I would like to ask about the appropriate methods for nickel smelting

3.1 Acid leaching and ammonia leaching: Acid leaching is the most widely used method among the techniques for leaching solid waste; the specific acid to be used for leaching depends on the properties of the solid waste. For the treatment of industrial waste from electroplating, casting, smelting, and other processes, sulfuric acid is one of the most effective leaching agents; it is widely used due to its low cost, low volatility, and resistance to decomposition. Silva et al. conducted experimental studies on the recovery of nickel and zinc from electroplating sludge through sulfuric acid leaching, using diisooctyl phosphate as an extractant. Studies by Vegli et al. show that sulfuric acid can achieve an leaching rate of 95%–100% for copper and nickel, and during the electrolytic recovery process, the recovery rates for these two metals are also as high as 94%–99%. Other acidic extractants (such as acidic thiourea) can also be used to leach heavy metals from electroplating sludge. Paula et al. used inexpensive industrial hydrochloric acid to leach chromium from electroplating sludge. For this purpose, 5 mL of industrial hydrochloric acid (with a purity of 25.8% and a mass concentration of 1.13 g/mL) was added to approximately 1 g of the prepared sample, which was then shaken in a shaker at 150 r/min for 30 minutes; the leaching rate of chromium reached 97.6%. Although the technology of extracting metals using ammonia leaching has a certain history, compared to acid leaching, there are relatively few research reports on the use of ammonia leaching for treating electroplating sludge, and most of these reports come from China. The ammonia leaching method generally uses an ammonia solution as the leaching agent, owing to its moderate alkalinity, ease of use, and reusability. By adopting the process of ammonia complexation group leaching – ammonia evaporation – hydrolysis of the residue followed by sulfuric acid leaching – solvent extraction – and crystallization of metal salts, it is possible to recover the vast majority of valuable metals from electroplating sludge; the overall recovery rates for copper, zinc, nickel, chromium, and iron are greater than 93%, 91%, 88%, 98%, and 99% respectively. To address the difficulty in selecting extractants suitable for separating copper from ammonia leachate systems, Zhu Wanpeng and his colleagues developed an extractant named N510, which can effectively recover Cu2+ from the ammonia leachate of electroplating sludge in a kerosene-H2SO4 system, with a recovery rate as high as 99%. Research by Wang Haodong and others on the recovery of nickel from electroplating sludge using the ammonia leaching method shows that nickel-containing sludge is subjected to oxidative roasting to produce roasted ore. This roasted ore is then leached using ammonia water with a 7% mass fraction of NH3 and a 5%–7% mass fraction of CO2; this process results in a solution containing Ni(NH3)4CO3. The solution is subsequently evaporated to convert Ni(NH3)4CO3 into NiCO3·3Ni(OH)2, which can then be calcined at 800°C to yield commercial nickel oxide powder. When treating electroplating sludge through acid leaching or ammonia leaching, the overall recovery rate of valuable metals and the ease with which they can be separated from other impurities are primarily determined by the leaching rate of these valuable metals during the leaching process, as well as by the selectivity of the leaching solution regarding valuable metals and impurities. The main advantage of the acid leaching method is its good efficiency in leaching valuable metals such as copper, zinc, and nickel, but it has low selectivity for impurities, especially those like chromium and iron. On the other hand, the ammonia leaching method exhibits higher selectivity for impurities such as chromium and iron, but it results in lower leaching rates for metals like copper, zinc, and nickel. 3.2 Biological leaching The main principle of biological leaching is to utilize the acid-producing ability of chemolithoautotrophic Acidithiobacillus bacteria to dissolve insoluble heavy metals from the solid phase into the liquid phase, where they become soluble metal ions. These ions can then be recovered from the leachate using appropriate methods. The mechanism involved is complex, including microbial growth and metabolism, adsorption, and transformation processes. Based on the literature available to date, there are relatively few studies on the use of biological leaching methods for treating electroplating sludge. The reason for this is that the high levels of heavy metals in electroplating sludge have a toxic effect on microorganisms, which limits the application of this technology in this field. Therefore, how to reduce the toxic effects of the high levels of heavy metals in electroplating sludge on microorganisms, and how to cultivate strains with strong adaptability and high efficiency in waste treatment, remain major challenges for the bioleaching method; yet they are also key to realizing the application of this technology in this field. 3.3 Smelting method and roasting-leaching method: The smelting method is used to treat electroplating sludge primarily with the aim of recovering copper and nickel from it. The smelting method uses coal and coke as fuels and reducing agents, with auxiliary materials including iron ore, copper ore, limestone, etc. When sludge rich in copper is melted, the furnace temperature is above 1300°C, and the copper that is melted is called matte; when sludge rich in nickel is melted, the furnace temperature is above 1455°C, and the nickel that is melted is called crude nickel. Billet copper and crude nickel can be directly separated and recovered by electrolysis. Slag is generally used as a raw material for construction materials. The principle of the calcination-leaching method is to first use high-temperature calcination to pre-treat the impurities in sludge, and then use agents such as acid and water to extract the valuable metals from the calcined products. Using pyrite waste as the acidification material, it was mixed with electroplating sludge and then roasted. The roasted product was subsequently leached and separated using deionized water at room temperature, resulting in recovery rates of 60% for zinc, 43% for nickel, and 50% for copper.

The metals in the electroplating sludge are leached using sulfuric acid; copper in the leachate is separated by extraction using the M5640-kerosene-sulfuric acid system, while nickel in the remaining extract is separated by precipitation with sodium carbonate.

Given the current low prices, it’s best to store them for now; the wet processing method mentioned above is not economical! This post was last edited by limingshuguang on 2009-3-25 19:57.]

Which product determines the processing route to be followed? For instance, in the case of ball nickel production, zinc powder is used to replace copper in 507 concentrated nickel, followed by back-extraction to produce nickel sulfate, which is then sent to the ball nickel processing plant

We have process technologies for treating electroplating sludge via wet or thermal methods; unit: China Ruilin, Class A, 0791—86757957