DUAL FLOCCULANT SELECTION IN THE FIBER CEMENT PROCESS

摘要

It is well known that flocculants are required in the manufacturing process of asbestos free, PVA fibre cementrnproducts. Whilst there are some guidelines for the suitable selection of flocculants, there are also variedrnopinions on the choice of the right flocculants to be used in the process. Simply put, there is no universalrnsolution. Each process needs to be individually evaluated, based on the characteristics of the machines and therntype of mix formulations.rnThis paper deals with the unique approach of considering the use of multiple flocculants.rnTypically flocculants are expected to perform two distinct functions within the closed loop Hatcheck process;rnthese are solids retention in the vats and settling in the cone tanks.rnBy splitting the process and evaluating the individual requirements, we are better able to understand therninfluences on the process and make a more suitable selection of flocculants.rnFurthermore, the significant influence that wet waste has on the selection of the polymer and the resultantrnretention characteristics in the vat is presented.