Abstract: This invention provides a process for treating chemical woodpulp, or chemical cellulose including cotton linter, including the step of applying an electron processing technology (EPT) step to chemical woodpulp, or chemical cellulose, as the case may be, on an in-line basis to provide control of pulp viscosity or degree of polymerization (DP). The invention also provides a method of process control in treating the aforementioned woodpulp or cellulose, including the step of using radiation dose-viscosity relationship curve for applying an EPT step on an in-line basis. The in-line EPT step may, in one form of the invention, replace and hence eliminate a chemical DP reduction step.

Abstract: A process is provided for the treatment of an acidic aqueous effluent derived from a chlorine or chlorine compound bleaching process. The acidic effluent is reacted with a neutralizing base selected from carbonates, hydroxides and oxides of Al, Cr, Co, Fe, Mg, Mn, and Ni. The neutralized effluent is concentrated and residual base and HCl are subsequently recovered. The concentration of neutralized effluent may be accomplished by passing the neutralized effluent through the cooling tower of the pulp mill.

Abstract: The incinerator product obtained from the incineration of black liquor and other spent liquors from a soda pulping process is treated to remove contaminants including chlorides, sulphates and potassium compounds and to recover a high proportion of the sodium carbonate. The incinerator product is treated with water to form a slurry in which substantially pure sodium carbonate monohydrate is crystallized and a major proportion of the contaminants are dissolved, the sodium carbonate monohydrate is then separated and dissolved sodium carbonate is recovered as a bicarbonate or sesquicarbonate precipitate by carbonation of the solution. The preferred process involves an initial flue gas carbonation of the separated mother liquor after removal of sodium carbonate monohydrate to produce a sodium sesquicarbonate precipitate and a subsequent carbonation of the mother liquor, after separation of the sodium sesquicarbonate therefrom, with pure carbon dioxide to precipitate sodium bicarbonate.