Leach X

LeachX is a two-part stabilization technique that takes advantage of two chemical processes to immobilize heavy metals in soil.

The first additive is designed to render heavy metals insoluble by reacting free metal ions with a mixture of sulfide, carbonate and hydroxide anions at an elevated pH. The second additive provides for pozzolanic reactions to proceed to immobilize the metals within a calcium silicate hydrate.

Certain materials undergo what is known as a pozzolanic reaction. A pozzolanic reaction takes place in the presence of lime (calcium oxide, CaO), silicate, alumina and water to produce reaction products that are cementitious in nature. Materials that undergo such reactions are collectively known as pozzolans. They are frequently amorphous (glassy) in nature, with a chemical composition rich in silica and, to a lesser degree, alumina. Examples of pozzolans include pulverized-fuel ash, condensed silica fume, metakaolin and glass cullet. Usually the main product of a pozzolanic reaction is a material known as calcium silicate hydrate (C-S-H) gel. The LeachX formula utilizes this type of material bonding to immobilize the heavy metals after they have undergone the reaction that places them in an insoluble form.