Gold ore flotation technology mainly utilizes the difference in the hydrophobicity of the mineral surface and the affinity with water, and then separates the gold ore from the ore through bubbles. In the flotation process, it is usually necessary to add flotation agents such as collectors, frothers, and inhibitors to adjust the physical and chemical properties of the slurry and promote the separation of gold ore and impurity minerals. Gold ore flotation technology can process various types of gold ores, especially low-grade ores or complex and difficult-to-select ores. The following content will give you a detailed introduction to gold flotation technology, flotation agents and other aspects, to help the application of gold flotation technology.
Gold ore flotation process
01
Preparation work before gold flotation
The gold ore is crushed and ground to a particle size suitable for flotation. Jaw crushers and ball mills are usually used to ensure that the minerals are fully dissociated. The gold ore after grinding is screened or graded to control the ore particle size. If the gold ore particle size is too coarse or too fine, it will affect the subsequent flotation effect. Generally, the ideal particle size is between 50 and 150 μm.
02
Gold flotation process
The gold flotation process can be divided into three stages: roughing, concentrating and scavenging. Roughing is the initial flotation of the pulp to quickly recover most of the gold minerals. Concentrating is the further flotation of the roughing product to remove impurities and improve the quality of the concentrate. Concentrating generally requires multiple times to meet the mineral processing standards. Scavenging is the recovery of roughing tailings. Because there are still a few gold minerals left in the tailings, scavenging can avoid the loss of these gold minerals and improve the comprehensive recovery rate of gold.
Key operating factors of gold flotation
The operation during the flotation process will directly affect the beneficiation effect and concentrate grade, including: pH value, pulp concentration, gas flow rate and reagent addition amount. These factors will affect each other, so they need to be optimized and adjusted according to the ore characteristics and process requirements to ensure the efficient recovery of gold ore.
1. pH value: directly affects the chemical properties of the mineral surface and the effect of the reagent. Gold flotation is generally carried out under weak alkaline conditions. During the process, lime or sodium carbonate needs to be added to adjust the pulp pH value.
2. Pulp concentration: Ensuring that the pulp concentration is within a reasonable range is conducive to the stable formation of the foam layer and improves the flotation efficiency.
3. Gas flow rate: Adjusting the air flow rate can control the size and number of bubbles generated. The appropriate gas flow rate can ensure that the gold ore is fully attached to the bubbles and avoid the interference of excess bubbles.
4. Reagent addition amount: When flotating gold ore, it is necessary to scientifically configure the amount of flotation reagents according to the properties of the ore to ensure the flotation effect while avoiding reagent waste and environmental pollution.
The gold ore flotation process achieves efficient separation and recovery of target minerals by optimizing the operating conditions of each link, ultimately improving the concentrate grade and comprehensive recovery rate.
Flotation of different types of gold ores
01
Flotation of free gold ore
The gold in free gold ore exists in the form of natural gold or mechanical inclusions, and has a larger particle size, so it is better separated from the gangue minerals. This kind of gold ore is easy to float, and can be floated using xanthate collectors and pine oil frothers. The reagents for free gold flotation are simple and easy to mix.
02
Flotation of refractory gold ores
Refractory gold ores can be divided into two types: sulfide ores and carbon-containing ores. The gold particles in sulfide gold ores coexist with pyrite and arsenopyrite, and the gold particles are distributed in ultrafine particles and are easily wrapped by sulfides. Therefore, it is necessary to enhance the floatability of sulfides during flotation, add yellow medicine and black medicine collectors for flotation collection, and optimize the grinding fineness to achieve full dissociation. When flotating carbon-containing gold ores, it is necessary to add inhibitors such as water glass or perform roasting pretreatment to reduce carbon interference.
Different types of gold ores have different mineralogical characteristics, including mineral particle size, mineral symbiosis, mineral surface properties, etc., which will have a certain impact on the flotation effect. When the gold particles in the ore are finer, the gold ore is more difficult to dissociate, and fine grinding is required, but at the same time, it is also necessary to pay attention to the mudification caused by over-grinding. When gold and sulfide ores coexist, it is necessary to consider the interference effect of the associated ore on flotation. When the surface of the gold ore is attached with an oxide film or is contaminated by organic matter, the floatability of the gold ore decreases, and sodium sulfide or acid washing needs to be added for activation to improve the flotation effect.
Gold flotation reagents
01
Collectors
Common types of collectors for gold flotation include xanthate (butyl xanthate, ethyl xanthate), sulfur xanthate (black xanthate, yellow black xanthate), fatty acid and amine collectors. Xanthate collectors are suitable for the flotation of gold and sulfide paragenetic minerals. They can form a hydrophobic film on the surface of gold, silver and sulfide to increase flotation. Sulfur collectors are suitable for the flotation of refractory gold ores. They can enhance the collection effect of sulfide ores and ultrafine gold particles. Fatty acid and amine collectors are more suitable for the flotation of oxidized ores and non-sulfide gold ores.
02
Frothing agents
Common types of frothers for gold flotation include pine oil, methyl isobutyl carbinol (MIBC), pine tar, etc. The main function of the frother is to reduce the tension of the gas-liquid interface and generate stable bubbles of appropriate size. The size of bubbles will directly affect the recovery rate of gold ore. When the bubbles are too large, the capture efficiency of fine gold particles will decrease. When the bubbles are too small, it will cause the ore particles to settle or the reagents to be wasted.
03
Inhibitors
Common inhibitors for gold flotation include water glass, sodium hydroxide, aluminum sulfate, etc. These inhibitors can inhibit the floatability of gangue minerals such as quartz and calcite, and improve the flotation selectivity of gold minerals. Adding inhibitors can inhibit the adsorption of mud content on reagents and improve the flotation environment.
Challenges and limitations of gold flotation technology
Gold ore often coexists with sulfides, oxides or other minerals. The complexity of the ore composition will increase the difficulty of the beneficiation process. Gold particles are usually finely embedded and difficult to completely dissociate, which requires attention to the use of flotation reagents in the beneficiation process. In addition, other harmful elements in the ore (arsenic, antimony, etc.) will also interfere with the flotation process, thereby affecting the selection of reagents and the final concentrate quality. The following will explain the challenges and limitations of gold flotation technology from three aspects.
01
Difficulties in handling refractory gold ores
Different types of refractory gold ores have their own special problems in the flotation process. For example, sulfide gold ores need to be roasted or bio-oxidized to remove sulfides, which increases the complexity of pretreatment and production costs. The surface hydrophilicity of oxidized gold ores is strong, which makes it difficult for collectors to work effectively and the recovery efficiency is low. There are other valuable metals in associated polymetallic gold ores, which requires the design of long-flow, multi-step processes, so the operational difficulty and cost of mineral processing will increase accordingly.
02
Economic considerations and cost-effectiveness
The economic efficiency of gold flotation technology will directly affect the feasibility of gold flotation projects. The investment in gold flotation equipment, fine grinding equipment and oxidation equipment is large, and the use of reagents will also increase the flotation cost.
03
Common operational problems in gold flotation
Problems such as poor foam stability, low recovery rate, high impurity content and equipment failure will occur in flotation operations. The reason for the unstable foam is improper reagent matching or improper pulp concentration control. Therefore, when this happens, it is necessary to adjust the reagent usage or change the reagent type. The low gold recovery rate may be due to the fact that the gold ore grinding particle size is too coarse or the gold particles are too finely embedded. This situation needs to be improved by optimizing the grinding fineness or replacing the effective collector. The problems in the gold ore flotation process should be analyzed according to the specific situation, and appropriate measures should be taken to adjust the flotation process.
Gold ore flotation is an important process for efficient extraction of gold ore resources. Through the introduction of the above content, we systematically analyzed the flotation process, key operational factors of flotation, flotation of different types of gold ore, and gold ore flotation. The use of reagents and the challenges and limitations of gold mine flotation technology, combined with actual cases, demonstrate the significant advantages of Xinhai Mining in improving gold mine recovery rates and reducing costs. Xinhai Mining is providing comprehensive gold ore separation technical guidance to dressing plant companies to help optimize production efficiency and achieve green and sustainable development.
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