Optimisation Of Process Parameters In High Energy Mixing As A Method Of Cohesive Powder Flowability Improvement

Abstract

Flowability of fine, highly cohesive calcium carbonate powder was improved using high energy mixing (dry coating) method consisting in coating of CaCO3 particles with a small amount of Aerosil nanoparticles in a planetary ball mill. As measures of flowability the angle of repose and compressibility index were used. As process variables the mixing speed, mixing time, and the amount of Aerosil and amount of isopropanol were chosen. To obtain optimal values of the process variables, a Response Surface Methodology (RSM) based on Central Composite Rotatable Design (CCRD) was applied. To match the RSM requirements it was necessary to perform a total of 31 experimental tests needed to complete mathematical model equations. The equations that are second-order response functions representing the angle of repose and compressibility index were expressed as functions of all the process variables. Predicted values of the responses were found to be in a good agreement with experimental values. The models were presented as 3-D response surface plots from which the optimal values of the process variables could be correctly assigned. The proposed, mechanochemical method of powder treatment coupled with response surface methodology is a new, effective approach to flowability of cohesive powder improvement and powder processing optimisation.

Prospective Application of Response Surface Methodology for Predicting High-Energy Mixing Process Conditions towards Fine Powders Flow Improvement

“…Similar response functions, representing the influence of mixing speed and time, as well as the amounts of Aerosil and isopropyl alcohol on the angle of repose and the compressibility index values for finely ground Calcium carbonate powder, were obtained earlier [7] and for coded levels of variables they are as follows: The response functions for both Apyral (Eqs. 3 and 4) and Calcium carbonate (Eqs.…”

“…Regardless of the practical importance of Apyral, there is a serious problem with handling this material due to its cohesiveness and poor flowability. For optimisation procedure, some earlier results obtained for the Calcium carbonate powder (Chempur, Poland) was also included [7]. The physical properties and particle size distribution of both powders are given in Table 1.…”

Melamine cyanurate surface treated by nylon of low molecular weight to prepare flame‐retardant polyamide 66 with high flowability

“…This parameter reflects the flowability of powder and can be used to evaluate the effect of surface modification. Generally, the cohesive powders require greater flow energy because the entrained air is able to escape, leaving a stiffer material, more resistant to flow . Therefore, smaller flow energy means smaller flow resistance of the tested powder, and it implies that the powder can be more easily dispersed.…”

Import Substitution in the Industry of Water Supply and Sanitation

“…Confusers are made in the form of straight round hollow truncated cones. Cones large bases are turned towards the rotation [11]. On the lower base of the outer confusers mounted coaxially to them hollow cones made in the form of a Laval nozzle.…”