Design of plant for extrusion of pigment pastes

2017-06-22T11:08:02Z (GMT) by Festus B. Ogunnubi-Johnson
In the light of the requirement for a controllable and reliable extrusion plant for preforming various types of inorganic pigment into spaghetti shape onto a convective band dryer to facilitate drying, a study of the preforming method currently in use by the sponsors has revealed that the screw extruder being used cannot perform this function satisfactorily. The main reason being the thixotropic nature of the pigments. They do not readily tolerate mixing or working, which is inherent in the screw extruder. This necessitated a study of other preforming methods. The thesis reviews the available methods of preforming, existing theories on extrusion of material, and various extruder concepts generated during the initial stages of the project. The concept chosen is discussed. A mathematical model based on test results carried out on a Laboratory model of the chosen extruder concept and tile complete design of the full scale extrusion machine, together with its charging units and the plants' control system is presented. An analysis of the performance tests carried out on the new plant is discussed. The thesis concludes with a comparison between the new plant and the screw extruder in current use regarding their performances and product qualities. Proposals for further work and test are also made.