Cellulose and Related Modified Products

As mentioned above, cellulose can be considered as a depressant. In addition, cellulose can also flocculate mineral particles by bridging of organic macro-molecule chains. The structure of cellulose can be given by the following  

Various modified celluloses can be prepared from cellulose by introducing different functional groups. For example, carboxymethyl cellulose (or CMC) is prepared from cellulose by introducing carboxymethyl group. Cellulose xanthate (or CX) is prepared from cellulose by introducing dithiocarbonate radical [1]. Sulfonated cellulose sulfonate and ethoxyl cellulose are called CSE and CEH, respectively, for short. The stmctures of CMC, CX, CSE, and CEH can be seen as follows  

The value of n of CMC is 450-550. The degree of substitution of CMC is 40-50. The degree of substitution of CSE is about 50. Various modified celluloses are alkali soluble. 

Take CMC for example, the preparation and processing is as follows. Firstly, the raw materials (such as straw, reed, and cornstalk) are treated with 30 wt% NaOH. Then the alkali cellulose is etherified with monochloroacetic acid. The main reactions are given as follows  

In general, CMC and CEH can depress gangue via flocculation. The performance of sulfurated CMC is similar to that of CMC. The depressing performance of sulfurated cellulose is shown in Fig. 5.1. It can be seen that the depressing performance of anionic sulfurated cellulose is relatively better under alkaline conditions. 

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