Potential use of a chemical leaching reject from a kaolin industry as agricultural fertilizer

Revista Brasileira de Ciência do Solo

Fabiana Rodrigues Ribeiro²  Fernando Barboza Egreja Filho²  José Domingos Fabris²  Wagner Da Nova Mussel²  Roberto Ferreira Novais¹ 

[1] ,Universidade Federal de Minas Gerais Departamento de Química ,Brazil

关键词: industrial residue;    fertilizer;    kaolin refining;    resíduo industrial;    fertilizante agrícola;    beneficiamento do caulim;   

DOI  :  10.1590/S0100-06832007000500011

来源: SciELO

【 摘 要 】

The industrial refining of kaolin involves the removal of iron oxides and hydroxides along with other impurities that cause discoloration of the final product and depreciate its commercial value, particularly undesirable if destined to the paper industry. The chemical leaching in the industrial processing requires treatments with sodium hyposulfite, metallic zinc, or sulfuric and phosphoric acids, in order to reduce, dissolve and remove ferruginous compounds. To mitigate the environmental impact, the acidic effluent from the leaching process must be neutralized, usually with calcium oxide. The resulting solid residue contains phosphorous, zinc, and calcium, among other essential nutrients for plant growth, suggesting its use as a macro and micronutrient source. Samples of such a solid industrial residue were used here to evaluate their potential as soil fertilizer in an incubation greenhouse experiment with two soil samples (clayey and medium-textured). The small pH shift generated by applying the residue to the soil was not a limiting factor for its use in agriculture. The evolution of the concentrations of exchangeable calcium, and phosphorous and zinc extractability by Mehlich-1 extractant during the incubation period confirms the potential use of this industrial residue as agricultural fertilizer.

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