According to an example aspect of the present invention, there is provided a method of replacing with sodium make-up chemicals sodium losses caused by outflows in a pulp mill which employs a kraft process for producing cellulosic pulp, wherein the pulp mill includes a unit for conversion of sulphurous compounds, which is fed with sulphurous substances of the kraft process to convert said sulphurous substances into oxidized sulphurous compounds, said method comprising using sodium sulphate possibly together with other sodium salts as the main make-up chemical, to achieve an essentially sodium hydroxide free feed of sodium make-up chemicals, and at least a part of the sulphur contained in the sodium sulphate make-up chemical being used for producing oxidized sulphurous compounds in said unit for conversion of sulphurous compounds.

A smelt shattering apparatus includes an inlet orifice, an outlet orifice, and a fluidic pathway between the inlet orifice and the outlet orifice. A convergence divergence zone is located between the inlet orifice and the outlet orifice. In one illustrative construction, a first separable section includes the inlet orifice, and a second separable section includes the outlet orifice and a divergence zone of the convergence divergence zone. In some constructions, there may be a second outlet orifice in fluidic communication with the inlet orifice. To provide uniformity over the multiple shatter jets, the first outlet orifice may have a cross-sectional dimension and the second outlet orifice is located a distance of between about 4 and about 10 times of the cross-sectional dimension from the first outlet orifice.

Techniques for growing crystalline calcium carbonate solids such that the crystalline calcium carbonate solids include a volume of 0.0005 mm.sup.3 to 5 mm.sup.3, include a slaker to react quicklime (CaO) and a low carbonate content fluid to yield a slurry of primarily slaked lime (Ca(OH).sub.2); a fluidized-bed reactive crystallizer that encloses a solid bed mass and includes an input for a slurry of primarily slaked lime, an input for an alkaline solution and carbonate, and an output for crystalline calcium carbonate solids that include particles and an alkaline carbonate solution; a dewatering apparatus that includes an input coupled to the crystallizer and an output to discharge a plurality of separate streams that each include a portion of the crystalline calcium carbonate solids and alkaline carbonate solution; and a seed transfer apparatus to deliver seed material into the crystallizer to maintain a consistent mass of seed material.

Techniques for growing crystalline calcium carbonate solids such that the crystalline calcium carbonate solids include a volume of 0.0005 mm.sup.3 to 5 mm.sup.3, include a slaker to react quicklime (CaO) and a low carbonate content fluid to yield a slurry of primarily slaked lime (Ca(OH).sub.2); a fluidized-bed reactive crystallizer that encloses a solid bed mass and includes an input for a slurry of primarily slaked lime, an input for an alkaline solution and carbonate, and an output for crystalline calcium carbonate solids that include particles and an alkaline carbonate solution; a dewatering apparatus that includes an input coupled to the crystallizer and an output to discharge a plurality of separate streams that each include a portion of the crystalline calcium carbonate solids and alkaline carbonate solution; and a seed transfer apparatus to deliver seed material into the crystallizer to maintain a consistent mass of seed material.

The present invention relates to a process for the controlling the sodium and sulfur levels in a pulp mill, comprising the steps of: a) providing a pulp mill stream comprising sulfide and having a total alkali concentration of at least 2 Molar; b) supplying a portion of the pulp mill stream to a reactor comprising sulfide oxidizing bacteria and removing sulfide from the pulp mill stream by subjecting said stream to sulfide oxidizing bacteria in the presence of oxygen, and at a pH in the range 8 to 11, to oxidize the sulfide to elemental sulfur, c) withdrawing from the reactor a treated pulp mill stream comprising sulfur, wherein the portion of the pulp mill stream is mixed with a portion of the sulfide oxidizing bacteria present in the reactor prior to supplying the pulp mill stream to the reactor in step b).

A method of increasing chemical efficiency of chemical additives in a papermaking system includes the steps of providing thick stock pulp comprising soluble lignin, process water, and at least about 2% by weight of cellulosic fiber based on total weight of thick stock pulp, and adding at least one laccase enzyme and at least one organic polymer to the thick stock pulp to reduce the amount of soluble lignin therein. The organic polymer is chosen from cationic polymers, non-ionic polymers and combinations thereof.

The invention relates to a method for clarification of raw green liquor in a sedimentation tank. According to the invention is a part of dregs separated in the sedimentation tank recirculated back into the inflow of raw green liquor, and preferably after passing the dregs through at least one turbulence generator (30, 31) that could break up larger dregs particles into smaller dregs particles, and thus create larger total surface on the dregs particles, improving sedimentation rate in the sedimentation tank. In a preferred embodiment is the recirculated dregs added into the flow of raw green liquor before a flocculant is added into the flow of raw green liquor and mixed recirculated dregs.

Techniques for growing crystalline calcium carbonate solids such that the crystalline calcium carbonate solids include a volume of 0.0005 mm.sup.3 to 5 mm.sup.3, include a slaker to react quicklime (CaO) and a low carbonate content fluid to yield a slurry of primarily slaked lime (Ca(OH).sub.2); a fluidized-bed reactive crystallizer that encloses a solid bed mass and includes an input for a slurry of primarily slaked lime, an input for an alkaline solution and carbonate, and an output for crystalline calcium carbonate solids that include particles and an alkaline carbonate solution; a dewatering apparatus that includes an input coupled to the crystallizer and an output to discharge a plurality of separate streams that each include a portion of the crystalline calcium carbonate solids and alkaline carbonate solution; and a seed transfer apparatus to deliver seed material into the crystallizer to maintain a consistent mass of seed material.

Provided herein is a process for treating dregs for the application thereof as vulcanization activator of rubbers, putting an end to this residue generated in the cellulose industry and providing vulcanized rubbers with similar or enhanced properties in relation to those already known. The process for treating dregs includes the steps of: (a) drying the dregs; and (b) micronization of the dry dregs to an average particle size (d50) from 2 to 45 micrometers. Further provided herein are treated dregs, a use of treated dregs as vulcanization activator, and a process for vulcanizing rubber and the vulcanized rubber.

Techniques for growing crystalline calcium carbonate solids such that the crystalline calcium carbonate solids include a volume of 0.0005 mm.sup.3 to 5 mm.sup.3, include a slaker to react quicklime (CaO) and a low carbonate content fluid to yield a slurry of primarily slaked lime (Ca(OH).sub.2); a fluidized-bed reactive crystallizer that encloses a solid bed mass and includes an input for a slurry of primarily slaked lime, an input for an alkaline solution and carbonate, and an output for crystalline calcium carbonate solids that include particles and an alkaline carbonate solution; a dewatering apparatus that includes an input coupled to the crystallizer and an output to discharge a plurality of separate streams that each include a portion of the crystalline calcium carbonate solids and alkaline carbonate solution; and a seed transfer apparatus to deliver seed material into the crystallizer to maintain a consistent mass of seed material.