Saeed Farrokhpay

A review of polymeric dispersant stabilisation of titania pigment

A review of past and present published works examining the interaction of polymeric dispersants with titania pigment particles is presented. Titania is the most important white pigments currently used in the world and its suspension properties are very important for consumer industries such as paints, papermaking and plastics; if aggregates are present, the end-use properties including gloss, opacity and storage stability will be highly affected. As polymeric dispersants are generally used to disperse titania pigment particles, it is very important to understand the interactions between the pigment particles and polymeric dispersants of varying functionality. Although, in principle, the adsorption of polymers onto titania pigment and influences on pigment dispersion and stabilisation are fairly known, it is nevertheless hardly possible to forecast the behaviour of a given polymeric dispersant in advance, unless to have a broad knowledge of the interaction occurring between pigment and dispersants and effect of dispersant structure upon adsorption. While only titania pigment is discussed, the issues raised may also apply to other mineral oxides such as alumina or zirconia.

The significance of froth stability in mineral flotation--a review.

This paper presents a review of the published articles related to froth stability and its importance in mineral flotation. Froth structure and froth stability are known to play a significant role in determining the mineral grade and recovery achieved in a flotation operation. Froth stability is depending not only on the type and concentration of the frother but also on the nature and amount of the particles present in the system. To date, there is no specific criterion to quantify froth stability although a number of parameters are used as indicators of froth stability. Linking froth stability to the metallurgical performance is also challenged.

A critical review of the growth, drainage and collapse of foams

This review focuses on the current knowledge regarding (i) the mechanisms governing foamability and foam stability, and (ii) models for the foam column kinetics. Although different length scales of foam structure, such as air-water interface and liquid film, have been studied to elucidate the mechanisms that control the foamability and foam stability, many questions remain unanswered. It is due to the collective effects of different mechanisms involved and the complicated structures of foam sub-structures such as foam films, Plateau borders and nodes, and foam networks like soft porous materials. The current knowledge of the effects of solid particles on liquid film stability and foam drainage is also discussed to highlight gaps in our present level of understanding foam systems with solid particles. We also critically review and summarize the models that describe macroscopic foam behaviors, such as equilibrium foam height, foam growth and collapse, within the context of the mechanisms involved.

Froth stability of coal flotation in saline water

Abstract The objective of this study was to identify a practical solution to mitigating over-stable froth problems in fine coal flotation in saline water. The effect of coal particle size, water quality and chemical reagents which can be manipulated in flotation plants, on the froth stability and coal flotation performance was investigated. It was found that froth stability was dependent on the coal particle size, the proportion of process water mixed with de-ionised water and the dosage of the collector or frother. Mixing coarse coal particles with fine coal, diluting process water, and reducing collector or frother dosage all significantly decreased the froth stability. However, only the reduction of reagent usage was recommended as a sound strategy since it did not negatively impact the coal flotation performance while eliminating the over-stable froth problems.

Application of spectroscopy and microscopy techniques in surface coatings evaluation: A review

Abstract: This article presents a review of the published articles related to the novel application of spectroscopy and microscopy methods in paint and coatings quality evaluation. Traditional and simple techniques have been used in paint and coating industry for many years and proven to be effective. However, the paint and coating industry faces new formulations with nontraditional applications. Therefore, the industry needs to adjust itself with the current sophisticated production and testing methods. There are a number of modern microscopy and spectroscopy techniques that can be utilized in the paint and coating industry for a better understanding of the product quality and/or application performance. This, in particular, is highly applicable in modern and nontraditional applications such as nanotechnology and smart coatings. Though importance of spectroscopy and microscopy methods is being increasingly recognized in the industry, there is no current comprehensive review available to highlight the need for novel application of these techniques in surface coatings evaluations.

Significance of Feed Classification by Hydrocycloning on Flotation Copper Recovery

Abstract This paper focusses on the effect of feed classification by hydrocycloning on copper recovery of a complex copper-lead-zinc sulphide ore from Somincor in Portugal. The d80 of the feed sample obtained from the plant was 45 μm. A series of flotation tests and solution/surface analyses were performed. The copper recovery was higher when the feed was reground to d80 of about 18 μm. Surface analysis indicated that the ore surface is heavily oxidized. The presence of oxidized lead and zinc on the surfaces may be effective on copper recovery. The feed was classified using a hydrocyclone to fine and coarse fractions obtaining d80 values of 7 and 65 μm, respectively and flotation tests were conducted on each fraction. Higher copper recovery was obtained from the hydrocyclone products (both fine and coarse fractions) compared to the unclassified feed. It is concluded that the improved flotation behaviour after hydrocycloning is due to surface cleaning.