JPS5817814A - Improving agent for filtration and dehydration properties of water slurry of metallic hydroxide - Google Patents

Abstract

PURPOSE:To improve dehydration efficiency by using the nonionic surfactant expressed by R-O-(AO)n-H in a filtration and dehydration stage for water slurry of metallic hydroxides. CONSTITUTION:A titled improving agent for filtration and dehydration properties consisting of the nonionic surfactant expressed by R-O-(AO)n-H wherein R is 4- 24C alkyl groups, alkenyl groups, alkyl aryl groups having 8-20C alkyl groups, distyrenated phenyl groups or dibenzylated phenyl groups, A is 2-4C satd. alkylene groups, and (n) is 1-100. When said improving agent is added to water slurry of metallic hydroxides which are insoluble in water or hardly soluble in water, dehydration efficiency is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a filtration and dehydration improver for water slurry of water-insoluble metal hydroxides (including water-releasable metal hydroxides),
More specifically, the present invention relates to a filtration and dehydration improver comprising a type of ionic surfactant used to efficiently and economically remove water from an aqueous slurry of water-insoluble metal hydroxide particles. .

In general, wet water-insoluble metal hydroxide particles are characterized by their metal type, production conditions, particle size, shape, surface condition, and -
Although it varies depending on the over-dehydration conditions, etc., it still contains a considerable amount of water even after being over-dehydrated. In particular, when a metal hydroxide is obtained by making a metal salt solution alkaline and precipitating it, a hydroxide containing a large amount of water with an inconsistent compositional formula is often obtained. Kd vacuum (reduced pressure) filtration dehydration is often used, but still some water remains. For example, when an aqueous aluminum hydroxide slurry is dehydrated by vacuum furnace dehydration, an aluminum hydroxide cake containing 8 to 16 parts by weight of water is generally obtained.

After being filtered and dehydrated, the wet metal hydroxide is either directly manufactured into a product as a hydroxide, or is often further calcined to be manufactured into a product as a metal oxide. However, the wet metal hydroxide contains In the case of products in the form of hydroxide, the moisture content during storage may become uneven, resulting in disadvantages such as a decrease in the commercial value of some products or an increase in transportation costs. In the case of a physical product, there are disadvantages such as increased fuel costs required for the firing process due to the heat of evaporation of the water contained in the wet metal hydroxide.

In particular, the recent rise in fuel prices has significantly increased their manufacturing costs, so reducing energy costs has become an important issue.

Therefore, there is a need for measures to efficiently and economically reduce the water content in metal hydroxides to below the current level in the filtration and dehydration process of water slurry of metal hydroxides. Attempts have been made to improve the dewatering conditions, but it is still desirable to further increase the dehydration efficiency by adding some kind of additive.

As a result of intensive research under the current circumstances, the present inventors have found that when temporarily dehydrating an aqueous slurry of water-insoluble or poorly water-soluble metal hydroxides, if the following is added and used, it can be done extremely efficiently and economically. 0 R-0 (-AO9II (I)C In the formula, R
an alkyl group having a ti-order prime number of 4 to 24, an alkenyl group, an alkylaryl group having an alkyl group having 8 to 200 carbon atoms,
A is a distyrenated phenyl group or a dibenzylated phenyl group, A is a saturated alkylene group having 2 to 4 carbon atoms,
n is an integer of 1 to 100, preferably 1 to 10. ) As a raw material for the nonionic surfactant represented by the above general formula (RI), either natural alcohol or synthetic alcohol may be used.Moreover, 0 in formula (1) is ethylene oxide, propylene oxide, It may be either a single block of butylene oxide or a random block of two or more types of silica.

The method for producing the interfacial agent represented by the general formula (2) is not particularly limited, and may be produced by various conventionally known methods.

Examples of water-insoluble or poorly water-soluble metal hydroxides for which the temporary dehydration improver of the present invention are used include -M group metal hydroxides such as magnesium hydroxide, calcium hydroxide, strontium hydroxide, and barium hydroxide. Oxides; -M group metal hydroxides such as aluminum hydroxide, gallium hydroxide, indium hydroxide; germanium water 7w1, tin hydroxide,
■-Mu group metal hydroxides such as lead hydroxide; ■group metal hydroxides such as iron hydroxide, cobalt hydroxide, nickel hydroxide;
Examples include M-B group metal hydroxides such as zinc hydroxide; IV-B group metal hydroxides such as titanium hydroxide. These metal hydroxides may be particles having an ionic diameter of about 1 to 1000 μm, or porous particles formed by condensation thereof.

The temporary dehydration improver of the present invention can be added at a predetermined concentration to the water slurry before the final filtration and dehydration process under temporary dehydration conditions for the metal hydroxide water slurry, or added to the washing water. can be used. For example, when manufacturing a tf filtration dehydration cake from a metal hydroxide that has been made into a cis slurry using a manufacturing process liquid, it is sufficient to add a temporary dehydration improver to the process liquid, or When the wet cake obtained by dehydrating the seeding solution is once washed with steamed water or the like and then subjected to temporary dehydration again, a K filtration dehydration property improver can be added to the washing water. In general, metal hydroxide manufacturing solutions have high ionic strength and are often alkaline aqueous solutions or have high salt astringency, so purified water etc. are used in the washing water to improve filtration and dehydration properties. It is advantageous to add an agent.

The amount of the temporary dehydration improver of the present invention added to the metal hydroxide solution varies depending on the type of metal hydroxide, the particle size distribution, the state of the particle surface, the temporary dehydration conditions, etc. ), about 10 p per unit weight of dry metal hydroxide.
The preferred addition amount is pH ~ about 11,000 pp 11 degrees, and the consistency is from s e ppm to about gooppm in terms of effectiveness and economy. According to the results of the research conducted by the present inventors, the effect of promoting dehydration initially improves as the amount added increases, but it reaches a saturation state at a certain concentration, and if the amount added beyond this point increases, the effect slightly reverses. Promotion of dehydration Most of the single molecules of metal hydroxide particles are adsorbed on the particle surface, making the surface hydrophobic and facilitating dehydration, but above the saturation concentration, excess molecules are eluted into the F solution, resulting in even higher levels of dehydration. It is thought that the adsorption of Fi2 molecules progresses partially in the concentration range and becomes hydrophilic again, reducing the dehydration promoting effect. Therefore,
In other words, if the amount of the filtration and dehydration improver is used is slightly smaller than the saturated adsorption amount, the filtration and dehydration improver will hardly be eluted into the F solution and the foaming property can be suppressed. Even in the case of circulating the F solution in a closed system of production, there is an advantage that there is little accumulation of temporary dehydration improver in the process solution due to long-term use.

For filtration and dehydration of metal hydrate water slurry, filtration 1! There are methods that promote dehydration by suction from the side and reduced pressure (vacuum), and methods that promote dehydration by applying pressure from above, but the temporary dehydration improver of the present invention can be used in either method. can be done. When the metal hydroxide particles are fine particles, a common polymer flocculant such as polyacrylamide or partially hydrolyzed waste thereof can also be used.

Next, an explanation will be given with examples, but the wAFi of the present invention is not limited to these examples.

Example A 1 molar aqueous solution of sodium hydroxide 10011j and aluminum hydroxide powder 60f were mixed and stirred at a specified rotation speed for 60 seconds, then a Puchner funnel was placed with V paper (A2 manufactured by Toyo F Paper) with a diameter of 7 mm. Pour on top. After leaving it for 30 seconds,
Suction F and ventilation are performed for 1 minute at a reduced pressure of 42011 Hg. Subsequently, 100 sIj of washing water (distilled water) containing a predetermined amount of filtration and dehydration improver was poured onto the cake after filtration, and suction filtration and aeration were performed for 5 minutes at a reduced pressure of 4201111Hg. The obtained wet aluminum hydroxide cake 50F is weighed, dried at 110° C., and its constant weight (dry cake weight) is measured. - Calculate the water content of alonium hydroxide after over-dehydration using the following formula.

Table 1 shows the results of a blank test in which 50 ppm (by weight) of various dehydration improvers were added to aluminum hydroxide powder in washing water at 70°C, and at the same time, no dehydration improvers were added. Ta.

Table 1

Claims (1)

[Scope of Claims] 1 A filtration and dehydration improver for water-insoluble or poorly water-soluble metal hydroxide aqueous slurry consisting of a nonionic surfactant represented by the following general formula (1) 0R-0÷mO+nH(1 ) (wherein, R is an alkyl group having 4 to 24 carbon atoms, an alkenyl group, an alkylaryl group having an alkyl group having 8 to 20 carbon atoms, a distyrenated phenyl group, or a dibenzylated phenyl group, and A is an alkyl group having 2 to 24 carbon atoms. O) which is a saturated alkylene group of ~4 and is an integer of Ln#i1~10G