ADDITIONAL REQUIREMENTS TO THE GYPSUM-ANHYDRITE AS A REGULATOR OF CEMENT SETTING TIME
Cement plants in Central, North-West and Southern Federal Districts, as well as in the Volga region use untreated calcium sulfate from deposits of Tula, Nizhny Novgorod, Astrakhan, Arkhangelsk regions, and Tatarstan as a regulator of cement setting time. Searching for more accessible sulfate-containing materials of natural origin is of interest for a number of cement enterprises due to a huge transportation range of natural calcium sulfate dehydrate.
Typically, deposits of natural sulfate-containing materials are characterized by nonhomogenity of the mineralogical composition, i.e. the presence, along with natural water-soluble calcium sulfate dihydrate, of gypsum-anhydrite stone and anhydrite in which the content of soluble and insoluble in water forms of calcium sulfate varies widely.
Usage of the gypsum-anhydrite, anhydrite, etc., in cement production required to develop additional criteria to determine their optimum content in cement which provides standard terms of cement setting without loss of cement stone strength during hardening and performing appropriate control of these criteria, both at a gypsum quarry and directly during the production of cement.
It is stated that when gypsum rocks like the gypsum-anhydrite or anhydrite are used as a regulator of cement setting time, the water-soluble sulfur oxide, the mass concentration of which in a regulator of cement setting time is to be 32 abs.% at least, should be taken as the additional control parameter (with respect to the parameters specified by GOST 4013-82 "The gypsum and gypsum-anhydrite stone for the production of binding agents").
JSC NIICEMENT offers to set optimum parameters of cement production and ensure appropriate procedures of their control within the material composition of cement and initial regulator of setting time for each particular enterprise using sulfate-containing materials with insoluble anhydrite forms as a regulator of setting time.
This offer is carried out upon customers’ request by the Laboratory of Cements and Chemical-Analytical (Testing) Lab. of JSC NIICEMENT that has a state accreditation - Accreditation Certificate of Testing Laboratory (Center) No. РОСС RU.0001.22CM40 (No. 000473).
Ul. Pleshcheevskaya, 15, Podolsk, 142101 Moscow region, Russia
Alla V. Shutova
Head of Laboratory of Cements
Irina E. Kovaleva
Head of Chemical-Analytical Lab.