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09 May 2022

QUICK LIME IN PAPER INDUSTRY


Quick-lime is used as an active ingredient in the sulphate procedure and as a regenerator agent of reactives used in the Kraft process of paper production, enabling its reuse and exploitation. It is also used as bleach of paper paste, flocculant and neutralising agent in the water treatment process.Calcium oxide, calcium hydroxide, and precipitated calcium carbonate (PCC) have a diverse range of functionality in the paper industry Quicklime and hydrated lime are used in both pulp and PCC manufacturing applications

Calcium carbonates are used in both paper coating and as a paper filler. Calcium oxide or calcium hydroxide is required as a raw material for the PCC manufacturing process QUICK LIME The lime is also a key component of the sulphate process in pulp plants where it is used to recausticize a waste calcium carbonate solution and regenerate sodium hydroxide for reuse in the process.The pulp and paper industry integrates different manufacturing and chemical processes to prepare a variety of products essential to modern society .

o complete these processes, the industry requires many different compounds for a variety of tasks. One of these is lime.The paper and cardboard industries use lime-based coating pigments and fillers such as GCC (Ground Calcium Carbonate). GCC is made from concentrated and fine-ground calcium carbonate and used to make fine paper, cardboard packaging and pulp-based paper.Lime is an important commodity for the pulp and paper industry. Most pulp and paper facilities operate their own kilns and regenerate lime after use. Thus, this industry is primarily a market for “make-up” lime from commercial manufacturers.Pulp and Paper. Lime is an important commodity for the pulp and paper industry. Most pulp and paper facilities operate their own kilns and regenerate lime after use. Thus, this industry is primarily a market for “make-up” lime from commercial manufacturers


Uses of QUICK LIME


SULPHATE PROCESS

By far, the largest application of lime in pulp manufacture is as a causticizing agent in sulphate (Kraft) plants. Here, the waste sodium carbonate solution is recovered and reacted with high calcium lime to generate caustic soda for reuse in the process.

Most large sulphate plants recover about 90-98 percent of the lime by dewatering the waste calcium carbonate mud, then calcining it in rotary kilns.

SULPHITE PROCESS

The ProcessSulfite plants use quicklime to prepare calcium bisulfite, an acid cooking liquor used to digest or dissolve the non-cellulosic constituents of wood chips (paper and pulp stock). This process is on the wane due to waste disposal problems

BLEACHING

In pulp manufacturing processes, the interaction of lime and chlorine is used in the preparation of calcium hypochlorite bleach liquor.

Calcium hypochlorite, the oldest known and lowest cost bleach, is used extensively to bleach the pulp to the desired degree of whiteness

MISCELLANEOUS

Lime is used in the treatment of pulp and paper mill liquid wastes as a coagulant in colour removal, a filtration conditioner, and, to a lesser extent, as a neutralising agent.

It is also used in the recovery of valuable by-products from pulp and paper mill wastes. It is used commercially to recover alcohol, calcium lignosulfonate, and yeast.