Resource utilization method for fractional precipitation and separation of waste acid with high content of zinc and iron
A step-by-step precipitation and high-content technology, applied in the direction of zinc oxide/zinc hydroxide, iron oxide/iron hydroxide, iron oxide, etc., can solve the problems of shortening the service life of the membrane, increasing the cost of comprehensive wastewater treatment, and irreversible pollution of the membrane, etc. problems, to achieve the effect of low cost, good application prospects, and high economic value of products
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[0026] (1) Preparation of iron oxyhydroxide crystals
[0027] Pour a certain concentration of ferrous solution into a four-necked flask, add 30% lye to adjust the pH to 7, and the temperature of the water bath is 25-30°C, stir and introduce air for aeration, and control the aeration speed; when the pH drops After 2.5-3.5, no change and the solution turns orange, the seed crystal preparation is completed;
[0028] (2) Preparation of iron oxyhydroxide
[0029] Put zinc-containing waste liquid with a zinc-iron ratio of 3:4 (adjustable parameters) into a round bottom flask, and introduce a seed liquid with a solution volume ratio of 5%-20%. Then add 5-15% sodium hydroxide solution at a speed of 10mL / min, the stirring speed is 350rpm, after adjusting the pH to 2-4.5, start to aerate at a certain rate, control the water bath to heat to 40-80°C, The stirring rate was reduced to 250 rpm while continuing to add base to maintain the pH at 2-4.5. When the pH is constant, stop adding a...
Embodiment 1
[0037] Zinc-containing waste acid in the hot-dip galvanizing industry (composition: Fe2+10.701%, Fe3+0.573%, HCl 0.66%, Zn2+4.556%), weigh 512.65g of filtered zinc-containing waste liquid into a 2L four-necked flask Place in a water bath, weigh 52.32g of the seed crystal suspension, add alkali at a speed of 10mL / min in the early stage, and stir at a speed of 350rpm. After the pH is adjusted to 3.5-4, start to blow in air (aeration rate 10L / min ), at the same time, the temperature of the water bath was raised to 65°C, and the stirring was reduced to 250rpm. Continue to add alkali to control the pH at 3.5-4. Not in progress, reaction stopped. Now generate ferric oxyhydroxide, and do not contain iron (iron is completely precipitated) in the filtrate, and zinc content is about 0.695% in the iron biscuit base.
Embodiment 2
[0039] Zinc-containing waste acid in the hot-dip galvanizing industry (composition: Fe2+5.064%, Fe3+0.573%, HCl 0.3%, Zn2+2.273%) Weigh 510.38g of filtered zinc-containing waste liquid into a 2L four-necked flask In the water bath, weigh 51.08g of the seed crystal suspension, add alkali at a speed of 10mL / min in the early stage, and stir at a speed of 350rpm. After the pH is adjusted to 3.5-4, start blowing air (aeration rate 10L / min) At the same time, the temperature of the water bath is raised to 65°C, the stirring is reduced to 250rpm, and the pH is continued to be controlled at 3.5-4 by adding alkali. proceed, the reaction stops. Now generate ferric oxyhydroxide, and do not contain iron (iron is completely precipitated) in the filtrate, and zinc content is about 1.2% in the iron biscuit base.
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