Activation of fluoranhydrite with various chemical additives for the production of gypsum fiberboards

Preliminary studies of fluoranhydrite as a binder showed that on its own it almost does not harden, intervention in the technological process of basic production is almost impossible, so in order to obtain materials it is necessary to develop ways of modifying it to initiate the binder properties or use “acidic” fluoranhydrite before the neutralization stage. In this work the influence of various additives (sodium sulfate and sodium sulfite, potassium sulfate, copper sulfate, iron sulfate crystallohydrate, alumina aluminate, sodium carbonate) on the properties of fluorine hydrite binders produced by neutralization of sour waste from hydrofluoric acid production with an excess of limestone was studied. In this work to obtain dependences of anhydrite binder technological properties on the number of introduced additives and determine the optimal composition of the binder, as well as create mathematical models of the processes under study and their statistical analysis used mathematical planning of the experiment. As the conducted studies showed the speed of setting of products based on anhydrite binder and their strength mainly depend on the temperature of water and its amount for mixing at the optimum dispersity of the binder. The strength of the samples made from the neutralized waste was found to be in the range of 0.5‒1.2 MPa, and the strength of the samples based on the activated anhydrite binder ― in the range of 5.3‒10.7 MPa that corresponds to the parameters of the material suitable for the production of boards.