Patent ID: 8617354
Filing Date: 2013-12-31
Classification: C08B,C08H,D21C,Y02P

Abstract:
1. A process for manufacturing shaped cellulose material from lignocellulose comprising the steps of: a) providing a feed of comminuted lignocellulosic material comprising cellulose, hemicelluloses and lignin; b) separating lignin from lignocellulosic feed material by cooking the material at a temperature from between about 110 to 200° C. for a time period of from about 1 hour to 6 hours in an aqueous solution comprising soluble alkali, alkali earth metal or phosphorous compounds, thereby forming a first stream of solid material enriched in cellulose and a second spent liquor stream rich in dissolved lignin; c) treating the first stream enriched in cellulose from step b) by at least one of oxygen delignification, bleaching, and alkali extraction, to form a cellulose pulp with a lignin content below about 2 wt %; d) treating the second spent liquor stream from step b) comprising dissolved lignin, alkali, alkali earth, phosphorous or sulfur compounds, in a separate chemical recovery system comprising one or more chemical recovery units selected from the group consisting of a spent liquor concentration unit, a gas generator unit, a recovery boiler unit, and a causticising unit, wherein one or more of fresh alkali, alkali earth metal, phosphorous and sulfur compounds are recovered and reformed; e) dissolving the cellulose pulp having a lignin content below about 2 wt % from step c) in a solution comprising one or more of alkali, alkali earth, phosphorous, sulfur and molten salt compounds, the solution optionally comprising one or more additives, thereby forming a substantially homogeneous solution comprising dissolved cellulose, thereafter shaping or coagulating the dissolved cellulose into fibers, films or cellulose derivatives, and optionally washing the shaped or coagulated cellulose; f) discharging spent chemicals from at least one of: g) recycling the spent chemicals in one or more units of the chemical recovery system of step d); wherein the spent chemicals are recovered and reformed; h) using fresh cellulose dissolving and/or cellulose shaping chemicals recovered from the chemical recovery system in step g) in the respective cellulose dissolving and/or cellulose shaping steps in e).