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Article

Synergistic Leaching of Low-Grade Tungsten–Molybdenum Ore via a Novel KMnO4-Na2CO3-NaHCO3 Composite System Guided by Process Mineralogy

1
Key Laboratory for Ecological Metallurgy of Multimetallic Mineral (Ministry of Education), Northeastern University, Shenyang 110819, China
2
School of Metallurgy, Northeastern University, Shenyang 110819, China
3
Ningxia Institute of Science and Technology, Shizuishan 753000, China
*
Author to whom correspondence should be addressed.
Minerals 2025, 15(7), 712; https://doi.org/10.3390/min15070712
Submission received: 29 May 2025 / Revised: 28 June 2025 / Accepted: 2 July 2025 / Published: 3 July 2025
(This article belongs to the Section Mineral Processing and Extractive Metallurgy)

Abstract

The mineral processing of a low-grade tungsten-molybdenum ore (LGTMO) was investigated to assess the potential of recovering molybdenum (Mo) and tungsten (W). Techniques such as Polarizing Microscope (PM), Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS), Mineral Liberation Analysis (MLA), and Advanced Mineral Identification and Characterization System (AMICS) were employed. The recoverable metals in the ore are Mo (0.158% ± 0.03%) and W (0.076% ± 0.02%). Mo exists in two forms: 63.30% as molybdenite and 36.7% as powellite (CaMoxW1−xO4). W is present as 75.26% scheelite and 24.74% powellite. The complete dissociation rates of molybdenite and scheelite-powellite are 27.14% and 88.87%, respectively. Particles of scheelite-powellite with a diameter less than 10 µm account for 34.61%, while molybdenite particles with a diameter below 10 µm make up 72.73%. Scheelite-powellite is mainly associated with olivine and dolomite, while molybdenite is mainly associated with pyroxene, calcite, and hornblende. Based on the process mineralogy, the mineralogical factors influencing the flotation recovery of molybdenite and scheelite-powellite were analyzed. Finally, a complete hydrometallurgical leaching test was carried out. The optimal experimental conditions are as follows: liquid-solid ratio of 6 mL/g, KMnO4 concentration of 0.015 mol/L, Na2CO3 concentration of 0.12 mol/L, NaHCO3 concentration of 0.024 mol/L, leaching time of 4 h, and leaching temperature of 85 °C. Under these conditions, the leaching efficiencies of Mo and W reach 79.23% and 41.41%, respectively. This study presents a novel approach for the recovery of refractory W and Mo resources in LGTMO while simultaneously providing a theoretical basis for the high-efficiency utilization of these resources.

1. Introduction

Tungsten (W) and molybdenum (Mo) are extremely important strategic rare metals, which are widely used in fields such as iron and steel, the chemical industry, electrical and electronic technology, medicine and agriculture, and aerospace and aviation [1,2,3]. The top five countries in Mo production are China, Chile, Peru, the United States, and Mexico, with production volumes of 110,000 tons, 46,000 tons, 37,000 tons, 34,000 tons, and 14,000 tons, respectively. The top five countries in W reserves are China, Australia, Russia, Vietnam, and Spain, with reserves of 2,300,000 tons, 570,000 tons, 400,000 tons, 74,000 tons, and 66,000 tons, respectively [4].
However, due to the continuous exploitation and consumption of W and Mo resources, the easily mined and easily processed tungsten-molybdenum ores are diminishing year by year [5]. In the future, low-grade tungsten-molybdenum ore (LGTMO) will become the main resource for development and utilization. How to achieve the efficient development and utilization of LGTMO with complex compositions and difficult beneficiation is becoming increasingly crucial [6].
Skarn-type tungsten-molybdenum deposits, as an important type of tungsten-molybdenum ore deposits, are typically associated with granite intrusions in specific geological settings [7]. Their genesis is related to magmatic hydrothermal activities and involves complex physicochemical processes. Process mineralogy has now been widely recognized as a necessary condition for ore characterization, project design, production process optimization, and other aspects. The processability of valuable minerals in ores can be diagnosed through process mineralogical studies on ores, providing a basis for the optimization of mineral processing plant processes [8,9]. In recent years, mineral detection technologies have been used to reduce risks in new circuit design and to detect and correct inefficiencies in flotation and leaching circuits. Therefore, its application can provide theoretical support for the selection of recovery processes for valuable metals in ores [10].
At present, the main hydrometallurgical methods for molybdenite include the nitric acid oxidation method, the sodium chlorite oxidation decomposition method, the electrochemical oxidation method, and the bioleaching method. The nitric acid oxidation method has high requirements for equipment performance, generates harmful gases, and has harsh reaction conditions [11]. The electrochemical oxidation decomposition method can accurately control the leaching process and reduce the use of chemical reagents but has low current efficiency and needs to optimize the electrode materials [12]. The bioleaching process is environmentally friendly and low in cost, but the growth and metabolic conditions of microorganisms are harsh and the leaching cycle is long [13]. The sodium chlorite acidic oxidation leaching method has strong oxidation activity under acidic conditions but has high requirements for the control of acidity and alkalinity and generates harmful gases [14]. The decomposition processes for scheelite mainly include the soda high-pressure leaching method, sodium hydroxide high-pressure leaching method, and sulfur-phosphoric mixed acid leaching method. The soda high-pressure leaching method has a wide application range for various ores but requires high-temperature and high-pressure conditions and consumes a large amount of soda [15]. The sodium hydroxide high-pressure leaching method can simultaneously process both wolframite and scheelite but features high NaOH consumption and strict equipment requirements [16]. Sulfur-phosphoric mixed acid leaching method shows remarkable leaching efficiency for scheelite, but there are technical difficulties in the complete treatment of phosphoric acid in the leaching solution [17].
Potassium permanganate (KMnO4) is a commonly used oxidizing agent, boasting advantages such as strong oxidizing ability, mild reaction conditions, relatively clean reaction products, low cost, and ease of storage and use [18]. Especially under alkaline conditions, it can still maintain strong oxidizing properties, making it highly suitable for the oxidation treatment of molybdenite in LGTMO. Sodium carbonate (Na2CO3) is a common reagent used for the leaching of scheelite and powellite [19]. During the leaching process, it exhibits good selectivity and mild reaction conditions. It not only has excellent environmentally friendly performance and low cost but also facilitates subsequent purification and separation operations.
In this study, the process mineralogy of LGTMO was investigated by means of the Mineral Liberation Analyzer (MLA) [20,21], Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS), and other detection means. And an in-depth analysis was carried out in terms of the chemical composition, mineral composition, chemical phase composition, dissociation of main minerals, size distribution of main minerals, mineral association, and mineralogical factors affecting beneficiation. Consequently, an all-wet process is adopted to extract W and Mo from LGTMO. KMnO4 is used as the oxidant for molybdenite, and Na2CO3 and sodium bicarbonate (NaHCO3) are used as the leaching agents for scheelite and powellite. By coupling the oxidation of molybdenite with the leaching process of scheelite-powellite, a new solution is provided for the efficient extraction of W and Mo from refractory LGTMO.

2. Materials and Methods

2.1. Ore Sample and Reagents

The raw material was sourced from an open storage yard in the western region of Henan Province, China. The grinding process was conducted using a laboratory-scale damp mill (MSK-SFM-1-3l, Hefei Kejing Materials Technology Co., Ltd., Hefei, China). The particle size distribution of the ground material was analyzed using a laser particle size analyzer (BT-9300H, Bettersize Instruments Ltd., Dandong, China), as shown in Figure 1. Additionally, raw ore samples with dimensions ranging from 5 to 10 cm were selected for the preparation of polished sections and thin sections, which were processed by Beijing Sun-Moon Stone Technology Co., Beijing, China.
All chemicals were of analytical reagent grade unless otherwise specified. KMnO4 was obtained from Shuangshuang Chemical Co., Ltd. (Yantai, China). Na2CO3 was purchased from Yuanye Biotechnology (Shanghai, China). NaHCO3 was supplied by Tianjin Kemiou Chemical Reagent Co., Ltd. (Tianjin, China).

2.2. Characterization Methods

The elemental composition of the sample was characterized via X-Ray Fluorescence (XRF) (ZSX100e, Rigaku Corporation, Tokyo, Japan; RSD < 0.5%). The W and Mo in the ore were simultaneously determined by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) (Optima 8300DV, PE, MA, USA; RSD ≤ 1%). The sample was first mounted in a 30 mm diameter epoxy resin block. The surface of the sample was cut, polished, and coated with carbon and then submitted to MLA for analysis. MLA analyzes the sample using the area analysis method. The BSE image of the sample was first acquired by SEM. The domains of each mineral particle were then determined based on the gray-level variation in the BSE image. For each particle domain, a point array was placed on it, and at each point an X-ray spectrum was acquired and its mineral properties were determined. Finally, a mineral map of the measured sample surface was generated along with the corresponding mineral statistics, such as mineral liberation, association, and particle size distribution [22].

2.3. Leaching Experiments

All experiments were conducted in a 250 mL three-necked flask, which was immersed in a high-precision constant-temperature water bath (W2-100SP, SENCO, Shanghai, China) to guarantee a constant temperature. In each leaching experiment, 50 g of LGTMO was added to the three-necked flask, and then the mixed solution of KMnO4, Na2CO3, and NaHCO3 was added into the flask to reach a set temperature. After that, the reaction system was continuously agitated by a magnetic stirrer at 300 rpm to ensure homogeneous mixing. A reflux condensation system was employed to maintain a constant solution volume throughout the leaching process. After the leaching time, the mixture was separated with a filter flask, and changes in the W and Mo content in the solution were determined. The residues were washed and dried for further characterization. The leaching efficiency ( η ) of Mo or W can be calculated using the following Formula (1).
η = C · V m · w × 100 %
m: The mass of LGTMO before the reaction (g); w: Mass fractions of Mo or W in LGTMO before the reaction (%); C: Concentration of Mo or W in the leaching solution (g/L); V: The volume of the leaching solution (L).

3. Results and Discussion

3.1. Chemical Composition of LGTMO

The XRF results are shown in Table 1. The main elements in LGTMO are Ca, Si, and Mg, with mass fractions reaching 36.93%, 32.82%, and 19.84%, respectively, which are the primary components of Ca-Mg silicate and carbonate minerals. Additionally, LGTMO contains valuable Mo and W, with quantitative mass fractions of 0.158% ± 0.03% and 0.076% ± 0.02%, respectively.

3.2. Mineral Composition of LGTMO

In general, the grinding quality of an ore is highly dependent on its mineral phase composition. Therefore, the mineralogical composition of the LGTMO was comprehensively analyzed using MLA [23]. Further analysis of the qualitative mineral composition of LGTMO by AMICS is presented in Table 2 [24,25,26].
Molybdenum-bearing minerals are molybdenite and powellite; tungsten-bearing minerals are scheelite and powellite; a zinc-bearing mineral is sphalerite; sulfur-bearing minerals are pyrite and chalcopyrite; a copper-bearing mineral is chalcopyrite; iron-bearing minerals are magnetite; and there are also small amounts of manganosite in LGTMO. Non-metallic minerals are mainly pyroxene, olivine, dolomite, and calcite, followed by hornblende, quartz, rankinite, fluorite, mica, a small amount of feldspar, actinolite, garnet, and occasionally rutile, etc.

3.3. Chemical Phase Analysis of LGTMO

The chemical phase analysis of Mo and W was carried out, and the results are shown in Table 3, which shows that 63.30% of the Mo exists in the form of molybdenite, and the oxidation rate of the molybdenite is 36.7%; 75.26% of the W in the ore exists in the form of scheelite, and 24.74% of the W exists in the form of powellite.

3.4. Mineral Occurrence of Main Minerals

In order to prove the above inference and further elucidate the surface morphology of minerals, Polarizing Microscope (PM) and SEM-EDS were employed to observe the surface morphology of different minerals.

3.4.1. Analysis of Polarizing Microscope

LGTMO was made into a light film and thin section, and then the existence state of its main minerals was observed from Figure 2 [27,28,29]. Under the PM, molybdenite occurs in the veins, exhibiting vein-like and massive structures. Scheelite–powellite fills the vein voids with a fine-grained structure. Magnetite exists within the gangue minerals, presenting an authomorphic or semi-authomorphic structure. Pyrite shows a lead-grey metallic luster and fills the vein voids in vein-like interwoven or filamentous structures. while chalcopyrite fills the gangue minerals with a fine-grained structure.

3.4.2. Occurrence of Molybdenite

Molybdenite is the main beneficial mineral in LGTMO. Figure 3a,c show SEM images of different particles of molybdenite, and Figure 3b,d show EDS images of different points of molybdenite (a and b, c and d correspond to each other). BSE images of molybdenite are shown in Figure 3e,f.
Molybdenite is embedded in the form of sheet-like aggregates (Figure 3a,c). The embedded particle size of molybdenite is relatively fine (Figure 3a), and local enrichment is more common. Molybdenite is commonly found in more regular forms such as elongated, flaky, and scaly ones, and occasionally in irregular granular, crumpled, and chrysocolla-like aggregates. From Figure 3c, it can be seen that molybdenite is in the form of strips with a length of 30 µm, and the surface is relatively smooth without wrapping and adherence. Figure 3b and Figure 3d are the energy spectrum diagrams corresponding to Figure 3a and Figure 3c, respectively. The results show that the contents of Mo and S in different molybdenite particles are uneven, with an average Mo content of 61.77% and an S content of 38.73%. From the BSE images in Figure 3e,f, it can be seen that the chemical elements are Mo and S. Based on these elements, the mineral is determined to be molybdenite.

3.4.3. Occurrence of Scheelite-Powellite

Figure 4a,c show SEM images of different particles of scheelite-powellite, and Figure 4b,d show EDS images of different points of powellite (a and b, c and d correspond to each other). BSE images of powellite are shown in Figure 4e–g.
The results of the SEM-EDS analysis of scheelite-powellite are shown in Figure 4. Scheelite-powellite are the main tungsten-bearing minerals in LGTMO and also one of the target minerals for W recovery. In Figure 4a,b, scheelite-powellite is mainly irregularly embedded, presenting an angular shape with smooth edges and dispersed particles; their favorable particle size ranges from 5 to 20 µm. By comparing Figure 4c and Figure 4d, it can be seen that the content fluctuations of calcium and Mo in the ore are relatively small, while there are relatively large fluctuations in the content of Mo and oxygen, which is directly related to the oxidation degree of molybdenite. The higher the oxidation degree of molybdenite, the higher the oxygen content in the corresponding ore area. Moreover, from the energy spectrum analysis in Figure 4e–g, the elements of Ca, Mo, and W in the ore do not completely overlap. There are some areas where only Mo exists without calcium and W. By combining the analysis of the mineral phases in the ore, it can be determined that this area is composed of molybdenite. Therefore, it can be determined that the main formation process of powellite is as follows: the oxidized molybdenite undergoes isomorphism with the scheelite in the ore to form powellite, and the formed powellite is closely associated with molybdenite.

3.5. Properties and Embedding Characteristics of the Main Minerals

3.5.1. Dissociation of Main Minerals

The dissociation characteristics of scheelite-powellite and molybdenite were shown in Table 4.
The results in Table 4 show that 66.32% of scheelite-powellite dissociates more than 60% and 88.87% of molybdenite dissociates more than 60%. It can be concluded that both molybdenite and scheelite-powellite possess a relatively high dissociation degree.

3.5.2. Size Distribution of Main Minerals

The distribution of major mineral particle sizes is shown in Table 5.
For beneficiation, minerals with a particle size less than 10 µm are easy to sludge and difficult to recover. The particle size of scheelite-powellite in LGTMO is mainly distributed between 10 and 23 µm, and the minerals with a particle size less than 10 µm account for 34.61%. Meanwhile, the minerals with a particle size less than 10 µm account for 72.73% of the samples of molybdenite. Based on these particle size distribution characteristics and the general rules of beneficiation, the MLA test results show that scheelite-powellite is more difficult to beneficiate due to the relatively higher proportion of fine particles, and molybdenite is the most difficult to beneficiate as a large portion of it has a very fine particle size that is prone to sludging and hard to recover effectively.

3.5.3. Association of Main Minerals

The association of the minerals was determined using AMICS. Then, the statistical analysis of the embedded area ratio was carried out for the particles containing the target minerals to determine the association between the target minerals and the other minerals. The statistical results are presented in Table 6.
The results show that the LGTMO has a monomer dissociation degree of 74.56% and is mainly associated with olivine, scheelite, pyroxene, dolomite, calcite, hornblende, fluorite, and other minerals. Molybdenite has a monomer dissociation degree of 92.78% and is mainly associated with pyroxene, calcite, hornblende, olivine, mica, dolomite, fluorite, and other minerals. In combination with the schematic diagram of the mineral composition of the AMICS, it can be found that the dominant associated gangue minerals in LGTMO are calcite, olivine, dolomite, and pyroxene. Given the complexity of the ore composition, it is extremely difficult to beneficiate it.

3.5.4. Gangue Minerals

The ore was fabricated into different light sheets as well as thin slices, and the microscopic morphology of the gangue minerals was directly observed through Figure 5.
The ore contains a significant amount of pyroxene, calcite, olivine, and mica. Calcite is present in the ore as both authigenic grains (Figure 5a) and veins (Figure 5b). Pyroxene and olivine are closely intergrown in the ore (Figure 5c). And quartz is present as authigenic fine grains (Figure 5d). Furthermore, calcite, quartz, and mica show intergradation (Figure 5e), with mica filling in along quartz gaps (Figure 5f). This microscopic intergrowth relationship of minerals is consistent with the results of the AMICS.

3.6. Mineralogical Factors Affecting Beneficiation

3.6.1. Mineralogical Factors Affecting Molybdenite Recovery

The Mo minerals in the ore are characterized by low-grade, complex mineral composition, a high oxidation degree of molybdenite, and heterogeneous distribution. Molybdenite is the main mineral for Mo recovery. Only 63.30% of Mo is distributed in molybdenite, and the oxidation rate is 36.7%. If molybdenite is recovered through flotation, its theoretical recovery rate is only 63.3% [30]. Molybdenite has a high proportion of −10 µm difficult-to-select grains, accounting for about 72.73%, and requires fine grinding to dissociate the monomer. However, fine grinding is easy to cause sludging, and molybdenite and gangue minerals in the ore are closely coexisting, which will bring certain difficulties to the sorting of the ore. Therefore, in the flotation process, fine-grained molybdenite is easy to enter the tailing with mud, which in turn affects the recovery of Mo [31,32].
Molybdenite is closely associated with pyroxene, calcite, hornblende, olivine, mica, and dolomite. And the poor floatability of the gangue minerals leads to the fact that the associated particles of molybdenite and gangue minerals cannot float but remain in the flotation tailings, which affects the recovery of molybdenite. Part of the Mo replaces the W in the scheelite lattice in a homogeneous state to form powellite. The Mo in powellite will enter the molybdenite flotation tailing, which will result in lower Mo recovery. About 0.5% of other sulfide ores (pyrite, chalcopyrite, etc.) in the ore, which have good floatability, will continue to be enriched in the flotation process and affect the quality of Mo concentrates if they are not suppressed during the flotation of molybdenite.

3.6.2. Mineralogical Factors Affecting Scheelite-Powellite Recovery

Scheelite-powellite is the main target for W recovery. The ore, which contains 28.71% of carbonate minerals (calcite and dolomite) and 2.28% of fluorite, causes difficulties in the flotation of scheelite-powellite. This is because the similar flotation properties of powellite, scheelite, calcite, fluorite, and other calcium-bearing gangue minerals lead to a large number of carbonate minerals and fluorite entering the tungsten concentrate [33].
The embedded particle size of W minerals in the ore is fine, with 34.61% of W minerals having a particle size of less than 10 µm, and it is more difficult for this part of fine-grained and microscopic W minerals to be completely dissociated in the milling process, and even if they are dissociated into a single state, it is more difficult to be recovered due to the fine particle size.

3.6.3. Other Influencing Factors

The content of pyroxene in the ore is 23.51%. Pyroxene is a chain silicate mineral with low hardness. It is easy to be muddied, coalesce heterogeneously with molybdenite, and form a mud cover on the surface of molybdenite. It not only affects the flotation of molybdenite but also floats up to the concentrate with molybdenite, affecting the grade of the concentrate [34,35]. The content of olivine in the ore is 19.12%. Olivine is an island silicate. Olivine is very hydrophobic by nature and tends to float up with the molybdenite, affecting the concentrate grade [36].
Based on the research of process mineralogy, it is rather difficult to recover molybdenite and scheelite-powellite by flotation. Therefore, adopting the all-wet process is a better choice.

3.7. Leaching Experiments of Tungsten and Molybdenum

3.7.1. Dissolution Performance of LGTMO

A study was conducted on the influencing factors of the leaching performance of LGTMO, with the aim of finding the optimal process parameters for the leaching of W and Mo. The parameters and conditions of all single-factor experiments are shown in Table 7. The experimental results are shown in Figure 6.
The liquid-solid ratio significantly influences ion diffusion and mass transfer during leaching, thereby exerting a critical impact on leaching efficiency [37]. As shown in Figure 6a, increasing the liquid-solid ratio from 2 mL/g to 10 mL/g increased the leaching efficiency of Mo from 50.76% to 65.50%, while that of W rose from 18.69% to 36.67%. When the liquid-solid ratio increases from 2 mL/g to 6 mL/g, the effective concentration of the leaching agent in the liquid phase is sufficient to maintain mineral dissolution. The increase in liquid volume expands the solid-liquid contact interface and shortens the ion diffusion path, thus improving the leaching efficiencies of Mo and W. However, when the liquid-solid ratio exceeds 6 mL/g, the excessive liquid phase leads to dilution of the leaching agent concentration, weakening the reaction driving force and causing a decrease in leaching efficiency. Maximum Mo (65.74%) and W (32.59%) leaching efficiencies were achieved at an optimal liquid-solid ratio of 6 mL/g.
Figure 6b demonstrates that increasing Na2CO3 concentration from 0 to 0.15 mol/L enhanced Mo leaching from 31.59% to 70.23%, with W increasing from 16.17% to 34.20%.
When the concentration of Na2CO3 is 0 mol/L, the main leaching reagent for scheelite-powellite is absent. In this case, Mo and W in the solution mainly originate from the oxidation of molybdenite by KMnO4, along with minor decomposition of scheelite-powellite. The leaching efficiencies of Mo and W are relatively low, at 31.59% and 16.17%, respectively. As the concentration of Na2CO3 increases, the leaching efficiencies of Mo and W gradually increase. This improvement is attributed to CO32− decomposition of scheelite-powellite, releasing MoO42− and WO42− into solution [38]. Optimal performance was achieved at 0.12 mol/L Na2CO3, with Mo and W leaching efficiencies reaching 70.23% and 33.73%, respectively.
Increasing NaHCO3 concentration from 0 to 0.030 mol/L (Figure 6c) boosted Mo leaching efficiency from 40.87% to 70.39%, while the W leaching efficiency decreased from 48.13% to 33.50%. The HCO3-CO32− buffer system stabilized the pH of the solution, promoting scheelite-powellite decomposition [39]. Concurrently, reduced alkalinity enhanced KMnO4’s oxidizing capacity, increasing molybdenite oxidation. However, because the solubility product of MnWO4 (KSP = 3.2 × 10−13) is smaller than that of CaWO4 (KSP = 8.7 × 10−9), the Mn2+ generated by the reduction of KMnO4 caused partial precipitation of WO42− in the solution, thereby reducing the leaching efficiency of W [40]. At the optimal NaHCO3 concentration of 0.024 mol/L, Mo and W leaching efficiencies reached 70.39% and 33.73%, respectively.
The leaching efficiency of Mo was more significantly affected by KMnO4 concentration than that of W (Figure 6d). Increasing the concentration of KMnO4 from 0 to 0.025 mol/L caused Mo leaching efficiency to range from 30.27% to 70.28%, while the leaching efficiency of W decreased from 62.2% to 33.67%. When the addition amount of KMnO4 is 0, the leaching efficiency of Mo and W are 30.27% and 62.2%, respectively. In the ore, only scheelite–powellite is leached by carbonate. Although this can avoid the precipitation of MnWO4, molybdenite cannot be oxidized. As a strong oxidant, KMnO4 oxidizes molybdenite to MoO42− and SO42−, promoting mineral decomposition and enhancing Mo dissolution [41]. However, an elevated concentration of KMnO4 increased Mn2+ concentration, leading to the coprecipitation of WO42− as MnWO4 in the leaching residues [40]. The higher the concentration of KMnO4, the higher the concentration of Mn2+ generated, the more WO42− precipitated in the solution, and the lower the leaching efficiency of W. Optimal performance occurred at 0.015 mol/L KMnO4, achieving 71.35% Mo and 38.31% W leaching.
As the leaching time increased, the leaching efficiencies of both Mo and W initially increased and then plateaued. Figure 6e shows that the leaching efficiency of Mo increased from 59.57% to 76.07% and that the leaching efficiency of W ranged from 32.50% to 42.48%. At the beginning of the reaction, the high concentration of the leaching agent led to a rapid leaching efficiency. However, as the agent was consumed, its concentration in the solution decreased, causing the leaching efficiency to slow down and gradually reach a stable state. When the leaching time reached 4 h, the leaching efficiencies of Mo and W were close to their maximum values, which were 74.45% and 40.29%, respectively.
As the temperature rose, the leaching efficiencies of both Mo and W increased initially and then leveled off. Figure 6f shows that the leaching efficiency of Mo increased from 61.25% to 80.65%, and the leaching efficiency of W increased from 16.55% to 42.59%. An increase in temperature raises the average kinetic energy of the reactant molecules. This, in turn, increases the number of activated molecules per unit volume and the probability of effective collisions [42]. This is beneficial for enhancing the reaction rate and the leaching efficiency. When the leaching temperature was increased from 85 °C to 90 °C, the leaching efficiency of Mo increased from 79.23% to 80.65%, and the leaching efficiency of W increased from 41.41% to 42.59%. The improvement in the leaching efficiencies was not significant. At 85 °C, the leaching efficiencies of Mo and W were 79.23% and 41.41%, respectively.
Based on the single-factor experiments, the optimal conditions for the leaching process were determined as follows: liquid-solid ratio of 6 mL/g, KMnO4 concentration of 0.015 mol/L, Na2CO3 concentration of 0.12 mol/L, NaHCO3 concentration of 0.024 mol/L, leaching time of 4 h, and leaching temperature of 85 °C. Under these conditions, the leaching efficiency of Mo was 79.23%, and the leaching efficiency of W was 41.41%.

3.7.2. SEM-EDS Analysis of the Leaching Residue

To further study the leaching behavior of W and Mo and conduct phase analysis during the leaching process of LGTMO, SEM-EDS analysis was conducted on the LGTMO and the leaching residue. Figure 7 shows the SEM-EDS of the leaching residue.
As can be seen from Figure 7a, point 1, point 2, and point 3 are tentatively identified as magnetite, dolomite, and pyroxene, respectively. Meanwhile, neither molybdenite nor scheelite–powellite is observed, which indicates that the molybdenite has been completely oxidized and the scheelite–powellite has been completely decomposed by Na2CO3 and NaHCO3. In the map analysis presented in Figure 7b, trace amounts of Mn and W are detectable. The W is predominantly derived from a minor quantity of MnWO4. In contrast, Mo is scarcely detectable in these map analyses. This observation clearly indicates that the leaching of Mo has occurred relatively comprehensively.

4. Conclusions

The main metal elements in LGTMO are Mo and W with grades of 0.158% ± 0.03% and 0.076% ± 0.02%, respectively; the oxidation rate of molybdenite in the ore is 36.7%. Moreover, 75.26% of the W in the ore exists in the form of scheelite and 24.74% of the W in the form of powellite; 66.32% of the mass of scheelite-powellite dissociates more than 60%, and 88.87% of molybdenite dissociates more than 60%. Molybdenite and scheelite–powellite exhibit relatively high dissociation degrees, which are beneficial for subsequent separation processes. The particle size of scheelite–powellite in LGTMO mainly ranges between 10 and 23 µm, and particles with a size less than 10 µm account for 34.61%. Meanwhile, molybdenite particles with a size less than 10 µm account for 72.73% of the total molybdenite samples. Powellite has a monomer dissociation degree of 74.56%, which is mainly associated with olivine, scheelite, pyroxene, dolomite, calcite, hornblende, fluorite, and other minerals. Molybdenite has a monomer dissociation degree of 92.78%, which is mainly associated with pyroxene, calcite, hornblende, olivine, mica, dolomite, fluorite, and other minerals.
The optimal experimental conditions for the leaching of LGTMO are as follows: liquid–solid ratio of 6 mL/g, KMnO4 concentration of 0.015 mol/L, Na2CO3 concentration of 0.12 mol/L, NaHCO3 concentration of 0.024 mol/L, leaching time of 4 h, and leaching temperature of 85 °C. Under these conditions, the leaching efficiencies of Mo and W are 79.23% and 41.41%, respectively. Through SEM-EDS analysis of the leaching residue, it is found that the formation of MnWO4 is the main reason for the low leaching efficiency of W.
This study provides a novel and effective approach for the extraction of W and Mo from LGTMO, which has potential applications in the mining and metallurgical industries to improve the utilization efficiency of Mo and W resources.

Author Contributions

Conceptualization, J.K., H.Z. and H.Y.; data curation, J.K., H.Z., X.W., B.X. and H.Y.; formal analysis, J.K.; funding acquisition, H.Y.; investigation, J.K.; methodology, J.K., L.T., Q.Z., H.Z., X.W. and H.Y.; project administration, J.K., L.T., Q.Z., H.Z., B.X. and H.Y.; resources, B.X. and H.Y.; supervision, H.Y.; validation, J.K.; visualization, J.K.; writing—original draft, J.K. and X.W.; writing—review and editing, L.T. and Q.Z. All authors have read and agreed to the published version of the manuscript.

Funding

This research program was financially supported by the Major projects for the “Revealed Top” Science and Technology of Liaoning Province (2022JH1/10400024), and the Natural Science Foundation of Ningxia (2024AAC03340).

Data Availability Statement

Data supporting the findings of this study will be made available from the corresponding author upon reasonable request.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Qi, M.; Peng, W.; Wang, W.; Cao, Y.; Zhang, L.; Huang, Y. A Novel Molybdenite Depressant for Efficient Selective Flotation Separation of Chalcopyrite and Molybdenite. Int. J. Min. Sci. Technol. 2024, 34, 1179–1196. [Google Scholar] [CrossRef]
  2. Wang, H. Efficient Dissolution of Tungstic Acid by Isopolytungstate Solution Based on the Polymerization Theory of Tungsten. Hydrometallurgy 2022, 209, 105835. [Google Scholar] [CrossRef]
  3. Xiao, L.; Ji, L.; Yin, C.; Chen, A.; Chen, X.; Liu, X.; Li, J.; He, L.; Sun, F.; Zhao, Z. Tungsten Extraction from Scheelite Hydrochloric Acid Decomposition Residue by Hydrogen Peroxide. Miner. Eng. 2022, 179, 107461. [Google Scholar] [CrossRef]
  4. USGS. Mineral Commodity Summaries 2024; USGS: Reston, VA, USA, 2024. Available online: https://pubs.usgs.gov/publication/mcs2024 (accessed on 31 January 2024).
  5. Pan, W.; Li, S.; Zhu, Y.; Gao, L.; Ma, Z.; Cao, Y.; Chen, X.; Du, S. Application of a Novel Auxiliary Collector for Molybdenite Fines Recovery in Sustainable Froth Flotation Production: Combining DFT Calculations and Experiments. Colloids Surf. A 2025, 704, 135570. [Google Scholar] [CrossRef]
  6. Li, H.; Han, Y.; Jin, J.; Gao, P.; Zhou, Z. Process Mineralogy Approach to Optimize Curing-Leaching in Vanadium-Bearing Stone Coal Processing Plants. Int. J. Min. Sci. Technol. 2023, 33, 123–131. [Google Scholar] [CrossRef]
  7. Li, N.; Yang, F.; Zhang, Z.; Yang, C. Geochemistry and Chronology of the Biotite Granite in the Xiaobaishitou W-(Mo) Deposit, Eastern Tianshan, China: Petrogenesis and Tectonic Implications. Ore Geol. Rev. 2019, 107, 999–1019. [Google Scholar] [CrossRef]
  8. Ji, Q.; Li, G.; Zhu, X.; Gao, T.; Qin, G.; Xu, C.; Cai, M.; Lu, Z.; Chen, Y.; Zhang, J.; et al. Process Mineralogy Automatic Detection System in Research of a Gold Polymetallic Mine. J. Phys. Conf. Ser. 2023, 2428, 12009. [Google Scholar] [CrossRef]
  9. Liu, J.; Xing, Z.; Liu, J.; Ding, X.; Xue, X. Evaluation of the Potential of Recovering Various Valuable Elements from a Vanadiferous Titanomagnetite Tailing Based on Chemical and Process Mineralogical Characterization. Environ. Sci. Pollut. Res. 2023, 30, 83991–84001. [Google Scholar] [CrossRef]
  10. Yi, G.; Macha, E.; Van Dyke, J.; Ed Macha, R.; McKay, T.; Free, M.L. Recent Progress on Research of Molybdenite Flotation: A Review. Adv. Colloid Interface Sci. 2021, 295, 102466. [Google Scholar] [CrossRef]
  11. Khoshnevisan, A.; Yoozbashizadeh, H. Application of Artificial Neural Networks to Predict Pressure Oxidative Leaching of Molybdenite Concentrate in Nitric Acid Media. Miner. Process. Extr. Metall. Rev. 2012, 33, 292–299. [Google Scholar] [CrossRef]
  12. Chung, K.W.; Yoon, H.-S.; Kim, C.-J.; Jeon, H.-S. Selective Leaching of Molybdenum from Bulk Concentrate by Electro-Oxidation. Metals 2021, 11, 1904. [Google Scholar] [CrossRef]
  13. Yu, J.; Yang, H.-Y.; Tong, L.-L.; Zhu, J. Intensified Bioleaching of Low-Grade Molybdenite Concentrate by Ferrous Sulfate and Pyrite. Rare Met 2015, 34, 207–214. [Google Scholar] [CrossRef]
  14. Ganbari Arbat, A.; Asghari Fesaghandis, E.; Taghizadeh Tabrizi, A.; Aghajani, H. Comparison of the Effect of NaClO3 and H2O2 on the Molybdenum Leaching from Molybdenite Concentrate. Trans. Indian Inst. Met. 2020, 73, 2355–2360. [Google Scholar] [CrossRef]
  15. Zhao, Z.; Li, J.; Wang, S.; Li, H.; Liu, M.; Sun, P.; Li, Y. Extracting Tungsten from Scheelite Concentrate with Caustic Soda by Autoclaving Process. Hydrometallurgy 2011, 108, 152–156. [Google Scholar] [CrossRef]
  16. Zhao, Z.; Liang, Y.; Liu, X.; Chen, A.; Li, H. Sodium Hydroxide Digestion of Scheelite by Reactive Extrusion. Int. J. Refract. Met. Hard Mater 2011, 29, 739–742. [Google Scholar] [CrossRef]
  17. Li, J.; Ma, Z.; Liu, X.; Chen, X.; Zhao, Z. Sustainable and Efficient Recovery of Tungsten from Wolframite in a Sulfuric Acid and Phosphoric Acid Mixed System. ACS Sustain. Chem. Eng. 2020, 8, 13583–13592. [Google Scholar] [CrossRef]
  18. Oraby, E.A.; Eksteen, J.J.; O’Connor, G.M. Gold Leaching from Oxide Ores in Alkaline Glycine Solutions in the Presence of Permanganate. Hydrometallurgy 2020, 198, 105527. [Google Scholar] [CrossRef]
  19. Cheng, T.C.; Soriano, C.; Jamieson, H.; Falck, H. Leaching Kinetics of Tungsten in Scheelite Tailings in Sodium Carbonate Solutions at Low Temperatures (25–75 °C). Can. Metall. Q. 2024, 63, 1484–1492. [Google Scholar] [CrossRef]
  20. Xu, C.; Chi, R.; Zhang, Y.; Zhong, C.; Ruan, Y.; Lyu, R.; Zhou, F. Process Mineralogy of Bayan Obo Rare Earth Ore by MLA. Physicochem. Probl. Miner. Process. 2020, 56, 737–745. [Google Scholar] [CrossRef]
  21. Xu, C.; Zhong, C.; Lyu, R.; Ruan, Y.; Zhang, Z.; Chi, R. Process Mineralogy of Weishan Rare Earth Ore by MLA. J. Rare Earths 2019, 37, 334–338. [Google Scholar] [CrossRef]
  22. Gao, H.; Hu, Y.; Yang, H.; Meng, Q.; Tong, L.; Zhang, Q. Process Mineralogy and Leaching Toxicity of High-Sulfur Residue from Oxygen Pressure Zinc Leaching. JOM 2023, 75, 1068–1078. [Google Scholar] [CrossRef]
  23. Hu, W.; Tian, K.; Zhang, Z.; Guo, J.; Liu, X.; Yu, H.; Wang, H. Flotation and Tailing Discarding of Copper Cobalt Sulfide Ores Based on the Process Mineralogy Characteristics. Minerals 2021, 11, 1078. [Google Scholar] [CrossRef]
  24. Hou, X.; Yang, Z.; Wang, Z. Occurrence State and Distribution Regularity of Key Metal Element Niobium in Bayan Obo Deposit, China. JOM 2023, 75, 2753–2762. [Google Scholar] [CrossRef]
  25. Huang, M.; Shao, Y.; Li, X.; Liu, D.; Ouyang, J.; Zhou, L.; Liu, Z. Process Mineralogical Study of U/Th Occurrence States and the Carrier Minerals in Refractory Tantalum Slag. Miner. Eng. 2024, 205, 108496. [Google Scholar] [CrossRef]
  26. Yang, H.; Shi, X.; Luo, C.; Wu, W.; Li, Y.; He, Y.; Zhong, K.; Wu, J. Mineral Composition of Prospective Section of Wufeng-Longmaxi Shale in Luzhou Shale Play, Sichuan Basin. Minerals 2021, 12, 20. [Google Scholar] [CrossRef]
  27. Dabek, P.; Chudy, K.; Nowak, I.; Zimroz, R. Superpixel-Based Grain Segmentation in Sandstone Thin-Section. Minerals 2023, 13, 219. [Google Scholar] [CrossRef]
  28. Tang, H.; Wang, H.; Wang, L.; Cao, C.; Nie, Y.; Liu, S. An Improved Mineral Image Recognition Method Based on Deep Learning. JOM 2023, 75, 2590–2602. [Google Scholar] [CrossRef]
  29. Wang, X.; Liu, N.; Nan, J.; Wang, X.; Ren, D. Characteristics and Genetic Mechanism of Chang Eight Low Permeability and Tight Reservoir of Triassic Yanchang Formation in Central-East Ordos Basin. Front. Phys. 2022, 9, 801264. [Google Scholar] [CrossRef]
  30. Han, Z.; Levett, A.; Edraki, M.; Jones, M.W.M.; Howard, D.; Southam, G. Microbially Influenced Tungsten Mobilization and Formation of Secondary Minerals in Wolframite Tailings. J. Hazard. Mater. 2023, 445, 130508. [Google Scholar] [CrossRef]
  31. Ge, B.; Liu, S.; Nie, Q.; Li, Q.; Zhu, C. Applying One-Stage Grinding and Flotation to Improving Copper Recovery of a Fine-Grained Cu-Mo Sulphide Ore. Sep. Sci. Technol. 2013, 48, 1900–1905. [Google Scholar] [CrossRef]
  32. Zhang, W.; Chen, J.; Xu, S.; Jin, X.; Sun, W.; Gao, Z. Advanced Collector-Free Flotation of Typical Sulfide Minerals Using a Novel Heterocyclic Depressant. Miner. Eng. 2023, 199, 108120. [Google Scholar] [CrossRef]
  33. Dai, L.; Liu, J.; Li, D.; Hao, J.; Gao, H. A New Insight on a Novel Auxiliary Collector 4-MBA Synergize with BHA to Enhance Flotation of Scheelite. Sep. Purif. Technol. 2024, 346, 127412. [Google Scholar] [CrossRef]
  34. Yang, Y.; Xu, L.; Deng, J.; Liu, S. Influence of Particle Size on Flotation Separation of Ilmenite, Olivine, and Pyroxene. Physicochem. Probl. Miner. Process. 2021, 57, 106–117. [Google Scholar] [CrossRef]
  35. Yu, P.; Ding, Z.; Miao, Y.; Yuan, J.; Yu, A.; Tang, Y.; Wen, S.; Bai, S. Synergism Mechanism of the Combined NaOL-SDBS Collector at Solid-Liquid Interface and Its Response to Flotation Separation of Ilmenite from Pyroxene. Surf. Interfaces 2024, 51, 104760. [Google Scholar] [CrossRef]
  36. Fang, S.; Xu, L.; Wu, H.; Shu, K.; Wang, Z.; Xu, Y. Influence of Aluminum–Sodium Silicate on Olivine Flotation with Sodium Oleate. Miner. Eng. 2019, 143, 106008. [Google Scholar] [CrossRef]
  37. Yin, C.; Ji, L.; Chen, X.; Liu, X.; Zhao, Z. Efficient Leaching of Scheelite in Sulfuric Acid and Hydrogen Peroxide Solution. Hydrometallurgy 2020, 192, 105292. [Google Scholar] [CrossRef]
  38. Đorđević, N.; Mihajlović, S.; Vlahović, M.; Šajić, J.L.; Martinović, S. Thermal Analysis and Phase Changes of Mechanochemically Activated Sodium Carbonate. Thermochim. Acta 2022, 708, 179139. [Google Scholar] [CrossRef]
  39. Hesami, R.; Ahmadi, A.; Hosseini, M.R.; Torabi, M. Effect of Mechanical Activation on the Hypochlorite Leaching of Sarcheshmeh Molybdenite Concentrate. Sep. Sci. Technol. 2022, 57, 1966–1977. [Google Scholar] [CrossRef]
  40. Cai, Y.; Ma, L.; Xi, X.; Nie, Z.; Nie, Z. Separation of Tungsten and Molybdenum Using Selective Precipitation with Manganese Sulfate Assisted by Cetyltrimethyl Ammonium Bromide (CTAB). Hydrometallurgy 2020, 198, 105494. [Google Scholar] [CrossRef]
  41. Saidi, M.; Kadkhodayan, H. Toxic Heavy Metal Removal from Sulfide Ores Using Potassium Permanganate: Process Development and Waste Management. J. Environ. Manag. 2020, 276, 111354. [Google Scholar] [CrossRef]
  42. Yang, L.; Zhang, X.; Cao, C.; Huang, X.; Wan, L. Sustainable and Efficient Leaching of Tungsten from Scheelite Using the Mixture of Ammonium Phosphate, Ammonia and Calcium Fluoride. Hydrometallurgy 2022, 210, 105846. [Google Scholar] [CrossRef]
Figure 1. Particle size distribution of LGMTO.
Figure 1. Particle size distribution of LGMTO.
Minerals 15 00712 g001
Figure 2. Main metallic minerals in LGTMO ((a) Molybdenite; (b) Scheelite; (c) Powellite; (d) Magnetite; (e) Pyrite; (f) Chalcopyrite).
Figure 2. Main metallic minerals in LGTMO ((a) Molybdenite; (b) Scheelite; (c) Powellite; (d) Magnetite; (e) Pyrite; (f) Chalcopyrite).
Minerals 15 00712 g002
Figure 3. SEM-EDS and BSE images of molybdenite ((a,c) SEM of Molybdenite; (e,f): EDS of Mo and S; (b,d) BSE of Molybdenite).
Figure 3. SEM-EDS and BSE images of molybdenite ((a,c) SEM of Molybdenite; (e,f): EDS of Mo and S; (b,d) BSE of Molybdenite).
Minerals 15 00712 g003
Figure 4. SEM-EDS and BSE images of scheelite-powellite ((a,b): SEM of scheelite-powellite; (c,d) BSE of scheelite-powellite; (eg): EDS of Ca, W and Mo).
Figure 4. SEM-EDS and BSE images of scheelite-powellite ((a,b): SEM of scheelite-powellite; (c,d) BSE of scheelite-powellite; (eg): EDS of Ca, W and Mo).
Minerals 15 00712 g004
Figure 5. Microscopic view of non-metallic minerals. ((a) Authigenic calcite; (b) Vein calcite; (c) Pyroxene-olivine intergrowth; (d) Granular quartz; (e) Intergrown quartz, calcite and mica; (f) Intergrown quartz and mica).
Figure 5. Microscopic view of non-metallic minerals. ((a) Authigenic calcite; (b) Vein calcite; (c) Pyroxene-olivine intergrowth; (d) Granular quartz; (e) Intergrown quartz, calcite and mica; (f) Intergrown quartz and mica).
Minerals 15 00712 g005
Figure 6. Influence of process parameters on the LGTMO leaching ((a) Liquid–solid ratio; (b) Na2CO3 concentration; (c) NaHCO3 concentration; (d) KMnO4 concentration; (e) Leaching time; (f) Temperature).
Figure 6. Influence of process parameters on the LGTMO leaching ((a) Liquid–solid ratio; (b) Na2CO3 concentration; (c) NaHCO3 concentration; (d) KMnO4 concentration; (e) Leaching time; (f) Temperature).
Minerals 15 00712 g006
Figure 7. SEM-EDS of the leaching residue ((a) ×1500; (b) ×500).
Figure 7. SEM-EDS of the leaching residue ((a) ×1500; (b) ×500).
Minerals 15 00712 g007
Table 1. The multi-element XRF qualitative analysis of LGTMO (mass fraction %).
Table 1. The multi-element XRF qualitative analysis of LGTMO (mass fraction %).
ElementCaOSiO2MgOFe2O3Al2O3MnOK2O
Content36.93532.82219.845.9751.4211.1230.744
ElementMoO3WO3ZnOTiO2P2O5CuOPbO
Content0.2040.0970.0910.0630.0340.0250.024
Table 2. Mineral composition and relative content of LGTMO.
Table 2. Mineral composition and relative content of LGTMO.
MineralMolecularContent/%MineralMolecularContent/%
MagnetiteFe3O43.29 ± 0.8Olivine(Mg, Fe)2SiO419.11 ± 5.82
PyriteFeS20.30 ± 0.25DolomiteCaMg(CO3)216.63 ± 1.02
PowelliteCaMoxW1−xO40.1 ± 0.1CalciteCaCO312.09 ± 5.82
ManganositeMnO0.07 ± 0.04HornblendeCa2Mg5Si8O22(OH)25.88 ± 5.77
ScheeliteCaWO40.08 ± 0.07QuartzSi8O25.40 ± 1.53
MolybdeniteMoS20.04 ± 0.03RankiniteCa3Si2O73.47 ± 2.86
ChalcopyriteCuFeS20.03 ± 0.03FluoriteCaF22.28 ± 2.04
SphaleriteZnS0.02 ± 0.02MicaKAl2(AlSi3O10)(OH)22.19 ± 0.15
PyroxeneCaSi2O623.51 ± 9.48FeldsparK(AlSi3O8)0.81 ± 0.09
Table 3. Chemical phase analysis of LGTMO (%).
Table 3. Chemical phase analysis of LGTMO (%).
ElementElemental PhaseContentDistribution Ratio
MoMolybdenite0.10063.30
Powellite0.05836.70
WScheelite0.07375.26
Powellite0.05824.74
Table 4. Dissociation of main minerals.
Table 4. Dissociation of main minerals.
Degree of
Dissociation
Scheelite-PowelliteMolybdenite
Distribution
Rate (%)
Cumulative
Distribution Rate (%)
Distribution
Rate (%)
Cumulative
Distribution Rate (%)
0%1.70100.001.30100.00
0% < x ≤ 20%12.0198.301.1198.70
20% < x ≤ 40%0.5586.292.7897.59
40% < x ≤ 60%19.4285.745.9494.81
60% < x ≤ 80%0.4566.320.0088.87
80% < x < 100%38.7365.870.0088.87
100%27.1427.1488.8788.87
Table 5. Size distribution of major minerals.
Table 5. Size distribution of major minerals.
Particle Size Fraction (µm)Scheelite–PowelliteMolybdenite
Distribution
Rate (%)
Cumulative
Distribution Rate (%)
Distribution
Rate (%)
Cumulative
Distribution Rate (%)
48 µm ≤ Particle size < 73 um0.000.000.000.00
23 µm ≤ Particle size < 48 um0.000.000.000.00
18 µm ≤ Particle size < 23 um26.5826.580.000.00
13 µm ≤ Particle size < 18 um16.4443.0227.2727.27
10 µm ≤ Particle size < 13 um22.3765.390.000.00
Particle size < 10 um34.61100.0072.73100.00
Table 6. Association of main minerals (area ratio/%).
Table 6. Association of main minerals (area ratio/%).
SampleMonomerAssociation
Powellite74.56OlivineScheelitePyroxeneDolomiteCalciteHornblendeFluoriteOther
9.923.663.461.120.740.810.155.58
Molybdenite92.78PyroxeneCalciteHornblendeOlivineMicaDolomiteFluorite
2.080.990.600.530.360.230.05
Table 7. Experimental conditions for LGTMO leaching.
Table 7. Experimental conditions for LGTMO leaching.
No.Liquid–Solid Ratio
(mL/g)
Na2CO3
(mol/L)
NaHCO3
(mol/L)
KMnO4
(mol/L)
Time
(h)
Temperature
(°C)
12, 4, 6, 8, 100.090.0240.025380
260, 0.03, 0.06, 0.09, 0.12, 0.150.0240.025380
360.120, 0.006, 0.012,
0.018, 0.024, 0.030
0.025380
460.120.0240, 0.005, 0.010, 0.015, 0.020, 0.025380
560.120.0240.0152, 3, 4, 5, 680
660.120.0240.015470, 75, 80,
85, 90
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Kang, J.; Tong, L.; Zhang, Q.; Zhao, H.; Wang, X.; Xiong, B.; Yang, H. Synergistic Leaching of Low-Grade Tungsten–Molybdenum Ore via a Novel KMnO4-Na2CO3-NaHCO3 Composite System Guided by Process Mineralogy. Minerals 2025, 15, 712. https://doi.org/10.3390/min15070712

AMA Style

Kang J, Tong L, Zhang Q, Zhao H, Wang X, Xiong B, Yang H. Synergistic Leaching of Low-Grade Tungsten–Molybdenum Ore via a Novel KMnO4-Na2CO3-NaHCO3 Composite System Guided by Process Mineralogy. Minerals. 2025; 15(7):712. https://doi.org/10.3390/min15070712

Chicago/Turabian Style

Kang, Jian, Linlin Tong, Qin Zhang, Han Zhao, Xinyao Wang, Bin Xiong, and Hongying Yang. 2025. "Synergistic Leaching of Low-Grade Tungsten–Molybdenum Ore via a Novel KMnO4-Na2CO3-NaHCO3 Composite System Guided by Process Mineralogy" Minerals 15, no. 7: 712. https://doi.org/10.3390/min15070712

APA Style

Kang, J., Tong, L., Zhang, Q., Zhao, H., Wang, X., Xiong, B., & Yang, H. (2025). Synergistic Leaching of Low-Grade Tungsten–Molybdenum Ore via a Novel KMnO4-Na2CO3-NaHCO3 Composite System Guided by Process Mineralogy. Minerals, 15(7), 712. https://doi.org/10.3390/min15070712

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