Flotation Reagent Combinations, Process Design, and Application Scenarios for White Tungsten Ore

The white tungsten ore flotation process has become the dominant technology for recovering white tungsten ore resources due to its strong adaptability to fine-grained, low-grade, and polymetallic ores. Its core principle lies in exploiting the differences in surface physicochemical properties between white tungsten ore and gangue minerals. Through reagent optimization and process design, these differences in mineral floatability are amplified to achieve efficient concentration and separation of white tungsten ore. After years of development, the white tungsten ore flotation process has evolved into a comprehensive technical system encompassing reagent systems, process models, and specialized technologies, capable of adapting to various types of white tungsten ore resources.

I. Core Principles and Adaptability of White Tungsten Ore Flotation

The fundamental reason white tungsten ore is suitable for flotation lies in the high compatibility between its unique mineral characteristics and the principles of flotation. The chemical composition of wolframite is calcium tungstate. Its surface possesses active sites capable of interacting specifically with certain collectors, forming a stable hydrophobic adsorption layer that provides the foundation for flotation separation. Compared to processes such as gravity separation and magnetic separation, flotation offers higher recovery efficiency for finely disseminated wolframite, making it particularly suitable for low-grade ores with fine grain sizes where individual liberation is difficult to achieve through physical methods.

White wolframite commonly occurs in association with gangue minerals such as fluorite, calcite, and quartz. Among these, calcium-bearing gangue minerals share similar surface properties with white wolframite, presenting a major challenge for flotation separation. By adjusting the pulp environment and optimizing reagent combinations, the flotation process can effectively widen the difference in floatability between white wolframite and gangue minerals. For example, under high-alkalinity conditions, modifiers can alter the surface bonding of minerals, enhancing the binding capacity of scheelite with collectors while simultaneously suppressing the floatability of gangue minerals, thereby creating conditions for efficient separation. Furthermore, the flotation process can flexibly address complex ores containing multiple coexisting metals; through selective flotation, it enables the stepwise recovery of scheelite from other metallic minerals, thereby improving the comprehensive utilization rate of resources.

II. Key Reagent Systems for Scheelite Flotation

The selection and combination of reagents are central to the success of scheelite flotation; different reagents exert synergistic effects during the process to achieve selective mineral separation.

The conditioning agent system primarily includes pH adjusters, inhibitors, and activators. pH adjusters are mainly sodium carbonate and sodium hydroxide, with the combination of sodium carbonate and water glass being the most widely used. Sodium carbonate not only regulates the pulp pH to an optimal range, but the carbonate ions released upon its dissociation also adsorb onto mineral surfaces, altering surface polarity. This enhances the adsorption strength of white tungsten ore toward collectors while simultaneously weakening the binding capacity of gangue minerals such as fluorite toward collectors, thereby widening the floatability gap. Sodium hydroxide, on the other hand, rapidly increases the alkalinity of the pulp and is suitable for adjusting the flotation of specific types of ores. Inhibitors, with water glass as the core component, selectively inhibit gangue minerals such as quartz and silicates. When used in combination with macromolecular organic inhibitors such as charred gum and tannin, they can further enhance the inhibition effect on calcium-containing gangue minerals and improve flotation selectivity. For the flotation of certain complex ores, it is also necessary to add metal salt activators, which alter the surface charge state of scheelite to enhance its reactivity with collectors.

Collectors are the key reagents in scheelite flotation. Currently, the most widely used are oxidized paraffin soap collectors, whose core active ingredient is a sodium carboxylate with a specific carbon chain length. These offer advantages such as good selectivity, wide availability, and low cost. Among these, 731 wax soap is the mainstream product. It exhibits strong selective collection capacity for scheelite and can achieve effective flotation of scheelite at room temperature. However, the solubility of this type of collector is significantly affected by temperature; in low-temperature environments, emulsification is required to ensure uniform dispersion in the pulp and prevent a decline in flotation performance due to uneven agent distribution. To address this issue, modified dry powder collectors have emerged. These offer improved solubility, easier transportation and handling, and the ability to adapt to flotation operations under varying temperature conditions. Additionally, the use of mixed collectors is becoming increasingly widespread. Through the synergistic effects of different types of collectors, the collection efficiency and selectivity for white tungsten ore can be further enhanced, making them particularly suitable for complex and difficult-to-process ores.

III. Major Process Models and Operational Key Points for Scheelite Flotation

Based on ore properties and production requirements, various process models for scheelite flotation have been developed, including high-temperature flotation, ambient-temperature flotation, and special flotation techniques. Each model has its own suitable applications and operational guidelines.

High-temperature flotation (also known as the Petrov process) is the traditional and classic flotation process for white tungsten ore. Its core principle is to achieve efficient separation by exploiting the differences in floatability between white tungsten ore and gangue minerals at specific temperatures. This process is typically conducted at a pulp temperature of 60–80°C, using sodium carbonate and water glass as modifiers and fatty acids as collectors. It is stable and highly adaptable, making it particularly suitable for complex ores containing high levels of calcium-bearing gangue minerals such as fluorite and calcite. High-temperature conditions enhance the effectiveness of reagents and increase the hydrophobicity differences on mineral surfaces; however, they require additional energy consumption and increase production costs, making them suitable for large-scale production scenarios with stringent beneficiation requirements.

Room-temperature flotation does not require heating the pulp and offers advantages such as low energy consumption, controllable costs, and simple operation, making it the most widely used flotation method today. Among these, lime-based room-temperature flotation is the most representative. Its core principle involves the synergistic action of lime, soda ash, and water glass to enhance the suppression of gangue minerals. This method first adjusts the pulp by stirring it with lime, then adds soda ash and water glass to create a specific chemical environment in the pulp. While ensuring high recovery rates, it significantly improves concentrate grade and is particularly suitable for skarn-type white tungsten ore. In addition, the 731 ambient-temperature flotation method is also widely used. Employing 731 oxidized paraffin soap as the collector, in combination with sodium carbonate and water glass, this method enables the production of high-quality white tungsten concentrate from low-grade ore through multi-stage enrichment and scavenging. The key to room-temperature flotation lies in precisely controlling reagent dosage and pulp pH to avoid reduced flotation selectivity caused by imbalanced reagent ratios.

For fine-grained white tungsten ore, hydrophobic agglomeration separation technology has become an important auxiliary flotation method. White tungsten ore is brittle and prone to overgrinding during the grinding process. Due to their large specific surface area and high surface energy, fine-grained minerals tend to agglomerate or adsorb onto the surfaces of gangue minerals, resulting in reduced recovery efficiency. Hydrophobic agglomeration separation technology uses a slurry modifier to fully disperse fine-grained minerals from gangue minerals. A surface activator is then applied to make the surface of white tungsten ore hydrophobic, and a non-polar oil is added as a bridging medium. Under the action of a shear force field, fine-grained white tungsten ore aggregates into clusters, which are subsequently recovered efficiently through conventional flotation. This technology effectively addresses the challenge of recovering fine-grained white tungsten ore and improves overall flotation performance.