Sevenson Environmental Services, Inc.

Maecorp Incorporated

Dhiraj Pal

Karl William Yost

Steven A Chisick

Karl Yost

A process for chemical fixation of radionuclides and radioactive compounds present in soils, solid materials, sludges and liquids. Radionuclides and other radioactive compounds are converted to low-temperature Apatite-Group structural isomorphs (general composition: (AB) (XO ) Z), usually phosphatic, that are insoluble, non-leachable, non-zeolitic, and pH stable by contacting with a suspension containing a sulfate, hydroxide, chloride, fluoride and/or silicate source and a phosphate anion. The Apatitic-structure end product is chemically altered from the initial material and reduced in volume and mass. The end product can be void of free liquids and exhibits sufficiently high levels of thermal stability to be effective in the presence of heat generating nuclear reactions. The process occurs at ambient temperature and pressure.

Reduction of leachability and solubility of radionuclides and radioactive substances in contaminated soils and materials

The present invention discloses a method of forming phosphate mineral species of the apatite family, and the mineral species thus formed, by contacting soil or solid waste material containing leachable lead with a combination of a sulfate reagent that includes one or more reactive sulfate ions and a phosphate supplying reagent that includes one or more reactive phosphate ions. The mineral species are stable, substantially water insoluble and non-leachable under normal environmental conditions. The sulfate reagent is sulfuric acid or alum in liquid or powder form. The phosphate supplying reagent is phosphoric acid, trisodium phosphate, potassium phosphate, mono basic calcium phosphate or dibasic calcium phosphate. In a preferred embodiment, the phosphate supplying reagent is phosphoric acid and the sulfate reagent is sulfuric acid or liquid alum.

Method of forming an insoluble phosphate mineral species

A process for chemical fixation of radionuclides and radioactive compounds present in soils, solid materials, sludges and liquids. Radionuclides and other radioactive compounds are converted to low-temperature Apatite-Group structural isomorphs (general composition: (AB),(XO,),Z), usually phosphatic, that are insoluble, non-leachable, non-zeolitic, and pH stable by contacting with a sulfate, hydroxide, chloride, fluoride and/or silicate source and with a phosphate anion in either a one or two step process. The Apatitic-structure end product is chemically altered from the initial material and reduced in volume and mass. The end product can be void of free liquids and exhibits sufficiently high levels of thermal stability to be effective in the presence of heat generating nuclear reactions. The process occurs at ambient temperature and pressure.

The present invention discloses a method of treating heavy metal bearing process materials and heavy metal toxic hazardous wastes. The invention relates to treatment methods employed to chemically convert leachable heavy metals in heavy metal bearing solid and/or liquid waste materials to a non-leachable form by contacting or mixing the material with a chemical suspension which includes a first component which supplies sulphates, halides, halites, silicates or calcium oxide and a second component which supplies a phosphate anion. The solid and liquid waste materials include contaminated sludges, slurries, soils, wastewaters, spent carbon, sand, wire chips, plastic fluff, cracked battery casings, bird and buck shots and construction debris. The present invention discloses a process comprising a single step contacting of a hazardous waste with a two or three component chemical suspension. The present invention provides a new way of treating a universe of heavy metal contaminated materials at any pH.

Fixation and stabilization of metals in contaminated soils and materials

The present invention discloses a method of treating lead-bearing soils, waste materials and waste material matrixes. The invention relates to treatment methods employed to chemically convert leachable lead in lead-bearing solid and/or liquid waste materials to a non-leachable form by contacting or mixing the material with a chemical reagent that includes a first component which supplies sulphates, halides, halites, silicates or calcium oxide and a second component which supplies a phosphate anion in solution form. The solid and liquid waste materials include contaminated sludges, slurries, soils, wastewaters, spent carbon, sand, wire chips, plastic fluff, cracked battery casings, bird and buck shots and construction debris. The present invention discloses a process comprising a single step mixing lead-bearing hazardous waste with a chemical reagent. The present invention provides a new way of treating a universe of lead-bearing contaminated materials at any pH.

A process for chemical fixation of radionuclides and radioactive compounds present in soils, solid materials,sludges and liquids. Radionuclides and other radioactive compounds are converted to low-temperature Apatite-Group structural isomorphs (general composition: (AB).sub.5 (XO.sub.4).sub.3 Z), usually phosphatic, that are insoluble, non-leachable, non-zeolitic, and pH stable by contacting with a sulfate, hydroxide, chloride, fluoride and/or silicate source and with a phosphate anion in either a one or two step process. The Apatitic-structure end product is chemically altered from the initial material and reduced in volume and mass. The end product can be void of free liquids and exhibits sufficiently high levels of thermal stability to be effective in the presence of heat generating nuclear reactions. The process occurs at ambient temperature and pressure.

Reduction of leachability and solubility of radionuclides and

The present invention discloses a method of treating lead bearing process materials and lead toxic hazardous wastes. The invention relates to treatment methods employed to chemically convert leachable lead in lead bearing solid and liquid waste materials to a non-leachable form by mixing the material with lime, gypsum and/or phosphoric acid. The solid and liquid waste materials include contaminated sludges, slurries, soils, wastewaters, spent carbon, sand, wire chips, plastic fluff, cracked battery casings, bird and buck shots and tetraethyl lead contaminated organic peat and muck. The present invention discloses a process comprising a single step mixing of one or more treatment additives, and a process comprising a two step mixing wherein the sequence of performing the steps may be reversible. The present invention provides a new way of treating a universe of lead contaminated materials at any pH.

Fixation and stabilization of metals in contaminated materials

A highly flexible multi-step treatment technology for chemical fixation and stabilization of leachable chromium, particularly hexavalent chrome, in contaminated soils, solid wastes, concrete, sludge, sand and gravel and waste waters is disclosed. The process comprises reducing hexavalent chromium to chromous (Cr.sup.2+) and chromic (Cr.sup.3+) forms in the presence of water under alkaline conditions and fixing the reduced chromium forms with phosphate. The process reduces Toxicity Characteristic Leaching Procedure chromium levels below the regulatory threshold of 5 mg/l as required by the USEPA.

Fixation and stabilization of chromium in contaminated materials

A two-step treatment process is disclosed for application of lead-toxic wastes to fixate and stabilize leachable lead contained therein. The process employs the use of a sulfate compound, such as gypsum, in a first step; and a phosphate reagent, such as phosphoric acid, in a second step. After thorough mixing and curing, a substantially solid end product is formed in which the lead is chemically fixed and remains in stabilized form for indefinite geologic periods. The process reduces Toxicity Characteristic Leaching Procedure lead levels below the regulatory threshold of 5 mg/l as required by the U.S. Environmental Protection Agency. The waste also beneficially undergoes volume reduction in a short curing time, and is applicable in a variety of situations.

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Chicago Heights, IL, United States of America

Dhiraj Pal