One of the most dangerous man-made mineral formations located in the territory of Kazakhstan is disposal areas for granulated phosphorus slag, since its shells contain initially the dangerous gases such as PH3, H2S, HF, etc. Permanent sources of such gases are also Ca3P2 (intrinsically poisonous gas), CaS and CaF2. In the structures of phosphorous ash disposal areas, the chemical and physical-chemical processes contain initially gases, which may be in different modifications. For example: • Phosphene (PH3) in the form: PH3→P2O5→HPO3→H3PO4; • Hydrogen sulfide (H2S): H2S→H2SO3→ H2SO4; • Hydrogen fluoride and silicon tetrafluoride: HF→SiF4→H2SiF6→H2SiO3; • Carbon oxide (СО): СО→СО2→СОСl2. Such chemical processes intensify greatly the anthropogenic effect of phosphorous ash disposal areas on the environment – biogeocoenosis. In addition to the processes related to gas components, in the phosphorous ash disposal areas, the hydration processes occur as a result of interaction of slag with water. Thereat, sub-microcrystalline CSH(I) and calcium are generated. Depth of slag hydration reaches 1…3 μm. Such processes form a thin layer on the surface of slag particles resulting in linking of separate grains into a whole. Therefore, the surface of phosphorous ash disposal areas has the certain strength with cracks, through which water, air, snow, etc. are penetrating into the disposal area. It is evident that granulated phosphorus slag in the form of disposal areas has very adverse impact on the biogeocoenosis, causing the pressing need for their disposal; moreover, such slags are valuable raw material for the construction industry and agriculture only after their decontamination from dangerous gases. Keywords. Granular phosphorus slag, dumps, hazardous gases, chemical reactions.

The paper discusses various ways of activating phosphorus slags by introducing additives for the development of phosphorus slag binders (PSB), replacing cement. Considering that pseudowollastonite is the main mineral of phosphorus slags and without activating components does not possess the binding properties necessary for the production of building materials based on them, we used compositions of small amounts of sodium hydroxide with alkali metal salts, the anions of which form poorly soluble compounds with calcium. When choosing activating components, scarce alkaline additives were replaced by waste from chemical plants, which allows a passing solution of their practical use and environmental problems. The strength at a sodium hydroxide content of 1–4 % after curing of slag samples of various batches was in the range of 50.0–70.0 MPa. Samples of binders of normal hardening at the age of 28 days with a sodium hydroxide content of 0.5; 1.0, 2 and 4 % had the strength of 20.3; 35.4; 45.6; 55.8 MPa, respectively. The effect of the combined presence of alkali and salt is especially noticeable for small amounts of sodium hydroxide. Binders containing a composition of cement with salts under normal conditions and after curing showed a slightly lower strength than in an alkaline medium. With a constant cement content (4 %), the strength indicators increase with an increase in the proportion of the salt additive, reaching at 4 % its maximum value. The effect of the nature of activators on pH was determined. The data obtained indicate the advantages of using PSB and various industrial wastes with a low content of alkaline compounds in the production