Optimising rational chemical analysis for quantitative determination of the composition of clay in soils

A fractional (rational) chemical analytical method is proposed by which the material composition of clay rocks can be quantified and the clay-forming minerals present can be characterised. Subjecting raw clay to this procedure allows for the determination of the chemical composition of its fine-grained fraction, the amount and composition of exchangeable cations, water-soluble salts, carbonates and colloidal minerals, and the amount of amorphous silica and free quartz. A new, effective method is proposed for the qualitative and quantitative evaluation of the amorphous component in clays. This involves extracting colloids by treating the clay fractions with Tamm's reagent, a buffer solution of oxalic acid and ammonium oxalate with a pH of 3.25. Additionally, through calculations based on the results of chemical analyses, the illite content (derived from the content of non-exchangeable potassium oxide) and the chemical composition of the clay residue are determined. This enables the rock-forming clay mineral to be characterised and its structural chemical formula to be determined. This allows prediction of the physico-chemical and technological properties of the clay.