Fixation and stabilization of metals in contaminated soils and materials

A method of treating lead-bearing soil to stabilize leachable lead contained therein, said method comprising the steps of:

• mixing a lead-bearing soil containing leachable lead with a treatment additive comprising a first component and a second component to form a mixture, wherein said first component supplies at least one member from the group consisting of sulphates, chlorides, fluorides, halites, halides, and silicates, and wherein said second component supplies at least one phosphate anion in solution form;
• and
• curing said mixture for a period of time to form a cured material;
• wherein said lead-bearing soil so treated is substantially solid in form at the end of curing, and the leachable lead level in said cured material is below 5.0 mg/l.

A method of treating a waste matrix of lead-bearing material containing leachable lead and soil to stabilize leachable lead contained therein, said method comprising the steps of:

• mixing said waste matrix with a treatment additive comprising a first component and a second component to form a mixture, wherein said first component supplies at least one member from the group consisting of sulphates, chlorides, fluorides, halites, halides, and silicates, and wherein said second component supplies at least one phosphate anion in solution form;
• and
• curing said mixture for a period of time to form a cured material;
• wherein said waste matrix so treated is substantially solid in form at the end of curing, and the leachable lead level in said cured material is below 5.0 mg/l.

A method of immobilizing leachable lead in contaminated soils or solid waste materials comprising:

• contacting contaminated soils or solid waste materials containing leachable lead with a treatment additive comprising a first component and a second component to form a mixture, wherein said first component includes one or more reactive sulphate ions, and wherein said second component is a phosphate supplying reagent;
• and
• curing said mixture for a period of time to form a cured material;
• wherein said contaminated soils or solid waste materials so treated are substantially solid in form at the end of curing and the leachable lead level in said cured material is below 5.0 mg/l.

A method of immobilizing leachable lead in contaminated soils and solid waste materials comprising:

• contacting contaminated soils and solid waste materials with a combination of sulfuric acid and a phosphate supplying reagent;
• and
• curing said mixture for a period of time to form a cured material;
• wherein said contaminated soils and solid waste materials so treated are substantially solid in form at the end of curing and the leachable lead level in said cured material is below 5.0 mg/l.

A method of immobilizing leachable lead in contaminated soils or solid waste materials comprising:

• contacting contaminated soils or solid waste materials with a combination of a sulfate reagent which includes one or more reactive sulfate ions and a phosphate supplying reagent;
• and
• curing said mixture for a period of time to form a cured material;
• wherein said contaminated soils so treated are substantially solid in form at the end of curing and the leachable lead level in said cured material is less than 5.0 ppm of EP toxic lead.