(1) Classification of filter aids
The auxiliary agent can be divided into a surfactant type and a flocculant type, and can be further classified into an anionic type and a nonionic type surfactant type filter aid according to the difference in ionicity. Both act primarily by lowering the surface tension of the filtrate.
A commonly used anionic surface-active filter aids are OT-type filter aids (succinic acid diester sulfonates). Such filter aids often contain surface active substances which have the ability to lubricate, solubilize and emulsify. This compound and its homologues such as sodium bis(2-ethylhexyl)succinate are the active ingredients of many widely used filter aids. The main disadvantage of such a filter aid for special and more mud containing limonite ore poor adaptability, strong foaming, tends to cake thinning; most aid into the filtrate after filtration, to be used when using the backwater Alkali treatment.
The succinamate sulfonate formed after the amine hydrolysis of the OT type filter aid has better filtration efficiency.
A commonly used nonionic surface-active filter aid (ie, Tweell-nonionic active agent) has a fatty acid ester of sorbitan and an ethylene oxide adduct, and the molecular formula is:
The filter aid has weak dispersibility to the slurry, and most of the filter aid remains in the filtrate after filtration, which brings certain difficulty to the backwater treatment, and has not been popularized due to its high price.
Another nonionic surfactant type filter aid is a higher alcohol and ethylene oxide adduct having the general formula:
Many products based on industrial advanced mixed alcohols (C 6 -C 18 alcohols, especially C 9 -C 14 alcohols) also have good filterability. The amount is generally smaller than the ionic filter aid, and is about 45 to 450 g/ton. The filter cake is loose, and the filtrate is generally used without any difficulty.
The surface-active filter aid has weak dispersibility to the slurry, and most of the filter aid remains in the filtrate, which brings certain difficulties to the return water treatment. At the same time, due to its high price, it has not been promoted yet.
The flocculant type filter aid can not reduce the surface tension of the filtrate, but due to the flocculation effect, the slime can form a stable floc, which can prevent the fine particles from penetrating through the filter cloth or depositing in the pores of the filter cloth without causing the filtrate to be turbid or The filtration speed is reduced. Practice has shown that starch, cellulose or polyacrylamide polymers can significantly increase the filtration rate. But the average moisture content of the filter cake is higher. Under certain conditions, if a suitable flocculant is selected, the effect of reducing the moisture of the filter cake can also be produced. The percentage of the anionic portion of the polymer has a significant effect on the job. The percentage is high and the filtration rate is large, but the filter cake has a high water content. The more the amount added, the greater the filtering rate. [next]
(B) the application of filter aids using anionic surface-active filter aids, such as alkyl containing carbon 10 ~ 24 (preferably C 10 ~ C 16 ) of higher homologues to replace the wetting agent OT, that is, two (2-B Sodium succinate sulfonate is used as a filter aid, and the filtrate can be used as backwater without alkali treatment. When the filter press of 50% copper concentrate containing copper ore yellow, vacuum pressure filter press is shown juice 137.93 kPa (1.406 kg / cm 2).
The succinic acid diester sulfonate and the succinamate sulfonate are added to the iron concentrate slurry for pressure filtration.
The chalcopyrite concentrate was subjected to a vacuum filtration test using a higher alcohol and an ethylene oxide adduct nonionic filter aid.
Since the filter aid has a good effect on the filtration of fine materials, several filter aids have been successfully developed in China in recent years. For example, alkyl and alkaryl sulfonates (anionic surface-active filter aids) have the same effect as OT-type filter aids for the filtration of different types of copper concentrates. Vacuum filtration gauge pressure of 73.33 kPa (550 mmHg), when the sodium dodecylbenzenesulfonate in an amount of 12 g / t, the cake moisture was 11.9% AF 1, AF 2 and AF 3 The type filter aid is a non-ionic galactomannan amine processed from the seeds of legumes, and can be used for filtration of iron concentrate to obtain better effects. The acidified oil-3132 filter aid is a product obtained by acid-base treatment of by-products recovered from chemical plant waste. It has the characteristics of wide source of raw materials, simple production process and non-toxic products. The filtration test was carried out on the flotation iron concentrate: when the dosage was 400 g/ton, the average moisture of the filter cake decreased from 12.3% to 9.9%; when the dosage was 300 g/ton, the filter cake moisture was averaged. 10.2%.Sp505 and CA603 filter aids are all a variety of high molecular organic compounds. When the former dosage is 200 g/ton, the average moisture content of the filter cake of the flotation iron concentrate decreases from 12.8% to 9.16%, and the pH value decreases from 9.2 to 7.2; when the latter dosage is 150-200 g/ton, the iron essence The average moisture content of the mineral cake is less than 9.67%. The attapulgite (a magnesium- rich clay mineral) and the bentonite filter aid are used together with the natural clay mineral and the synthetic organic flocculant to treat the flotation iron concentrate. The filtration process has been significantly improved.
The use of filter aids in the filtration process also presents a "synergistic effect" between the agents, thereby promoting the diversification or mixing of the filter aid components. The mixed drug is more efficient than the single drug. For example, the combination of the polyethylene glycol ether and the OT filter aid, the OT filter aid and the fatty amine, the flocculant and the surfactant type filter aid can improve the filtration efficiency. The pH value of the pulp mainly affects the decomposition of the filter aid. Some filter aids decompose quickly at a certain pH value, and the filter aid is lost. The dispersion of the ore particles in the slurry is also related to the filtration effect, such as alkalinity. High pulp, the slurry is in a highly dispersed state, which is unfavorable for filtration; when using a filter aid, the vacuum gauge pressure should not be lower than 74.66 kPa (200 mm Hg), too low will also affect the filtration effect.
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