Treatment of arsenic-containing waste acid produced from smelting flue gas for acid production
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The disposal of the yellow slag (arsenic filter cake) generated in the treatment of arsenic-containing waste acid produced from smelting flue gas for acid production has always been a problematic issue; moreover, sending it to other manufacturers for treatment incurs considerable costs. It is suggested that the relevant students share their opinions and make full use of their imagination (even a wild idea of yours might provide a new approach to solving the problem), in order to see if it is possible to resolve or minimize this issue as much as possible. I’m just trying to spark interest, hoping to encourage the participation of all the experts out there. My idea is quite simple: to find an appropriate method for treating arsenic-containing waste acid, so that all the precipitates resulting from the removal of arsenic (including the elements that will form precipitates when sodium sulfide is used to treat arsenic) can be removed almost entirely before they react with sodium sulfide. Ensure that over 90% of the yellow slag produced during the arsenic removal using sulfide of calcium is composed of sulfur-arsenic compounds, in order to minimize the amount of arsenic-containing residue and thus reduce the storage space required or the costs associated with handling it.
The treatment of arsenic-containing acid waste is a challenging task in China. The main harmful substances present in such acid waste include sulfuric acid, sulfurous acid, arsenic, fluorine, etc. Generally speaking, in order to reduce the amount of slag generated, quicklime can be used for pre-neutralization to keep the pH at around 4–5. The liquid phase is treated by the sulfidation method or the lime-iron salt method. The solid phase is oxidized to produce gypsum, which can be used as an additive in cement. But I believe this is not the fundamental solution; the real way forward lies in recovering arsenic as arsenic or its oxides, turning waste into a resource. The process is feasible. But most of them involve cost issues – the costs are too high. I am currently working on this. My QQ: 543659370
The treatment process for arsenic-containing sulfonic acid depends on the arsenic content; if the arsenic level is high, arsenic removal should be achieved through sulfidation followed by co-precipitation with iron salts, while if the arsenic level is low, co-precipitation with iron salts alone can be used.
There are many methods for removing arsenic, and they are all relatively mature; the key lies in the recycling of arsenic. Releasing arsenic into the natural environment in any form will have an adverse impact on the environment.
Thank you all for your participation. Hehe, let’s consider the simplest scenario first: assume we just want to reduce the amount of yellow residue (in other words, make the purity of arsenic sulfide in that yellow residue as high as possible). What are the possible methods? That method is the most economical
There are already relevant discussions at http://bbs.hcbbs.com/thread-372952-1-2.html
In three steps: first, remove acidity; then, remove arsenic
The approach to reducing the amount of yellow slag (arsenic filter cake) generated in the treatment of arsenic-containing waste acid produced from smelting flue gas for acid production is correct, but matter cannot be destroyed, so there are limits to the extent of reduction possible. For arsenic-containing wastewater, the treatment method with the lowest cost and the least amount of residue is still sodium sulfide precipitation. If further reduction of the amount of yellow residue is desired, two approaches can be suggested: one is to use sodium sulfide of higher purity; industrial sodium sulfide contains 60% active material and 40% impurities, which end up in the yellow residue. Increasing the purity of sodium sulfide can help reduce the amount of yellow residue ； Secondly, it is sulfided using hydrogen sulfide, without introducing impurities, resulting in theoretically the least amount of yellow slag. The standard treatment process for such wastewater in large domestic factories involves: sulfidation – gypsum production – two-stage neutralization with lime milk + oxidation with iron salts. This process is currently the most economical and reasonable; other methods fail to meet the required standards, result in an excessive amount of hazardous waste residue, and the costs associated with disposing of this waste are beyond what companies can afford. The biggest drawback of this process is the risk posed by hydrogen sulfide gas, as well as the low compliance rates for the slag and the final wastewater. With stricter environmental standards in place, the risk of exceeding these limits increases. However, the upgraded version of this process, namely the \"hydrogen sulfide-free\" high-efficiency sulfidation method, can completely overcome these shortcomings, ensuring full compliance throughout the entire process.