Study on valuable metal incorporation in the Fe–Al precipitate during neutralization of LIB leach solution

The role of aluminum concentration and pH in the purification of waste Li-ion battery leach solution was investigated using NaOH and LiOH as neutralization agents ([H2SO4] = 0.313 M, t = 6 h). Solution was prepared from synthetic chemicals to mimic real battery leach solution. Results demonstrate that pH (3.5–5.5) has a significant effect on the precipitation of metals (Fe, Al, Ni, Cu, Co, Mn, and Li), whereas higher temperature (T = 30 and 60 °C) decreases the precipitation pH of metals. Iron and aluminum were both found to precipitate at ca. pH 4 and the presence of aluminum in PLS clearly decreased the separation efficiency of Fe vs. active material metals (Ni, Co, Li). In the absence of dissolved aluminum, Fe precipitated already at pH 3.5 and did not result in the co-precipitation of other metals. Additionally, the Al-free slurry had a superior filtration performance. However, aluminum concentrations of 2 and 4 g/L were found to cause loss of Ni (2–10%), Co (1–2%) and Li (2–10%) to the Fe-Al hydroxide cake at pH 4. The use of LiOH (vs. NaOH) resulted in 50% lower co-precipitation of Ni, Co and Li. Overall, these results demonstrate that hydroxide precipitation can be an effective method to remove iron from battery waste leach solutions at aluminum concentrations of < 2 g/L only. Although the highest level of lithium loss in the cake was found at pH 4, the loss was shown to decrease with increasing pH.

Analyzing changes in a leach solution oxygenation in the process of uranium ore borehole mining

Purpose is to increase uranium content in a PR solution while developing a technique varying oxidation-reduction potential of a leach solution with its oxygenation and identify changes in the oxygenation depending upon sulfuric acid concentration as well as transportation distance of the solution. Methods. A laboratory facility, involving solution tank, pump, Venturi tube, tank to install oxygen analyzer, and a dump tank, has been manufactured under the lab conditions to determine a leach solution oxygenation taking into consideration its delivery rate, sulfuric acid concentration, and temporal preservation of the concentration. Solution flow velocity; the deli-vered solution volume; sulfuric acid concentration; and distance from oxygenation point to a seam changed and varied during the study. Oxygenation was measured with the help of AZ 8403 oximeter; IT-1101 device was used to measure pH value as well as oxidation-reduction potential (ORP). Findings. A technique for a leach solution oxygenation and results of laboratory tests to identify influence of a sulfuric acid as well as transportation distance of a solution on oxygen concentration in the solution have been represented. It has been determined that Venturi tube helps oxygenize a leach solution; in this context, maximum oxygen concentration is achieved if a flow velocity is optimum one. It has been specified that a solution oxygenating depends upon a sulfuric acid concentration decreasing moderately with the increasing distance of the solution transportation. Originality.Following new dependencies have been determined: oxygen concentration in a solution upon a flow velocity and solution volume; and oxygen concentration in a solution upon distance from concentration place and sulfuric acid concentration. Practical implications.A leach solution oxygenation results in the increased oxidation-reduction potential and in the increased content of a useful component in the pregnant solution respectively. The proposed technique is notable for its low capital spending. Moreover, it is integrated easily into the available system being absolutely environmentally friendly.

Acidic heap leaching behavior of uranium from El-Sela area, South Eastern Desert, Egypt

The column percolation technique was used to examine the leachability of uranium from El-Sela uranium mineralization. The agglomeration effect, particle size, flow rates, acid concentration, solid to liquid ratio, and sand agglomeration effect were all studied in the kinetics of uranium leaching. The acidic leach solution causes alteration and thus dissolves the oxides that fill joints and fractures, resulting in a reduction in ore particle size, as well as the swelling of fine particles caused by acid leaching over time. As a result, the focus of this research is on the possibility of increasing the permeability of ore heaps by adding cobblestone. At a height of 3.0 m within the column, the optimal ratio of cobblestone to ore was found to be 1:4, and the irrigation rate was reduced from 0.15 to 0.1L/ m2/min, increasing the uranium dissolution efficiency from 47.5 to 79 percent. Finally, the column leaching efficiency is confirmed by fitting data from an application first-order kinetic law with data collected.

Technological improvement of the scheme unit reception and distribution of solution under conditions of high-pressure nature of groundwater

This paper analyses the experience uranium deposits mine development under conditions of highpressure nature of groundwater proposed technology "pumping wells" and upgrading technological scheme unit receiving and distribution of the solution. The results of experimental study of the use of "pumping wells" in mining deposits of uranium by in-situ leaching mine "Karatau". It is proved that by using the proposed technology and circuits under conditions of the high groundwater pressure reduces the cost of procurement of cables, significantly reduced the cost of acquisition of submersible pumps, savings in the end cap. In practice, one processing unit is equipped with one unit for receiving and distributing the solution, therefore, a leaching solution with the same acidity is supplied to all injection wells. To avoid such cases requires selective supply of different concentrations of acid with the different indicators pH. The modernization of the scheme of the unit for receiving and distributing the solution was carried out by connecting two bypass lines, where one bypass line is designed to transfer the injection wells to the pumping one, and the second one is to transfer the pumping wells to the pumping one. By connecting the two bypass lines, it will be possible to supply a leach solution with a higher acid concentration, selectively to any injection well. As a result, acid consumption will decrease due to its selective supply and pH values in wells will be balanced.

Preliminary Study on Gold Recovery from High Grade E-Waste by Thiourea Leaching and Electrowinning

The present paper is focused on the extraction of gold from high-grade e-waste, i.e., spent electronic connectors and plates, by leaching and electrowinning. These connectors are usually made up of an alloy covered by a layer of gold; sometimes, in some of them, a plastic part is also present. The applied leaching system consisted of an acid solution of diluted sulfuric acid (0.2 mol/L) with thiourea (20 g/L) as a reagent and ferric sulfate (21.8 g/L) as an oxidant. This system was applied on three different high-grade e-waste, namely: (1) Connectors with the partial gold-plated surface (Au concentration—1139 mg/kg); (2) different types of connectors with some of which with completely gold-plated surface (Au concentration—590 mg/kg); and (3) connectors and plates with the completely gold-plated surface (Au concentration—7900 mg/kg). Gold dissolution yields of 52, 94, and 49% were achieved from the first, second, and third samples, respectively. About 95% of Au recovery was achieved after 1.5 h of electrowinning at a current efficiency of only 4.06% and current consumption of 3.02 kWh/kg of Au from the leach solution of the third sample.