The problem of removing copper from wastewater
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In highly acidic wastewater (with a salt acidity of 19%), the copper ion concentration is about 0.5%. Currently, two methods are known: 1) Adding Na2S to remove copper by forming copper sulfide; the problem is that copper sulfide has little practical use and is not worth recovering. Moreover, controlling the amount of sodium sulfide added is also a problem; in order to remove all the copper, an excess of sodium sulfide is used, which results in the production of hydrogen sulfide ； 2. Resin adsorption is used, but the problem is that such strong acidity makes it difficult to adsorb the substance; adding alkali for adjustment results in high costs. I would like to ask if there is a better way to remove copper? Or what are some good uses for copper sulfide?
I don’t know in what compound your copper exists; first adjust the pH to neutral, then filter and use resin for adsorption
The copper in water is in the form of copper chloride, but the salt acidity level is too high, at nearly 20%; almost 300 tons of this substance are present each day. If alkali is used to neutralize it, the cost involved is too high
"The hydrogen sulfide-free \"sulfidation-based copper removal technology\" has been tested on an industrial scale in a sulfuric acid medium at a concentration of around 20%; the chloride ion concentration in this medium was approximately 2000 mg/l, with a treatment rate of 30 cubic meters per hour. In a single reaction, copper ions can be reduced to levels below the detection limit of ICP analysis (i.e., to the level indicated as \"not detected\" in the analytical report). “The \"sulfur-free\" sulfidation technique refers to a process in which no hydrogen sulfide is released at all during the reaction. In fact, during the copper removal process, hydrogen sulfide is a key substance; its presence is necessary in order to remove copper effectively, otherwise copper cannot be removed completely. Therefore, when using the sulfurization method for copper removal in wastewater, the acidity level of the water should be somewhat high. If the acidity is too low or if the pH of the water is neutral or slightly alkaline, it becomes difficult to achieve the desired results using this sulfidation method for copper removal. “The “hydrogen sulfide-free” copper removal by sulfidation technique is a method that makes clever use of hydrogen sulfide to improve the efficiency of sulfidation. Copper smelting companies use this technique to produce copper sulfide slag, which is then sent back to the pyrometallurgical copper smelting process for recovery; you may also consider accumulating this copper sulfide slag and selling it to copper smelting companies. Copper removal under alkaline conditions presents two problems: first, the neutralization cost is too high; second, under alkaline conditions copper exists in the form of copper hydroxide, and the solubility of copper hydroxide is much higher than that of copper sulfide. Its natural solubility may result in wastewater containing excessive levels of copper, failing to meet discharge requirements. Detailed technical information can be discussed on the site.
Oh then the neutralization method can’t be used
So how do you address the problems of fine precipitation of copper sulfide particles and difficult filtration?
In wastewater containing sulfuric acid, the precipitated flocs are large in size; there has been no issue with fine particles, and their natural sedimentation properties are also good. Solid-liquid separation can be achieved using conventional filtration methods.
I’m working on electrolytic cation exchange; I’ve been dealing with wastewater treatment lately and still don’t understand it well, so I’d like to learn from everyone*
Membrane separation can be used to separate hydrochloric acid from copper chloride; the resulting hydrochloric acid has a relatively high purity and can be recycled.
If resin adsorption treatment is indeed considered, chelating resins can be used for this purpose. It depends on whether the customer is willing to accept the formation of copper ammine. In high-salt and acidic conditions, resin adsorption can be employed for treatment, but acid regeneration cannot be used for regenerating the resins; instead, ammonia water should be used for that purpose. The adsorption capacity of this resin can still reach 350–40 g/l, but it is relatively more expensive compared to ordinary chelating resins; it’s not clear whether customers will be willing to accept that. If necessary, small experiments can be arranged to see the effects of them. We are Xi’an Lanxiao Technology, the largest manufacturer of specialty resins in China. It is also the only listed company in the resin industry.