Discussion on the use of cobalt extraction systems for removing calcium and magnesium
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Currently, affected by the financial crisis, smelting enterprises are seeking every possible way to improve their processes and reduce costs through various means. In cobalt smelting systems, raw materials with high calcium and magnesium content are commonly encountered. The traditional separation method involves using sodium fluoride for chemical precipitation to remove calcium and magnesium; only after this step is the material suitable for use in the P204 and P507 processes. In actual production, however, the efficiency of sodium fluoride in this process is not high, which results in high costs merely for sodium fluoride itself. The currently popular technical improvement in various factories: using extraction methods to separate nickel from cobalt while removing calcium and magnesium can **reduce production costs**. Everyone here can discuss the process control and production experience related to calcium and magnesium removal by extraction. Our company’s current approach is as follows: The copper extraction raffinate, with a pH of 1.5–2.0, is directly fed into the cobalt P204 extraction process. By controlling the pH at the feed inlet to around 3.0, calcium is preferentially extracted and separated, ensuring that the raffinate meets the required standards. The P204 raffinate contains 1.0–3.0 g/l of magnesium, and it is sent directly to the P507 system. Since P507 does not have a high separation coefficient for cobalt and magnesium, a large amount of magnesium ends up in the organic phase. In the washing stage, this mixture is washed using a solution with a high cobalt concentration in order to separate cobalt from magnesium, taking advantage of the large difference in concentrations to enhance the separation efficiency. Although the washing effect meets the requirements, it is unstable, which affects production volume. Everyone can discuss their experience in process design for calcium and magnesium removal by extraction.
Your current method is likely one of the more advanced ones available; by entering terms such as “calcium and magnesium removal by extraction” in the advanced search bar at http://www.sipo.gov.cn/sipo2008/, you can find relevant patents.
Was Huayou the first to try it? There are two issues: First, during the cleaning of the 204 anti-contamination sections, calcium and the sulfate ions carried along can form precipitates; could this lead to blockages over time? Second, how much can be saved in costs by extracting calcium and magnesium? The most significant factor is probably the ecological impact – it is more environmentally friendly, with no fluoride-containing wastewater released
Upstairs, you must be an employee of Hua You, right?:) What range can calcium and magnesium levels be kept within in your place?
Our company does not pre-treat calcium and magnesium; it is fed directly into the tank. There are significant drawbacks: in the P204 washing section, as well as in some of the back-extraction sections, calcium sulfate causes severe blockages, requiring frequent tank cleaning. What is the effectiveness of using a high-concentration cobalt chloride solution to separate magnesium? Why not just use acid washing?
In the P204 back-extraction stage, hydrochloric acid is used, and the calcium sulfate precipitation disappears. Generally, at higher temperatures, a large amount of calcium sulfate crystals are formed at the inlet of the extraction aqueous phase, and it is only possible to remove them
The method for removing magnesium is simple, but caution is needed when it comes to removing calcium
This post was last edited by leilaohu on 2012-6-27 22:18. If there is no extraction system, is ammonium fluoride the only option? If it is in a nitric acid system, is fluoride still the only option? Especially for concentrations around 1 g/L (it’s a pity that calcium/magnium oxalate cannot be used). Fluorine is always a hassle.
For back-extraction at 204, a hydrochloric acid medium is necessary; otherwise calcium sulfate will precipitate, making it difficult to clean up. This is something normal. Controlling magnesium levels is a major issue – the separation coefficient of 507 determines its effectiveness. Making adjustments may help, but it still isn’t conducive to normal production. We need to carry out preliminary treatment of calcium and magnesium early on, so that controlling their levels won’t affect the quality of the products in the entire production process. When running a business, one can’t neglect one aspect at the expense of another
How to handle the pre-magnesium removal? Is the liquid sodium fluoride precipitate?
If the magnesium content is not high, it can be directly sent for extraction. The type of nickel-cobalt product you are producing also determines the level of control required over calcium and magnesium in the early stages of processing; this needs to be determined based on the final product. For example, when producing nickel salt products, higher requirements are placed on magnesium; higher standards mean that it’s not possible to get a good price for them