China is rich in titanium resources, ranking first in the world reserves, but 95% occur in the primary vanadium-titanium magnetic iron ore mine, TiO 2 content of less than 10%, and titanium magnetite dense symbiotic, high calcium and magnesium content of impurities, election It is difficult to smelt. The original vanadium-titanium magnetite is mainly distributed in the Panxi area, accounting for more than 90% of the total titanium resources in the country; followed by ilmenite ore, widely distributed in Hainan, Yunnan and Guangdong and Guangxi; in addition, it is also found in Henan. a few large rutile deposits. Foreign ilmenite ore mines are rich in resources. The main producing countries are Australia, South Africa, Ukraine, Norway, etc., and their output accounts for more than 84% of world production.
The content of calcium and magnesium in the original ilmenite is 2 to 3 times higher than that in the sand ore. The content of TiO 2 in the ilmenite concentrate is low. The titanium-rich material obtained after smelting in the electric furnace belongs to the acid-soluble slag and cannot satisfy the sponge. The requirements for the production of raw materials such as titanium and chlorinated titanium dioxide can only be used for the production of titanium dioxide by the sulfuric acid process. With the rapid increase in the demand for chlorinated titanium dioxide and titanium in the international market, the use of China's primary ilmenite resources to solve the problem of high-grade chlorinated slag production and the chlorination of primary ilmenite in Panxi area The production process of the law is the main policy line for the development of China's titanium industry.
From the perspective of the reserves of titanium resources in China, it is worthy of gratification. However, from the perspective of the quality of titanium resources, it is worrying. Therefore, how to effectively utilize the resources of titanium in China has attracted more and more attention. For the time being, the treatment of ilmenite is firstly enriched by beneficiation to obtain titanium concentrate; metallurgical method is further enriched from titanium concentrate to obtain titanium-rich material, and the method of enrichment is mainly There are electric furnace method, acid leaching method and rust reduction method.
I. Research status of ilmenite flotation research
The purpose of ilmenite ore dressing is to pre-enrich the ilmenite ore to improve the grade of TiO 2 in the ilmenite concentrate and reduce the smelting cost. The mineral processing technology of the original ilmenite has been determined by the scientific and technological research for many years. The selection process is determined to be re-election-electrical selection for coarse-grained grades, and strong magnetic-flotation process for fine-grained grades. The flotation collectors used are mainly MOS. As the mining progresses to the deep, the ore tends to be lean, fine and miscellaneous. In order to ensure the grade of the iron concentrate, the magnetic separation tailings need to be finely ground. A large amount of -0.045mm grain-level material is directly discarded as slime, resulting in low recovery of titanium and waste of resources. Therefore, for fine-grained ilmenite, flotation is more and more manifested in its superiority, and people are more devoted to the research of ilmenite full flotation process.
The key to ilmenite flotation is to develop a new and efficient ilmenite collector, optimize the process and reduce production costs. In recent years, ilmenite flotation research mainly focuses on the following two aspects: First, the development of selective and more active ilmenite collectors, and also through the combination of collectors to enhance the capture performance of the agent; On the other hand, it is to improve the existing flotation process, using selective flocculation flotation, carrier flotation, agglomeration flotation and microbubble flotation, etc., to strengthen the selection of fine-grained iron ore.
(I) Research status of ilmenite flotation reagent
The medicaments used in the flotation of ilmenite mainly include collectors, conditioners and foaming agents. In the 1940s and 1950s, people began research on ilmenite flotation. Commonly used collectors for ilmenite flotation are fatty acids such as oxidized paraffin soap, pulp waste and tal oil, hydroxamic acid and its salts, organic phosphonic acid and swollen acid. At this stage, the ore tends to be lean and refined, and the use of a single agent is difficult to achieve the effects of both activity and selectivity, and cannot meet the needs of industrial development. Therefore, the mixed use of existing agents and the synthesis of new agents are the main research directions of ilmenite flotation.
Mixed drugs can achieve better technical indicators and economic benefits than single drugs. The synergistic effect of the agents indicates that two or more agents are used in combination in an optimal ratio, and the effect is often superior to any of the agents. Hu Yongping mixed the alkyl bisphosphonic acid with salicyl hydroxamic acid and floated the artificial mixed minerals, which not only improved the selection index, but also reduced the total consumption of the medicament. When the ratio of the two is 34:15, the salinized water glass is used as the inhibitor, and the pH value is about 6.3. After 1 rough selection and 2 times of selection, the TiO 2 grade can be obtained as 48.32%, and the recovery rate is 75.71%. Titanium concentrate.
Zhu Jianguang mixed the three kinds of collectors and synthesized the MOS collector according to the best ratio. It was adopted by the Panzhihua Titanium Company. In the industrial test, a titanium concentrate having a TiO 2 grade of 47.31% and a recovery of 59.29% can be obtained from a feedstock having a TiO 2 content of 22.52%. After 1 year of production practice, MOS is used as a collector in the field. The grade of concentrate TiO 2 is 47% to 48%, and the recovery rate is 61.6%. Practice has proved that MOS is an effective collector for ilmenite, but MOS collector also has some defects, such as large dosage, it needs to be used together with a variety of modifiers. In response to the shortcomings of MOS, Zhu Jianguang developed a new collector MOH based on MOS collector and conducted industrial tests. The results show that: only using sulfuric acid as the adjusting agent, the grade of titanium concentrate TiO 2 is 47.51%, the recovery rate is 77.66%, which is 16.06 percentage points higher than the recovery rate of MOS.
The combination of a combination of a collector and a non-polar hydrocarbon oil compensates for the deficiencies of the single agent. The hydrocarbon oil covers the surface chelates formed on the mineral surface to form a hydrophobic multi-molecular layer to improve the performance of the collector. Sun Zonghua et al used a mixture of non-polar oil and benzyl sulphonic acid as a collector, and used Pan-flocculation ilmenite by hydrophobic flocculation flotation, using sulfuric acid as a regulator, sodium fluorosilicate as an inhibitor, and ethyl ether alcohol. As a foaming agent, a titanium concentrate having a TiO 2 grade of 45.79% and a recovery rate of 50.52% was obtained from a feedstock having a TiO 2 content of 9.84%. Xu Wei should use oil and coal flotation ilmenite styrene phosphoric acid, can play kerosene was found to accelerate the flotation rate, limit the expansion of flotation size, the amount of styrene reduction, improve the selectivity of the flotation process and improving the foam properties like good results .
In the study of combined collectors, cation collector-anion collector, anion collector-anion collector, non-polar collector-other collectors, collector-foaming agent are often used. Mixtures of collectors, flocculants, etc. to compensate for the lack of activity and selectivity of the mono-agent.
In the aspect of new drug synthesis, research on the effective group of the agent and its flotation mechanism, and design and selection of the drug molecule will contribute to the synthesis of the new high-efficiency collector. Seeing the molecular design of Baixi's introduction of the principle of pharmaceutical design into the flotation agent, Wang Dianzuo proposed the structural performance criteria of various pharmaceuticals, and used quantitative methods to design the drug molecules. These theories provide the basis for the research and development of pharmaceuticals. In the research of fine-grained ilmenite collectors, the development of multi-functional agents and the optimization of pharmaceuticals are one direction for future development.
(II) Research status of ilmenite flotation process
With the deepening of mining, the inlay size of minerals in the ore is finer, and the original production process cannot adapt to the current ore properties. Therefore, the improvement and optimization of the flotation process is an effective way to float fine-grained ilmenite. . Zhu Yangge et al. studied the self-supporting flotation of -20μm fine-grained ilmenite. The results show that the interaction between the coarse and fine grain carriers of ilmenite flotation is significantly affected by the relative content of the two, when the ratio of coarse carrier is above 50%. At the time, the effect from the carrier is better. The experiment was carried out with the actual ore of Panzhihua ilmenite as a test sample. Compared with the flotation process of fine-grained minerals, the recovery rate of -20μm granular ilmenite increased from 52.56% to 61.96%.
For the first time, Fan Xianfeng used microwave energy as a pretreatment technique for ilmenite ore dressing, and studied the application of microwave energy in grinding, magnetic separation and flotation. Microwave selectively heats each mineral in ilmenite, causing strong stress inside the ore, promoting the formation of fine cracks between the phases, and enhancing the intergranular dissociation of the mineral. After the ilmenite has a power of 2600 W and microwave irradiation at a frequency of 2.45 GHz for 60 s, its relative grinding work index is reduced by 80%. At the same time, the ilmenite recovery rate and magnetic separation concentrate grade increase with the applied microwave power level and irradiation time. By microwave irradiation, the ferrous ions on the surface of ilmenite are rapidly oxidized to ferric ions, which enhances the adsorption of oleate ions on the surface. The results of two selective experiments on open-circuit flotation showed that the recovery of TiO 2 increased from 39.8% to 74.8% and the grade increased from 26.2% to 29.9% compared with the conventional method.
Qi Wenqing et al. based on the research of process mineralogy of a ilmenite in Shandong Province, based on the complex composition of ore minerals and fine grain size of minerals, the ore was compared with various experimental schemes, and finally the stage grinding was determined. In the phase selection magnetic separation-flotation combined process, an iron concentrate with an iron grade of 66.42% and a titanium concentrate with a TiO 2 grade of 45.28% were obtained from a ore with an iron content of 19.48% and a TiO 2 content of 9.40%.
Second, the research status of metallurgical treatment of titanium concentrate
The titanium concentrate obtained from the ore dressing is the raw material for the production of titanium-rich material. There are many methods for preparing titanium-rich materials, which can be classified into two types according to the production process: fire method and wet method. The fire method includes an electric furnace smelting method, a selective chlorination method, a plasma smelting method, a microwave thermal reduction method, and the like, and the wet method includes a hydrochloric acid leaching method, a sulfuric acid leaching method, a reduction rust method, a ferric chloride leaching method, and other chemical separation methods. At present, electric furnace smelting method, acid leaching method and reduction rust method are mainly used.
(I) Research status of fire treatment of titanium concentrate
The electric furnace smelting method produces titanium slag by mixing titanium concentrate with solid reducing agent petroleum coke or anthracite, and performing reduction smelting in an electric furnace. The iron oxide in the titanium concentrate is selectively reduced to metallic iron, and the oxidation of titanium The material is enriched to form titanium slag. The main reaction of titanium concentrate during electric furnace smelting is
2FeTiO 3 +CO=Fe+ FeTi 2 O 5 +CO 2 ;
The resulting FeTi 2 O 5 is further reduced, but the iron oxide cannot be all reduced to metallic iron, and a small amount remains in the titanium slag:
(3-x)FeTi 2 O 5 +5(1-x)CO=3(1-x)Fe+2(FexTi l =x )+Ti 2 O 5 +5(1−x)CO 2
The process of preparing titanium slag by electric furnace smelting is simple and mature, and the by-product iron can be directly used. The "three wastes" are few, but only iron can be removed, and non-iron impurities cannot be removed. The characteristics of titanium resources in China are low content of TiO 2 in titanium concentrate and high content of impurities, especially high content of calcium and magnesium. This determines the source of titanium in the domestic furnace (except a small amount of titanium concentrate ore). The slag can only be used as a raw material for the production of titanium dioxide by sulfuric acid.
Rotary kiln treatment method: Fan Xiaohui and others use the rotary kiln direct reduction technology for the Panzhihua titanium concentrate. By means of the catalytic action of the additive, the iron oxide in the titanium concentrate is fully reduced and the iron grain growth is promoted to realize Fe and Ti. Efficient separation. The test results show that the titanium-rich material TiO 2 grade is 74.68 when the additive dosage is 5%, the pellet preheating temperature is 700 °C, the preheating time is 15 min, the reduction temperature is 1100 °C, and the reduction time is 210 min. %, the recovery rate is 90.32%.
Selective chlorination method: using the difference in thermodynamic properties of titanium and iron in titanium concentrate and carbon chlorination, iron is preferentially chlorinated in a neutral or weak reducing atmosphere, volatilized in the form of FeCl 3 ; and titanium is not chlorinated Crystalline transformation occurs at high temperatures to produce artificial rutile. Industrial test was carried out using seashore sand ilmenite as raw material, and the reaction temperature in the furnace was successfully maintained above 950 °C. The obtained artificial rutile grade was 92.13%, and the average purity of FeC1 3 was 96.94%. When using Panzhihua ilmenite (its Mg0 and When the total amount of CaO is 5% to 7%), it is difficult to solve the problem that CaC1 2 and MgC1 2 are enriched at the bottom of the furnace to form a material, thereby reducing the operating life of the furnace.
Microwave heating reduction of titanium concentrate: Huang Mengyang and other microwave-heated reduction of titanium concentrate to obtain titanium-rich material for a kilogram expansion test. Using 20kg pellets, 14% carbon as the reducing agent, the reduction temperature is 1100～1150°C, the proportion of the additive is 5%, and the reduction time is 90min, the TiO 2 grade is 72.01. %, the recovery rate is 90.1% of titanium-rich material. Microwave is a kind of high-efficiency clean energy. It has the characteristics of fast heating, internal heating, selective heating and uniform heating. This process can avoid the problem of serious pollution and high energy consumption in the process of electric furnace smelting and reduction of titanium concentrate.
In recent years, there have been many studies on the treatment of titanium concentrates, but the progress made is not significant, because the fire treatment is more effective for the separation of ferrotitanium, and the non-ferrous impurities in the titanium concentrate reduce the quality of the titanium slag. . Therefore, in order to break through the limitations of the fire treatment of titanium concentrate, it is necessary to reduce the content of impurities in the titanium concentrate, especially the removal of Mg0 and CaO.
(II) Research status of wet processing of titanium concentrate
The acid leaching method firstly reduces the titanium concentrate, converts the iron into ferrous iron, and then leaches the reduced product with the dilute acid, then the iron enters the human liquid phase, and the titanium is concentrated in the solid phase. Acid leaching includes both hydrochloric acid leaching and sulfuric acid leaching. Acid leaching can not only leaching iron, but also impurities such as Mg, Ca, Al, etc., so acid leaching can obtain titanium-rich material with high TiO 2 content, which is suitable for the treatment of Panzhihua high-calcium and magnesium-type titanium concentrate.
Sulfuric acid leaching method: The leaching of sulfuric acid with titanium concentrate as raw material will produce industrial “three wastes†which are difficult to control and pollute the environment. The country has listed it as a restricted industry. 'The use of titanium slag as raw material can reduce acid consumption, solve the problem of by-product ferrous sulfate, reduce environmental pressure and increase equipment production capacity.
Hydrochloric acid leaching method: According to different conditions of acid leaching, it can be divided into high pressure leaching method (Benillite) and atmospheric pressure leaching method (Murso). China's preparation of synthetic rutile has formed two major processes - pre-oxidation - fluidization atmospheric pressure leaching process and combined pressure and leaching process. The pre-oxidation-fluidization atmospheric pressure leaching process can solve the refinement problem of the ore in the leaching process by pre-concentrating the titanium oxide concentrate, and maintain the particle size of the artificial rutile; the smelting and the combined pressure leaching process improves the leaching by pressure leaching effect. Wang Zengjie et al. prepared artificial rutile by using the hydrochloric acid atmospheric direct leaching process for the Panzhihua titanium concentrate, and obtained a product with a TiO 2 content of 94.9%.
The domestic reduction-corrosion method for the production of synthetic rutile began in the 1970s. In 1978, the semi-industrial test of the Guangxi coastal sea-altered ilmenite was successfully carried out and passed the technical appraisal. In 1980, a trial production workshop with an annual output of 2000t rutile was built. Some domestic factories have also established small production workshops, but the production capacity is extremely small, and no scale benefits are formed. The products are mainly used for the production of welding electrodes. The reduction-corrosion method needs to use high-quality titanium concentrate as raw material. The key technology lies in the reduction of titanium concentrate, which requires high reduction temperature, serious ore ringing in the rotary kiln, and the production cannot be continuously carried out, resulting in an increase in cost.
(3) Other new processes
Sun Yan et al. combined with the advantages of microwave heating and the advantages of acid leaching method, proposed a new process of microwave heating selective leaching modified titanium-containing material to obtain high-quality titanium-rich material. The surface of the particles after microwave heating reduction is developed with fine pores, loose structure, and sufficient contact with the leaching agent, and the leaching agent is easy to penetrate into the material to strengthen the reaction. After leaching, the grade of titanium-rich material can reach 96.08%, and the leaching time is shortened by 67%-75% compared with the conventional method.
The Institute of Process Engineering of the Chinese Academy of Sciences has proposed a new process for the clean production of titanium dioxide by the sub-molten salt method. The sub-molten salt method utilizes a pseudo-uniform reaction to decompose ore in a high-concentration medium flowing under normal pressure, which can enhance the reaction, mass and heat transfer, and obtain a higher ore decomposition rate at a lower temperature. The process is applied in the separation of ilmenite, and the titanium in the ilmenite can be selectively and efficiently converted into titanate at a low temperature. After hydrolysis and satin burning, titanium dioxide is obtained, and elements such as iron, calcium and magnesium are not The slag phase is formed by reacting with the sub-molten salt system to realize the selective separation of titanium and iron, and the iron slag can be further resourced, which opens up a new way for the comprehensive utilization of high-calcium-magnesium-type titanium resources in China.
Third, the conclusion
(1) With the continuous development and utilization of titanium resources, the ore tends to be lean and refined, and it is necessary to comprehensively utilize ilmenite, especially the original ilmenite in Panxi, the development of flotation reagents and the improvement of flotation process. It is the main research direction of ilmenite ore dressing, and it is also the unremitting goal of the ore dressing workers. Studies have shown that mixed drugs can make up for the deficiency of single drug and improve the flotation index; and because the mineral inlay size in the ore is finer, the improvement of the flotation process should mainly be carried out around the flotation of fine-grained ilmenite, which improves The comprehensive recovery rate of titanium resources is of great significance.
(2) The rapidly developing titanium industry needs to use high-quality titanium-rich materials as raw materials. The fire treatment of titanium concentrate can not reduce the content of calcium and magnesium impurities, and the content of TiO 2 in titanium slag is low, which is not suitable for the production of chlorinated titanium dioxide. Although wet treatment can effectively reduce the impurity content, it has serious environmental pollution and high energy consumption. Small scale. Therefore, high-calcium-magnesium-type ilmenite restricts the efficient use of titanium resources in China from the source.
(3) With the goal of energy conservation, environmental protection and high efficiency, jointly select mining and metallurgy industry, improve the original process and equipment, develop new technology and open up new research fields, in order to solve the problem of efficient utilization of titanium resources in China.
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