Abstract: According to the invention, the raw mix for producing portland cement clinker comprises a lime component, a clay component, an iron-containing component and a modifying agent. The latter is a cake byproduct readily available at titanium and magnesium works. The percentage by weight composition of the mix is as follows:______________________________________ lime component, 88.3 to 77.8 clay component, 9.2 to 11.2 iron-containing component, 2.0 to 5.0 modifying agent, 0.5 to 6.0 ______________________________________The raw mix according to the invention possesses better properties than conventional mixes. For example, its plasticity is 140 to 160 units, and the degree of mineralization is as high as 19 percent.

Abstract: A process for the preparation of Portland cement clinker resides in that limey, clayey and iron-containing components are ground together. The mix is then homogeneized pelletized, decarbonized at 800.degree. to 1000.degree. C. and roasted at 1200.degree. to 1350.degree. C. Dust sublimates--wastes of the titanium production--are added at the stage of grinding or homogeneization in an amount of 0.5 to 6.0% by total weight of raw mix, and, in case the dust sublimates are added at the homogeneization stage, an aqueous suspension of cakes--wastes of the titanium and magnesium production--is added at the pelletizing stage, at a volumetric ratio of water to cakes of 3-6:1, and in an amount of 10 to 14% by total weight of raw mix.The process according to the invention enables the preparation of clinker exhibiting an improved strength. With the process according to the invention, the degree of decarbonization of raw mix is as high as 35-50%, and roasting temperature is 120.degree.-150.degree. C. lower.