared by adding 26.0 g of water to 13.0 g (solid content: 5.0 g) of the sodium silicate (I). This water glass aqueous solution was added to 50 g of the fly ash (I), and then kneaded. The resulting kneaded product (the solid content of the water glass aqueous solution was 5 parts by weight per 100 parts by weight of the ash) was aged at 20°C for 24 hours to solidify. After solidification, the solidified product was pulverized and classified with a sieve having an opening of 5 mm. 30 g of particles was dispensed from the particles which passed through the sieve, and the subjected to the elution test.
• the elution test was conducted in the same manner as in Example 246 except that the following material was used in place of sodium chloride as the additive D.
• the amount of the monovalent metal salt added as the additive D is 3 parts by mol per 100 parts by mol of cations in the water glass aqueous solution, the improvement of the Pb stabilizing performance is not obtained as compared with the water glass aqueous solution, and if the amount thereof is 150 parts by mol, the resulting solution does not show the embodiment preferred as the treating material. Therefore, it is apparent that the monovalent metal ion of the monovalent metal salt is 5 to 100 parts by mol per 100 parts by mol of cations in the water glass aqueous solution, and this is the preferred embodiment as the treating material aqueous solution. In addition, it is apparent that ammonium chloride is preferred as the ammonium salt of the additive D.
• waste-treating material and the treatment method according to the present invention By treating industrial wastes containing harmful metals using the waste-treating material and the treatment method according to the present invention, harmful metals, particularly Pb contained in the waste incineration fly ash, are stabilized, and the elution amount thereof is decreased. Further, a blend of waste and the treating material, which is obtained as a result of treating the waste according to the present invention can be reused as roadbed materials, aggregates for cement, and the like as a materials that the elution amount of harmful metals is extremely small, and therefore can be valuable resources.

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