Ozone Applications in Mining Industry

Ozone, a powerful and environmentally friendly oxidant, is increasingly utilized in the mining industry to address environmental challenges, enhance process efficiency, and ensure regulatory compliance. From treating wastewater to destroying cyanide and oxidizing heavy metals, ozone offers a sustainable solution for mining operations. At Oxidation Technologies, we provide customized ozone systems tailored to the unique needs of mining facilities, delivering reliable and cost-effective results.

Applications of Ozone in Mining:

- Wastewater Treatment: Mining operations generate wastewater containing contaminants such as ammonia, nitrates, and organic compounds. Ozone effectively oxidizes these pollutants, reducing ammonia levels, breaking down organic matter, and improving water quality for reuse or safe discharge. Its high oxidation potential ensures compliance with stringent environmental regulations.

- Cyanide Destruction: Cyanide is commonly used in gold and silver extraction but poses significant environmental risks. Ozone rapidly oxidizes free and complexed cyanide compounds (e.g., sodium cyanide) into less toxic byproducts like cyanate or carbon dioxide and nitrogen, enabling safe disposal or further treatment.

- Heavy Metal Oxidation: Ozone oxidizes heavy metals such as iron, manganese, and arsenic, converting them into insoluble forms (e.g., ferric hydroxide) that can be easily filtered or precipitated. This process reduces metal concentrations in tailings and wastewater, mitigating environmental contamination.

- Tailings Pond Remediation: Ozone treats tailings pond water by reducing chemical oxygen demand (COD), neutralizing toxic compounds, and controlling microbial growth. This improves water quality, minimizes odors, and supports reclamation efforts for mined land.

- Acid Mine Drainage (AMD) Treatment: Ozone can be used in advanced oxidation processes (AOPs) to treat acid mine drainage by neutralizing acidic water, oxidizing dissolved metals, and reducing sulfate concentrations, thereby preventing environmental damage to surrounding ecosystems.

Benefits of Ozone in Mining:

- Environmental Sustainability: Ozone decomposes into oxygen, leaving no harmful residues, making it an eco-friendly alternative to traditional chemical treatments.

- Regulatory Compliance: Ozone ensures mining operations meet strict environmental standards for wastewater discharge and cyanide management, reducing the risk of fines or operational shutdowns.

- Cost-Effectiveness: By reducing the need for chemical reagents and enabling water reuse, ozone lowers operational costs and enhances process efficiency.

- Versatility: Ozone systems can be integrated into existing mining infrastructure, treating a wide range of contaminants in a single process.

- Safety: On-site ozone generation eliminates the need to store hazardous chemicals, improving worker safety and reducing transportation risks.

Specific Mining Applications for Ozone:

Gold and Silver Mining:

Ozone is used in gold and Silver mining primarily to enhance gold recovery from refractory ores and to manage cyanide in wastewater, offering both economic and environmental benefits. Here’s a concise overview of its applications:

Pretreatment of Refractory Ores:

In refractory gold and Silver ores, where Gold or Silver is locked within sulfide minerals like pyrite or arsenopyrite, ozone acts as a powerful oxidizing agent. It breaks down the mineral matrix, liberating gold for subsequent cyanidation. For instance, pretreating an arsenopyritic-pyritic concentrate with ozone in acidic media (pH 1-2) can increase gold recovery from 9% to 23%-55%, depending on conditions like pH and ozonation time. This process oxidizes sulfides and partially destroys preg-robbing carbonaceous material, which otherwise adsorbs gold during leaching.

Cyanide Destruction and Recycling:

Cyanide is widely used in gold extraction but poses environmental risks. Ozone oxidizes cyanide in tailings and wastewater, converting it to less toxic cyanate, then to bicarbonate and nitrogen, enabling safe discharge or recycling. This process typically reduces free and weak acid-dissociable (WAD) cyanide by 99% with an ozone dose of 2-3 g O₃/g CN WAD, and thiocyanate with 3-4 g O₃/g SCN. This allows tailings to be used directly for backfill without further treatment, reducing costs and improving safety compared to chemical oxidizers like hydrogen peroxide.

Heap Leaching Enhancement:

In heap leaching, particularly in cold climates, ozone ice is used as an oxygen release reagent. It supplies dissolved oxygen to the leaching solution, improving gold extraction efficiency. At 5°C, increasing dissolved oxygen from 8.2 mg/L to 12 mg/L with ozone ice doubled the leaching rate at a cyanide concentration of 60 mg/L, addressing oxygen deficiency in low-grade ore heaps.

Nickel and Cobalt Mining:

Ozone’s application in nickel and Cobalt mining primarily focuses on environmental management and metal recovery, leveraging its strong oxidative properties. While not as widely documented as in gold or silver mining, ozone plays a role in specific processes, particularly in wastewater treatment, metal separation, and remediation. Here’s a detailed look:

Nickel Recovery through Oxidation:

- Ozone is used to recover nickel from dilute sulfate solutions, such as those generated from leaching nickel laterite ores or nickel-bearing sludge. In a semi-batch bubble column reactor, ozone oxidizes nickel (II) to form nickel (II) hydroxide (Ni(OH)₂), which is then further oxidized to β-nickel oxyhydroxide (β-NiOOH). This process requires a minimum pH of around 6.8 to initiate the formation of Ni(OH)₂. The resulting β-NiOOH can be precipitated and recovered, offering a method to extract nickel from low-concentration streams. However, ozone consumption often exceeds the stoichiometric amount due to side reactions with the base added to maintain pH, which can increase operational costs.

Separation of Cobalt from Nickel:

- In mixed nickel-cobalt sulfate solutions, ozone selectively oxidizes cobalt (Co(II)) over nickel (Ni(II)) due to differences in oxidation rates. At pH 2.5–5.0 and 60°C, cobalt oxidizes much faster than nickel, allowing for effective separation. This process is enhanced by vigorous agitation and follows a first-order rate with respect to ozone partial pressure. The ability to separate these metals is critical in nickel mining, as cobalt is often a co-product in nickel ores (e.g., laterites), and selective recovery improves the purity of nickel products for applications like battery production.

Wastewater Treatment and Contaminant Removal:

- Nickel and Colbalt mining, particularly from laterite deposits, generates significant wastewater containing heavy metals, sulfates, and organic residues from hydrometallurgical processes like high-pressure acid leaching (HPAL). Ozone can oxidize these contaminants, converting metals like manganese or iron into less soluble forms (e.g., MnO₂) for removal, and breaking down organic acids used in bioleaching. While specific data for nickel mining wastewater is limited, ozone’s proven ability to remove 99% of cyanide in gold mining with a dose of 2-3 g O₃/g CN suggests it could similarly treat nickel mining effluents, enabling water reuse or safe discharge.

Environmental Remediation:

- Nickel mining, especially in equatorial regions like Indonesia, causes significant environmental damage, including deforestation and biomass carbon emissions, which can be 4 to 500 times higher than previously reported. Ozone can be applied in soil and tailings remediation by oxidizing metal(loid)s and organic pollutants, reducing their bioavailability. For example, in contexts like gold mining, ozone oxidizes arsenic in tailings; a similar approach could mitigate the impact of nickel mining’s tailings, which often contain residual metals and contribute to water pollution—a major ESG concern in the industry.

Copper Mining and Refining:

Leaching Enhancement:

- In copper mining, particularly with low-grade sulfide ores (e.g., chalcopyrite, CuFeS₂), ozone can be used as an oxidant to enhance leaching in hydrometallurgical processes. Ozone oxidizes sulfide minerals, converting CuFeS₂ to Cu²⁺ and Fe³⁺, which can then be leached with sulfuric acid. Studies show ozone-assisted leaching can increase copper recovery by 10-15% compared to traditional methods, especially in bioleaching setups where ozone boosts dissolved oxygen levels.

Wastewater Treatment:

- Copper mining generates wastewater with high levels of copper, iron, and sulfates. Ozone oxidizes these metals into less soluble forms (e.g., Fe²⁺ to Fe³⁺, forming Fe(OH)₃ for removal) and degrades organic residues from flotation reagents. Similar to gold mining, where ozone removes 99% of cyanide (2-3 g O₃/g CN), it can reduce copper mining effluent toxicity, enabling water reuse.

Environmental Note:

- Copper mining also contributes to atmospheric ozone depletion via copper-catalyzed reactions, as noted in studies on stratospheric chemistry. While this is unrelated to ozone use in mining, it underscores the need for careful environmental management.

Zinc Mining and Refining:

Sulfide Oxidation:

- Zinc is often extracted from sulfide ores like sphalerite (ZnS). Ozone can pretreat these ores by oxidizing sulfides to sulfates, improving zinc recovery during leaching. For example, ozone can oxidize ZnS to ZnSO₄, increasing zinc extraction efficiency by 8-12% in acidic leaching conditions (pH 1-2), similar to its role in gold sulfide ores.

Wastewater Treatment:

- Zinc mining wastewater contains zinc, lead, and cadmium. Ozone oxidizes these metals into insoluble forms (e.g., Zn²⁺ to Zn(OH)₂) for removal and breaks down organic flotation agents. In analogous gold mining applications, ozone achieves rapid contaminant removal (10-30 minutes), suggesting similar efficacy for zinc effluents.

Lead Mining and Refining:

Sulfide Pretreatment:

- Lead is primarily extracted from galena (PbS). Ozone can oxidize PbS to PbSO₄, enhancing lead recovery in hydrometallurgical leaching. This process mirrors gold mining’s sulfide oxidation, where ozone boosts recovery by breaking down refractory matrices.

Wastewater Treatment:

- Lead mining produces effluents with high lead and sulfate content. Ozone oxidizes lead (Pb²⁺) to less soluble forms for precipitation and removes organic residues, enabling safe discharge or reuse. In gold mining, ozone removes toxic metals like arsenic (89-100%); a similar approach could mitigate lead’s environmental impact, especially in regions like Missouri, a major lead producer.

Uranium Mining and Refining:

Leaching Enhancement:

- In uranium mining, ozone can be used as an oxidant in acid or alkaline leaching to convert uranium (IV) to uranium (VI), forming soluble uranyl ions (UO₂²⁺). For example, in sulfuric acid leaching of uranium ores, ozone increases dissolved oxygen, enhancing the oxidation of UO₂ to UO₂SO₄, improving recovery by 5-10% compared to traditional oxidants like manganese dioxide.

Radioactive Waste Management:

- Uranium mining generates radioactive tailings with thorium and radium. Ozone can oxidize these elements into less mobile forms (e.g., Th⁴⁺ to Th(OH)₄), aiding containment, though this application is speculative and requires specific conditions (likely acidic pH, as in gold mining).

Wastewater Treatment:

- Ozone treats uranium mining wastewater by oxidizing heavy metals and degrading organic residues, enabling safe discharge. Its rapid action (10-30 minutes) mirrors gold mining cyanide removal.

White Papers and Case Studies:

Below are specific case studies and research showcasing the use of ozone in the mining industry.

Pretreatment with Ozone for Gold and Silver Recovery from Refractory Ores

Abstract

In this work ozonization was studied as pretreatment for two Mexican refractory ores in order to increase the gold and silver extraction. Two methods for contacting ozone with the mineral were studied (indirect and direct). The indirect method did not change the precious metals recoveries for mineral sample A, but increased those of mineral B (from 53 to 88% for gold and from 26 to 78% for silver). The direct pretreatment, only tested in mineral A, did not affect gold and silver recoveries but decreased the extraction time from 40 to 24 hours for maximum metal recovery.

Read the full study here.

Use of Ozone for Gold Extraction from a Highly Refractory Concentrate

Abstract

Precious metals are generally recovered from their ores by cyanide leaching. When the gold or silver are locked up in the mineral matrix, they remain unrecovered and the ore is classified as refractory to cyanidation. Ozonization in acidic media of an arsenopyritic-pyritic highly refractory gold concentrate (110 g Au/t) as a treatment prior to cyanidation was evaluated. While the conventional cyanidation of this concentrate recovers only 9% of the gold, a pretreatment with ozone before the cyanidation increases the gold recovery to 23%. The rest of the gold is in solid solution with the matrix. Even if this increase in gold extraction is not large enough to economically process this specific concentrate, it demonstrates that the gold locked up in pyrite or arsenopyrite could be recovered by ozonating the ore before cyanidation.

Read the full study here.

Ozonation Pretreatment of Gold-Silver Pyritic Minerals

Abstract

The use of ozone for the oxidation of cyanidation wastewater has been studied since the 1950's. In the last 2 decades, the use of ozone to oxidize sulfide ores has been studied. This report presents some of the results obtained concerning the use of ozone in the oxidation of raw ores containing gold and silver as well as the treatment of tails or residues of the cyanidation process. The results show that oxidation treatment with ozone prior to cyanidation may help to optimize this process, mainly through reduction of the consumption of cyanide.

Read the full study here.

Pretreatment of Refractory Gold Minerals by Ozonation Before the Cyanidation Process

Abstract

The pretreatment of gold ores before cyanidation is a challenging problem due to the world’s annual huge waste of refractory gold minerals. Generally, the leaching of gold by cyanidation without any pre-oxidation causes an extraction lower than 90%. In recent decades, a variety of treatment and pretreatment methods have been used to increase the recovery of refractory gold ores. The advantages and disadvantages of different techniques were reviewed in this paper compared with the ozonation. Ozone is used for mineral pretreatment in the form of ozone ice, ozone-saturated water and ozone bubbles. In the first step of this work, the application and necessity of gold pretreatment by ozone before cyanidation were analyzed. In the next part, the mechanisms and kinetics of gold ozonation were studied to elaborate on the details of this pre-oxidation process. The ozonation of refractory minerals can improve gold extraction through direct treatment or indirect oxidation. It minimizes gold entrapping with refractory minerals by creating desired oxidizing conditions for sulphides destruction. Therefore, it is a suitable substitution for conventional pretreatment techniques. The dissolution of sulphides increases with an enhancement in ozone concentration in the carrying gas by increasing the driving force of ozone transfer to the aqueous phase for the reaction. The high efficiency, environmental-friendly, short-term process, easy ozone production, strong oxidizing conditions and low capital costs are the considerable properties of ozonation pretreatment. The kinetics of ozonation of pyrite and arsenopyrite was reported to follow the chemical control in previous works.

Read the full study here.

Nickle-Cobalt Separation by Ozonation

Abstract

A process utilizing ozone for the precipitation of cobalt from nickel sulphate liquors containing ammonium sulphate has been developed.  Best results were obtained using nickel carbonate to maintain solution pH at 5.0 to 5.5.  Work was performed both in column and stirred-tank reactors.  Variables studied included neutralizer type and concentration, NH4+ concentration, temperature, Ni++ and Co++ concentration, per cent Ozone in Oxygen carrier gas, Ozone input rate and agitation.  The over-all rate of cobalt rejection increased sharply with increasing agitation and ozone concentration in the gas phase, reflecting relatively slow transfer of ozone from the gas to the liquid phase.

Read the full study here.

Kinetic Study of Manganese Precipitation of Nickel Laterite Leach Based-solution by Ozone Oxidation

Abstract

The increase in nickel and cobalt consumption encourages the exploration of different resources. Limonite ore exploration is carried out through the hydrometallurgical route. After nickel and cobalt separation, the remaining solution contains manganese to be recovered. The present study aimed at the kinetic modeling of manganese precipitation by ozonation. The experiments were carried out in a 250 mL reactor containing an 8-metals sulfated synthetic solution fed by an ozone-oxygen mixture with a bubble diffusor at 21.6–26.0 mg.L⁻¹.min⁻¹ to a total of 2186 mg.L⁻¹ over 90 min. The effects of oxygen flow rate (0.8–10 L.L⁻¹.min⁻¹) and pH (0.5–1.5) varying the ozone dosages and time were studied. Kinetic modeling was performed using linear, Higbie, and pseudo-homogeneous orders. Results showed that the best oxygen flow rate for MnO₂ was 2.0 L.L⁻¹.min⁻¹ achieving 97% of efficiency after dosing 24.3 mg.L⁻¹.min⁻¹ O₃ or 2186 mg.L⁻¹ (ozone applied) for 90 min at pH 1.5 with a power consumption of 80 W.L⁻¹. The reaction was more selective at pH 0.5 in which the highest manganese precipitation of 55.4% and lower amount of contaminants in the solid phase were obtained. The kinetic model study has demonstrated that manganese precipitation using ozone fitted better on the pseudo-homogeneous model, suggesting that the process is controlled by mass transfer, where the calculated constant rates were 0.035, 0.033, and 0.042 min⁻¹ for the experiments carried out at pH 0.5, 1.0 and 1.5, respectively.

Read the full study here.

Nickle Recovered from Solution by Oxidation Using Ozone

Abstract

A process utilizing ozone for the oxidation/precipitation of nickel from sulfate solutions as a recovery option from dilute streams has been studied using a semi-batch bubble column reactor. The results demonstrated that a minimum pH (≈6.8) was required for the reaction to proceed, evidently because the first step is the formation of nickel (II) hydroxide, which is then oxidized to produce β-NiOOH (nickel oxy hydroxide). The sequence of reactions is proposed. Ozone consumption exceeds stoichiometric, possibly due to side reactions with base added to maintain pH. Some physical characteristics of NiOOH, particle size distribution, morphology, density, and settleability, were determined and compared with Ni(OH)₂.

Read the full study here.

Intensification of Sulfuric Acid Leaching of Copper from Sulfide Concentrates Using Ozone and Irons Ions

Abstract

Studies have been conducted to establish the patterns of sulfuric acid dissolution of metal sulfides in the presence of environmentally friendly oxidizing agents, ozone and iron(III) ions; determine the parameters and modes of intensified extraction of metals into solution; reduce the consumption of oxidizing agents; and develop the least environmentally intense and most cost-effective methods for the extraction of nonferrous metals from sulfide ores, concentrates, and industrial wastes. A copper sulfide concentrate with a grain size of 0.074 mm (90%) and a copper content of 24.5% obtained by the flotation concentration of ore from the Udokan deposit and ozone with a concentration of 80–180 mg/L in a mixture with oxygen are used for the study. The concentrate is fed into a stirred reactor at a rate of 1–5 mL/s. Patterns are studied within the sulfuric acid concentration range 20–100 g/L and a Fe(III) ion concentration of 7.8–29.2 g/L at a solid phase to liquid phase ratio 1.1–1.5 at a temperature of 18–60°C. It has been established that the use of Fe(III) ions and ozone can significantly intensify the recovery of copper from sulfides in sulfuric acid solutions. The extraction of copper from sulfides increases in proportion to the 2.4-fold increase in the concentration of Fe(III) from 7.8 to 29.25 g/L. Ozone effectively oxidizes Fe(II) and regenerates the oxidizing agent, Fe(III) ions. With an increase in the temperature and iron concentration, the consumption of ozone for oxidation increases; namely, 0.22 mol of O₃ is consumed per 1 mol of Fe, which is higher than a theoretical value of 0.17. An increase in the rate of the ozone-assisted extraction of copper from sulfides is achieved by increasing the temperature from 20 to 50°C (by 1.4 times), the concentration of ozone from 85 to 180 mg/L (3 times), the feed rate of the ozone–oxygen gas mixture from 1 to 5 mL/s (2.7 times at 20°C and 3.9 times at 50°C), and by the addition of Fe(III) ions by ~1.5 times at 50°C and [Fe(III)] = 10 g/L. The largest oxidizing activity in the sulfuric acid solution is provided by ozone decomposition products at a temperature of 50°C when the solubility of ozone decreases. The ozone utilization coefficient and specific ozone consumption rate for extracted copper decrease with an increase in the feed rate of the ozone–oxygen gas mixture from 1 to 5 mL/s by 1.42 times at 20°C and by 1.16 times at 50°C and increase with an increase in the temperature and concentration of Fe(III) due to the rapid decomposition of ozone and its unproductive use for the oxidation of iron.

Read the full study here.

Removal of Rare-Scattered Metal Impurities in Zinc Sulfate Solution by Ozone Oxidation

Abstract

There are abundant strategic rare-scattered metal resources in lead and zinc deposits in China, especially zinc resources in Yunnan province, which are associated with indium (In), selenium (Se), tellurium (Te), etc. Small amounts of these rare-scattered metal ions are dissolved into zinc acidic leaching solutions, and are difficult to remove by conventional zinc powder replacement. They are enriched in the ZnSO4 solution, which causes serious problems to the zinc electrowinning process such as hydrogen generation, zinc re-dissolution, plate burning, low current efficiency, etc. So, they need to be deeply purified from ZnSO4 solution. This article used ozone, a strong oxidizing agent, to make oxidative precipitation of the impurities from ZnSO4 solution. The effects of reaction temperature, ozone flow rate, and residence time on In, Se, and Te removal together with the associated Mn removal and Zn loss were investigated. The ozonation reaction kinetics was evaluated by plotting the negative logarithm of the metals in solution concentration as a function of reaction time. One precipitate prepared at optimized conditions was characterized by XRD, EDS, and SEM to identify the chemical compounds and morphology.

Read the full study here.

Direct Sulfuric Acid Leaching of Zinc Sulfide Concentrate Using Ozone as Oxidant Under Atmospheric Pressure

Abstract

The use of ozone as an oxidant for the direct leaching of zinc sulfide (sphalerite) concentrate in sulfuric acid medium under atmospheric pressure was explored. The influence of acid concentration, feed gas injection rate, particle size distribution, stirring speed, temperature and slurry density on zinc extraction efficiency was examined. The experimental results showed that the leaching efficiency depends on all of these operating parameters except for stirring speed. It was found that essentially complete dissolution of zinc from the concentrate with the present method can be achieved in only about seven hours under the conditions of sulfuric acid concentration of 2 mol/L, particle size smaller than 74 µm, slurry density of 50 g/L, stirring speed of 420 rpm and feed gas injection rate of 1 L/min at ambient temperature. The experimental results suggest that the dissolution reactions produce independent elemental sulfur that is readily floated and can be easily separated rather than forming a layer on the surface of the reacted particle, as usually observed in a system with ferric-sulfate as oxidizing agent. It was therefore determined that the dissolved ozone play a key role in improving the rate of zinc dissolution from the concentrate. Analysis of the leaching kinetics indicate that the leaching rate follows the shrinking particle model, and the overall dissolution rate of zinc is controlled by a surface reaction.

Read the full study here.

Efficiency of Ozone Application for Extraction of Metals from Mineral Raw Materials

Abstract

The results of studies on the use of ozone for the extraction of nonferrous, rare, and noble metals from ores, enrichment concentrates, and technogenic raw materials, identified from world scientific publications and in patent literature since the beginning of the 20th century, are summarized. Ozone is a strong oxidizing agent, the oxidation potential of which is 1.5 times higher than the potential of chlorine in an acidic environment. With the participation of ozone, even resistant metals and minerals are dissolved. The use of ozone for the extraction of metals from mineral raw materials is not accompanied by contamination of processed products and the formation of hazardous waste. A significant number of studies have been presented on the use of ozone to dissolve gold and other noble metals in mineral acids, showing an increase in the extraction of metals into solution. Cyanide and thiocarbamide leaching of gold from mineral raw materials by replacing oxygen with ozone have been studied. The results of vat and heap leaching of nonferrous and noble metals using ozone obtained by irradiation of air or oxygen with ultraviolet light, in particular, using photoelectrochemical treatment, are presented, on the basis of which new technologies are patented. An assessment of the effectiveness of ozone application for flotation enrichment of mineral raw materials, purification and detoxification of solutions and solid products of metallurgical processing, regeneration of other oxidizing agents, and extraction of metals from technological solutions is given. The results of studies on the use of ozone for vat leaching of metals from refractory sulfide ores and sulfide enrichment concentrates in acid solution, as well as the study of the kinetics of oxidation with the participation of ozone of sulfide minerals of copper, iron, zinc, and molybdenum, are summarized. The results of using a combination of ozone with other oxidizing agents—hydrogen peroxide and iron(III) ions—for the extraction of metals from sulfide mineral raw materials in a sulfuric acid solution are presented and analyzed. According to the results of most studies, it can be concluded that the use of ozone is effective for the extraction of metals from mineral raw materials: the technological parameters of the processes increase (extraction of metals into solution, selectivity of the extraction of metals from complex raw materials) and the duration of processing decreases.

Read the full study here.

Enhanced Oxidative Sulfuric Acid Leaching of Granite-type Uranium Ore by Oxygen Nanobubbles

Authors: Ting Li, Guangyue, Xiaohui Liu, Jing Sun, Qian Lu, Zhao Cui

Abstract

Developing eco-friendly and highly efficient uranium-enhanced leaching technologies is crucial for ensuring the reliable supply of uranium resources. This study integrates nanobubble (NB) technology into the acid leaching process of granite-type uranium ore by employing oxygen NBs as an effective, clean oxidant to enhance uranium leaching. The feasibility of using oxygen NBs was first validated theoretically, and subsequent batch experiments were conducted to investigate the enhanced leaching kinetics and mechanism. The results demonstrate that oxygen NB-enhanced leaching follows a shrinking core model dominated by product layer diffusion, with an Arrhenius activation energy of 8.37 kJ/mol. Under optimal conditions (15 g/L H₂SO₄, 180 rpm, 5 % pulp density, and 30 °C), oxygen NBs increased uranium leaching efficiency by 8.20 % compared to conventional sulfuric acid leaching. Three key mechanisms contribute to this enhancement: (i) efficient oxidation of U(IV) to U(VI) via continuous dissolution of molecular oxygen and generation of hydroxyl radicals; (ii) expansion of leaching pathways through high-energy microarea effects that further disrupt the ore structure; and (iii) reduction of leaching inhibition by preventing sulfate precipitate deposition on mineral surfaces. These findings underscore the potential of oxygen NB-enhanced oxidative leaching for sustainable, cost-effective uranium extraction, warranting pilot-scale studies for industrial application.

Read the full study here.

Oxidative Leaching of Sandstone Uranium Ore Assisted by Ozone Mirco-Nano Bubbles

Authors: Rui Zhang, Wei Hou, Eming Hu, Hongquiang Wang

Abstract

The oxidation efficiency and leaching rate of ozone micro-nano bubbles (OMNBs) on UO2 and sandstone uranium ore were explored and evaluated through a batch oxidation experiment of sandstone uranium ore and a continuous flow oxidation experiment of UO2. OMNBs can accelerate the rate of oxidative leaching. Oxidation mainly relies on ozone oxidation. Oxidation of sandstone uranium ore by OMNBs was feasible, and OMNBs may solve current problems encountered in production practice. The continuous flow experiment verified the feasibility of the large-scale experiment and provided a new method for CO2 + O2 ISL of uranium under normal pressure in the future.

Read the full study here.