Abstract: A method for controlling an injection moulding press, wherein the injection process is controlled by controlling the injection force, is disclosed. According to the method, the mass (m) of a moulded product is correlated with the viscosity (n) and either the pressure (P.sub.m) of the material in the mould or the injection pressure (P.sub.h), the resulting correlations are processed to define an analytical model expressing the mass (m) of the moulded product in relation to the operating parameters, an injection force control law is derived from the analytical model on the basis either of the pressure (P.sub.m) of the material in the mould or of the injection pressure (P.sub.h), and the press injection force is controlled on the basis of the analytical model.

Abstract: A complex composition formed by the product resulting from the action of urea on a sludge of petroleum origin containing by weight from 50 to 99% of sulfuric acid and from 1 to 20% of organic residues. The acid sludge may contain water and often comes from an alkylation reaction. This composition can be used as a source of fertilizing material or as a component of a fertilizing formulation.

Abstract: The method relates to the production of phospho-nitrogenous products soluble in neutral ammonium citrate and wherein free urea does not remain in significant amount in such products. Most of the free urea is involved in a ureic combination of calcium sulphate. Tricalcic phosphate is reacted with a reactant obtained by mixing sulfuric acid and urea. The process is particularly useful for the manufacture of fertilizers.