Synergistic Interactions A Case Study

Synergistic enhancement of flotation performance has been observed in batch flotation tests with a low

Figure 2 The mass loading per bubble for bubbles of average diameter of 1.2 mm of pyrite with equimolar amounts of potassium n-butyl xanthate (PNBX), dithiocarbamate class of reagents (DTC) and the 90 : 10 mixture of collectors added at pH 4.

.^^Mixture

' \

; ' DTC

/ V

\

r*-Collector addition -

1

1 1

100 0 100 200 300 400 500 600

100 0 100 200 300 400 500 600

Figure 3 The difference in heat flux measured when equimolar amounts of potassium n-butyl xanthate (PNBX), dithiocarbamate class of reagents (DTC) and 90 : 10 mixture of collectors are added to pyrite at pH 4.

grade pyrite ore using thiol collectors at pH 4. The collectors tested were potassium «-butyl xanthate (PNBX) and an alkyl dithiocarbamate collector. Performance was analysed using grade-recovery data as well as water and mass recoveries and the rate of sulfur recovery. The froth surface was analysed using digital image analysis. In all experiments the total molar concentration of collector was constant.

Figure 1 shows the batch flotation results as represented by sulfur grade at 80% recovery, the sulfur recovery at 25 % grade and the water recovery, all as a function of mole ratio of components. It is clear that the grades and recoveries are greater than would be expected from a merely linearly additive effect and are synergistically enhanced. Obviously pure collectors may not show linearity with respect to dosages but in the present case the dosages were in the range where these differences were minimal. The change in water recovery, however, was linearly proportional to the molar contribution of the components and clearly the synergistic effect was only influencing the behaviour of the solid particles. Digital image analysis of the froth showed that, when the mixture of collectors was used, the froth was more mobile and the froth surface bubble size was larger. This may be due to the frother-collector interactions, decreasing froth stability, increasing drainage of entrained material and increasing the grades obtained.

In order to elucidate the mechanisms of synergism, the extent of bubble loading and the heats of adsorption were measured for the respective collectors and collector mixtures using pure pyrite at pH 4,

(Figure 1). Figure 2 shows that, for bubbles of average diameter of 1.2 mm, increased bubble loading resulted from the use of a mixture of collectors and Figure 3 shows that when a mixture of collectors was used there was a stronger adsorption than in the case of the pure xanthate, where multilayer adsorption of dixanthogen is indicated, and in the case of dithiocar-bamate where pseudo-monolayer adsorption is indicated. In this example, the synergistic effect observed is attributed to increased mineral hydropho-bicity, which is thought to be due to the weakly adsorbing dixanthogen adsorbing in multilayers around the strongly adsorbing dithiocarbamate, which acts as a sort of anchor on the surface of the mineral particle. The ultimate result is an increase in bubble loading, an improvement in froth characteristics and a greater grade and recovery.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

Get My Free Ebook


Post a comment