Method for recovering titanium from iron separation tailings of whole-size vanadium titano-magnetite

Abstract

The invention discloses a method for recovering titanium from whole-size vanadium titano-magnetite iron dressing tailings, and belongs to the technical field of mineral processing and metallurgy. According to the method, the whole-size-size vanadium titano-magnetite iron dressing tailings are subjected to suspended-state heating, oxidation is conducted through self heat storage of minerals, part of ilmenite is decomposed, hematite is controlled to be generated on the surfaces of particles preferentially by regulating and controlling technological parameters, then surface magnetization is conducted rapidly under the low-temperature condition, and the iron dressing tailings are obtained. Hematite shell layers on the surfaces of the ilmenite particles are converted into magnetite; gangue is removed through magnetic separation, and synchronous enrichment of titanium and iron is achieved; and the ilmenite product with the magnetic surface is further subjected to ore grinding-magnetic separation, magnetite generated on the surface is ground, stripped and dissociated through ore grinding operation, and then titanium concentrate and iron concentrate products are obtained through magnetic separation. According to the method, the energy consumption in the generation process is effectively reduced, the enterprise cost is greatly reduced, and titanium and iron resources are recycled to the maximum extent.

Description

Technical Field

[0001] The invention belongs to the technical field of mineral processing and metallurgy, and particularly relates to a method for recovering titanium from full-grained vanadium-titanium magnetite iron ore tailings. Background Art

[0002] Titanium is an important strategic resource with the characteristics of high strength, high temperature resistance, low density and strong corrosion resistance. It is widely used in aerospace, military equipment, biochemical industry and other fields. Most titanium is produced mainly from ilmenite.

[0003] At present, the common method of recovering titanium from vanadium-titanium magnetite iron-selected tailings is the traditional ore dressing method, which generally adopts the combined process of magnetic separation, gravity separation, electrostatic separation and flotation for separation. However, due to the fine particle size of vanadium-titanium magnetite iron-selected tailings, the product recovery rate obtained by flotation is low, and the use of flotation reagents is highly polluting and costly, resulting in a large amount of fine-grained vanadium-titanium magnetite iron-selected tailings that cannot be used and are directly discarded as ore mud. Patent CN106179720A discloses a method for recovering ilmenite from vanadium-titanium magnetite iron-selected tailings, firstly magnetically separating the iron-selected tailings to obtain magnetic separation concentrate, and then using a classification method to classify the magnetic separation concentrates of different particle sizes, and using different electrostatic separation, gravity separation and flotation combined processes for coarse and fine particle sizes to extract titanium, and finally obtaining a titanium concentrate product with a TiO2 grade of 46.8% to 47%, but the titanium recovery rate is low, only 18% to 45%, and this method is cumbersome and difficult to implement on a large scale in industry.

[0004] It can be seen that the traditional combined beneficiation processes such as magnetic separation-flotation, magnetic separation-gravity separation, and electrostatic separation are unable to process the tailings of vanadium-titanium magnetite iron ore in full particle size, which results in that the fine-grained tailings of vanadium-titanium magnetite iron ore have not been utilized in industrial production and can only be discarded as ore mud, resulting in serious waste and loss of titanium resources. Therefore, it is of great significance to innovate traditional beneficiation methods and develop a method for recovering titanium from full-size vanadium-titanium magnetite iron ore tailings through interdisciplinary and theoretical breakthroughs. Summary of the invention

[0005] The object of the present invention is to provide a method for recovering titanium from full-grained vanadium-titanium magnetite iron-dressing tailings, by heating the full-grained vanadium-titanium magnetite iron-dressing tailings in a suspended state, and using the mineral's own heat storage for oxidation, so that the ilmenite undergoes oxidative decomposition, and by adjusting the process parameters, the surface of the ilmenite particles is controlled to preferentially generate hematite, and then the reduction magnetization is quickly performed under low temperature conditions, so that the hematite shell layer on the surface of the ilmenite particles is converted into magnetite with strong magnetism, and the inner core of the ilmenite particles is rutile generated by oxidation and decomposition and unreacted ilmenite; then the non-magnetic gangue is discarded by magnetic separation, and the simultaneous enrichment of titanium and iron is achieved. The ilmenite product with magnetic surface is then subjected to grinding-magnetic separation, and the magnetite generated on the surface is ground and dissociated by grinding operation, and finally the ilmenite, rutile and magnetite are separated by magnetic separation to obtain non-magnetic titanium concentrate and magnetic iron concentrate products.

[0006] A method for recovering titanium from full-grained vanadium-titanium magnetite iron ore tailings of the present invention is carried out according to the following steps:

[0007] Step 1: preheat the vanadium-titanium magnetite iron ore tailings in a cyclone preheater to obtain a preheated product, so that the raw material is dried and dehydrated.

[0008] Step 2: The obtained preheated product is subjected to suspended high-temperature heating in a suspension roasting furnace to obtain a high-temperature heated product. The high-temperature heated product and gas enter a cyclone separator for gas-solid separation. The gas enters the cyclone preheater and returns to step 1 as a heating gas.

[0009] Step 3: The vanadium-titanium magnetite iron ore tailings heated in the suspension roasting furnace use their own heat to oxidatively roast the high-temperature heated product in an oxidation roasting furnace to obtain an oxidatively roasted product. The oxidative roasting temperature is 700°C to 800°C, and the oxidative roasting time is 5min to 20min, so that hematite is preferentially generated on the surface of the ilmenite particles, and the inner core of the ilmenite particles is rutile (TiO2) generated by oxidation decomposition and unreacted ilmenite. The product enters the cyclone separator through a pipeline for gas-solid separation, and the gas is fed into the suspension roasting furnace as a heating gas and returned to step 2; the main chemical reaction formulas involved in step 3 are as follows:

[0010] 4FeTiO3+O2=2Fe2O3+4TiO2(1)

[0011] Step 4: The oxidized roasted product is sent to a reduction roasting furnace for magnetization roasting using the heat of the oxidized mineral itself to obtain a magnetized roasted product, so that the hematite in the oxidized roasted product is reduced to magnetite, thus having strong magnetism. The main chemical reaction formula is:

[0012] 3Fe2O3+CO / H2=2Fe3O4+CO2 / H2O(2)

[0013] Step 5: The magnetized roasting product is separated into gas and solid and cooled by a cyclone separator. The separated gas is fed into the suspension roasting furnace as heating gas for combustion and heat supply. The product cooled by the cyclone separator enters the cooling tank for water quenching to prevent oxidation.

[0014] Step 6: The product after water quenching enters the magnetic separator for magnetic separation to separate the magnetized ilmenite from the gangue minerals to obtain magnetic ilmenite products and non-magnetic gangue products, thereby simultaneously enriching and recovering iron and titanium.

[0015] Step 7: The enriched magnetic ilmenite product enters a stirred mill or an abrasive mill for scrubbing and grinding, and is ground to a particle size of -325 mesh ≥ 80%. The magnetite layer with magnetic properties on the surface is dissociated by grinding and stripping, and finally a magnetic separation is performed to separate iron and titanium to obtain non-magnetic titanium concentrate and magnetic iron concentrate products.

[0016] In the above step 1, the particle size of the vanadium-titanium magnetite iron ore tailings is -200 mesh content ≥80%, of which -400 mesh content is more than 30%, wherein the TFe grade in the vanadium-titanium magnetite iron ore tailings is 8% to 30%, the TiO2 grade is 5% to 25%, and the moisture content is ≤10%.

[0017] In the above step 1, the preheating temperature is 300° C. to 500° C., and the time is 1 min to 3 min.

[0018] In the above step 2, the suspension roasting furnace can generate heat by burning coal gas, and the coal gas used is coke oven gas, blast furnace gas and / or gas obtained by cracking natural gas. It also includes heating gas generated by oxidative roasting and magnetic roasting as a heat source.

[0019] In the above step 2, during the suspended high-temperature heating process, the heating temperature is 800° C. to 900° C., and the heating time is 1 min to 5 min.

[0020] In the above step 3, the oxidizing gas introduced during the oxidative roasting process is a mixed gas of nitrogen and oxygen with an O2 concentration greater than 10%, or directly uses air.

[0021] In the above step 4, the reduction roasting furnace is a fluidized reactor, the material magnetization roasting temperature is 500°C to 600°C, the magnetization roasting time is 2min to 15min, the reducing gas introduced during the magnetization roasting process is hydrogen, CO or a mixed gas thereof, the reducing gas concentration is 10% to 60%, and the rest is nitrogen.

[0022] The oxidation roasting furnace and reduction roasting furnace described in the above steps 3 and 4 are devices that support the particles to react in a suspended or fluidized state.

[0023] In the above step 5, the material temperature after water quenching is not higher than 80°C.

[0024] In the above step 6, the magnetic field strength is 1000Oe to 2000Oe.

[0025] In the above step 7, the magnetic field strength is 500Oe to 1200Oe.

[0026] In the above step 7, the TiO2 grade of the obtained titanium concentrate product is ≥47%, and the titanium recovery rate is ≥70%; the TFe grade of the obtained iron concentrate product is ≥54%.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The technical principle of the present invention is to suspend and roast the whole particle size of the vanadium-titanium magnetite iron ore tailings, so that the hematite generated by oxidation and decomposition of the ilmenite surface in the iron ore tailings is quickly reduced to magnetite under low temperature conditions (500°C to 600°C), thereby increasing the magnetism of the ilmenite. Due to the change in surface magnetism, the ilmenite and gangue minerals in the iron ore tailings can be separated by magnetic separation, and the initial enrichment of ilmenite can be achieved to obtain magnetic ilmenite products and non-magnetic gangue products. Further, by scrubbing and grinding treatment, the newly formed magnetite on the surface of the ilmenite is ground and dissociated during the grinding process, and the inner core of the ilmenite particles is a mixed mineral mainly composed of ilmenite and rutile. Then, the titanium-containing mixed minerals are separated from the magnetite by magnetic separation, and non-magnetic titanium concentrate and magnetic iron concentrate products are obtained respectively.

[0029] The new technology of suspension heating-heat storage oxidation-magnetization roasting-magnetic separation-grinding-remagnetic separation of the present invention can effectively recover the exhaust gas during the roasting process, and the waste heat can be fully recycled. The technology effectively solves the problem that the ilmenite particles are too fine to be used for flotation, and can realize the comprehensive recovery of full-grained ilmenite in the tailings of vanadium-titanium magnetite iron beneficiation, and effectively avoids the problem of large loss of fine-grained ilmenite caused by the pre-classification and desludging process. In addition, during the treatment process, the heat of the mineral itself after suspension roasting and heating is first used for oxidation roasting, and the heat generated in the oxidation roasting process is fully utilized to maintain the reaction, saving energy and reducing carbon; secondly, low-temperature magnetic roasting is used to reduce only the hematite generated on the surface of the ilmenite particles during the oxidation roasting process to magnetite, and the interior of the ilmenite does not participate in the chemical reaction, which greatly reduces energy consumption and generation costs. Subsequently, the grinding and magnetic separation technologies in traditional ore dressing are used to separate the magnetite from the ilmenite, and iron concentrate and titanium concentrate are obtained respectively, realizing the comprehensive recovery and utilization of titanium and iron, and effectively improving the resource utilization rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of a process for recovering titanium from full-size vanadium-titanium magnetite iron ore tailings in an embodiment of the present invention;

[0031] Figure 2These are SEM images and energy spectrum diagrams of the oxidative roasting product and the magnetized roasting product of Example 1 of the present invention; wherein (a) and (b) are SEM images of the oxidative roasting product, (c) and (d) are SEM images of the magnetized roasting product, (e) and (f) are energy spectrum analysis diagrams, and 1, 2, 3, and 4 in the diagram represent the element distribution at different points. DETAILED DESCRIPTION

[0032] Example 1

[0033] A method for recovering titanium from full-size vanadium-titanium magnetite iron ore tailings, such as Figure 1 As shown, follow these steps:

[0034] Step 1: Preheat the vanadium-titanium magnetite iron ore tailings raw material with TFe grade of 8.5%, TiO2 grade of 18.7%, moisture content of 10%; particle size of -200 mesh accounting for 95%, of which -400 mesh accounting for 40% in a cyclone preheater, the preheating temperature is 300 ° C, the preheating time is 2 minutes, so that the raw material is dried and dehydrated.

[0035] Step 2: The preheated product is fed into a suspension roasting furnace for heating. The suspension roasting furnace provides heat by burning natural gas. The temperature in the furnace rises to 850°C. The product is heated in the suspension roasting furnace for 4 minutes. After heating, the product enters the first cyclone separator for gas-solid separation. The separated gas is returned to the cyclone preheater in step 1 as heating gas.

[0036] Step 3: The vanadium-titanium magnetite iron tailings heated in the suspension roaster are subjected to oxidation roasting in an oxidation roaster by utilizing their own heat storage to obtain an oxidation roasting product. The oxidizing gas is air, the oxidation roasting temperature is 700°C, and the oxidation roasting time is 15 minutes, so that the surface of the ilmenite particles is enriched to form hematite, and the core of the ilmenite particles is rutile (TiO2) generated by oxidation decomposition and unreacted ilmenite. The oxidation roasting product enters the second cyclone separator for gas-solid separation again, and the separated gas is fed into the suspension roaster of step 2 as heating gas.

[0037] Step 4: The oxidized roasted product enters a reduction roasting furnace and is magnetized and roasted using the heat of the oxidized mineral particles themselves. The reducing gas is H2 with a concentration of 40%. The magnetization roasting temperature is 500°C and the magnetization roasting time is 5 minutes. The hematite in the oxidized roasted product is reduced to magnetite, which has strong magnetism.

[0038] The SEM images and energy spectra of the products calcined by oxidation and magnetization in steps 3 and 4 are as follows: Figure 2 As shown, Figure 2(a) and (b) are SEM images of oxidation roasted products, (c) and (d) are SEM images of magnetization roasted products, and (e) and (f) are energy spectrum analysis diagrams to show the element distribution of different points (Spot 1, Spot 2, Spot 3 and Spot 4) in Figures (a)-(d). Figure 2 It can be clearly seen that after the ilmenite in the vanadium-titanium magnetite iron ore tailings is oxidized and roasted, a layer of hematite is generated on the surface. After magnetized roasting, the generated hematite is transformed into magnetite, and a product wrapped by magnetite is obtained; both hematite and magnetite wrap the ilmenite on the outside.

[0039] Table 1 Figure 2 EDS spectrum analysis results of the corresponding points in (mass percentage, %)

[0040]

[0041]

[0042] Step 5: The magnetized roasted product is separated from the gas and solid by the third cyclone separator and cooled, and the separated gas is fed into the suspension roasting furnace in step 2 as heating gas. The product cooled by the cyclone separator enters the cooling tank for water quenching to prevent oxidation. The material temperature after water quenching is not higher than 80°C.

[0043] Step 6: The product after water quenching enters a magnetic separator for magnetic separation to separate the magnetized ilmenite from the gangue minerals to obtain magnetic ilmenite and non-magnetic gangue, wherein the magnetic separation field strength is 1500Oe.

[0044] Step 7: The magnetic ilmenite product obtained by magnetic separation is placed in a stirred mill for scrubbing and grinding. The particle size of the grinding product is -325 mesh, accounting for 80%. The outer shell of the magnetite with strong magnetic properties on the surface is dissociated by grinding and stripping. Finally, magnetic separation is carried out again with a magnetic separation field strength of 600Oe to achieve iron and titanium separation, and a titanium concentrate product with a TiO2 grade of 48.12% and a recovery rate of 79.12%, as well as an iron concentrate product with a TFe grade of 54.52% are obtained.

[0045] Example 2

[0046] A method for recovering titanium from full-size vanadium-titanium magnetite iron ore tailings is carried out according to the following steps:

[0047] Step 1: Preheat the vanadium-titanium magnetite iron ore tailings raw material with TFe grade of 10.35%, TiO2 grade of 17.62%, moisture content of 9%; particle size of -200 mesh accounting for 90%, of which -400 mesh accounting for 50% in a cyclone preheater, the preheating temperature is 300 ° C, the preheating time is 2 minutes, so that the raw material is dried and dehydrated.

[0048] Step 2: The preheated product is fed into a suspension roasting furnace for heating. The suspension roasting furnace provides heat by burning natural gas. The temperature in the furnace rises to 900°C. The product is heated in the suspension roasting furnace for 2 minutes. After heating, the product enters the first cyclone separator for gas-solid separation. The separated gas is returned to the cyclone preheater in step 1 as heating gas.

[0049] Step 3: The vanadium-titanium magnetite iron tailings heated in the suspension roaster are subjected to oxidation roasting in an oxidation roaster by utilizing their own heat storage to obtain an oxidation roasting product. The oxidizing gas is air, the oxidation roasting temperature is 700°C, and the oxidation roasting time is 15 minutes, so that the surface of the ilmenite particles is enriched to form hematite, and the core of the ilmenite particles is rutile (TiO2) generated by oxidation decomposition and unreacted ilmenite. The oxidation roasting product enters the second cyclone separator for gas-solid separation again, and the separated gas is fed into the suspension roaster of step 2 as heating gas.

[0050] Step 4: The oxidized roasted product enters a reduction roasting furnace and is magnetized and roasted using the heat of the oxidized mineral particles themselves. The reducing gas is H2 with a concentration of 40%. The magnetization roasting temperature is 550°C and the magnetization roasting time is 5 minutes. The hematite in the oxidized roasted product is reduced to magnetite, which has strong magnetism.

[0051] Step 5: The magnetized roasted product is separated from the gas and solid by the third cyclone separator and cooled, and the separated gas is fed into the suspension roasting furnace in step 2 as heating gas. The product cooled by the cyclone separator enters the cooling tank for water quenching to prevent oxidation. The material temperature after water quenching is not higher than 80°C.

[0052] Step 6: The product after water quenching enters a magnetic separator for magnetic separation to separate the magnetized ilmenite from the gangue minerals to obtain magnetic ilmenite and non-magnetic gangue, wherein the magnetic separation field strength is 1600 Oe.

[0053] Step 7: The magnetic ilmenite product obtained by magnetic separation is placed in a stirred mill for scrubbing and grinding. The particle size of the grinding product is -325 mesh, accounting for 80%. The outer shell of the magnetite with strong magnetic properties on the surface is dissociated by grinding and stripping. Finally, magnetic separation is carried out again with a magnetic separation field strength of 800Oe to achieve iron and titanium separation, and a titanium concentrate product with a TiO2 grade of 48.55% and a recovery rate of 80.23%, as well as an iron concentrate product with a TFe grade of 55.31%.

[0054] Example 3

[0055] A method for recovering titanium from full-size vanadium-titanium magnetite iron ore tailings is carried out according to the following steps:

[0056] Step 1: Preheat the vanadium-titanium magnetite iron ore tailings raw material with TFe grade of 12.58%, TiO2 grade of 19.33%, moisture content of 10%; particle size of -200 mesh accounting for 95%, of which -400 mesh accounting for 60% in a cyclone preheater, the preheating temperature is 350 ° C, the preheating time is 3 minutes, so that the raw material is dried and dehydrated.

[0057] Step 2: The preheated product is fed into a suspension roasting furnace for heating. The suspension roasting furnace provides heat by burning natural gas. The temperature in the furnace rises to 900°C. The product is heated in the suspension roasting furnace for 3 minutes. After heating, the product enters the first cyclone separator for gas-solid separation. The separated gas is returned to the cyclone preheater in step 1 as heating gas.

[0058] Step 3: The vanadium-titanium magnetite iron tailings heated in the suspension roaster are subjected to oxidation roasting in an oxidation roaster by utilizing their own heat storage to obtain an oxidation roasting product. The oxidizing gas is air, the oxidation roasting temperature is 750°C, and the oxidation roasting time is 10 minutes, so that the surface of the ilmenite particles is enriched to form hematite, and the core of the ilmenite particles is rutile (TiO2) generated by oxidation decomposition and unreacted ilmenite. The oxidation roasting product enters the second cyclone separator for gas-solid separation again, and the separated gas is fed into the suspension roaster of step 2 as heating gas.

[0059] Step 4: The oxidized roasted product enters a reduction roasting furnace and uses the heat of the oxidized mineral itself for surface magnetization. The reducing gas is H2 with a concentration of 40%. The magnetization roasting temperature is 580°C and the magnetization roasting time is 5 minutes. The hematite in the oxidized roasted product is reduced to magnetite, which has strong magnetism.

[0060] Step 5: The magnetized roasted product is separated from the gas and solid by the third cyclone separator and cooled, and the separated gas is fed into the suspension roasting furnace in step 2 as heating gas. The product cooled by the cyclone separator enters the cooling tank for water quenching to prevent oxidation. The material temperature after water quenching is not higher than 80°C.

[0061] Step 6: The product after water quenching enters the magnetic separator for magnetic separation to separate the magnetized ilmenite from the gangue minerals. The magnetic separation field strength is 1500Oe.

[0062] Step 7: The magnetic ilmenite product obtained by magnetic separation is placed in a stirred mill for scrubbing and grinding. The particle size of the grinding product is -325 mesh, accounting for 80%. The outer shell of the magnetite with strong magnetic properties on the surface is dissociated by grinding and stripping. Finally, magnetic separation is carried out again with a magnetic separation field strength of 700Oe to achieve iron and titanium separation, and a titanium concentrate product with a TiO2 grade of 49.04% and a recovery rate of 80.11% and an iron concentrate product with a TFe grade of 55.45% are obtained.

[0063] Example 4

[0064] A method for recovering titanium from full-size vanadium-titanium magnetite iron ore tailings is carried out according to the following steps:

[0065] Step 1: Preheat the vanadium-titanium magnetite iron ore tailings raw material with TFe grade of 15.35%, TiO2 grade of 22.38%, moisture content of 8%; particle size of -200 mesh accounting for 90%, of which -400 mesh accounting for 60% in a cyclone preheater, the preheating temperature is 350 ° C, the preheating time is 2 minutes, so that the raw material is dried and dehydrated.

[0066] Step 2: The preheated product is fed into a suspension roasting furnace for heating. The suspension roasting furnace provides heat by burning natural gas. The temperature in the furnace rises to 850°C. The product is heated in the suspension roasting furnace for 4 minutes. After heating, the product enters the first cyclone separator for gas-solid separation. The separated gas is returned to the cyclone preheater in step 1 as heating gas.

[0067] Step 3: The vanadium-titanium magnetite iron tailings heated in the suspension roaster are subjected to oxidation roasting in an oxidation roaster by utilizing their own heat storage to obtain an oxidation roasting product. The oxidizing gas is air, the oxidation roasting temperature is 750°C, and the oxidation roasting time is 18 minutes, so that the surface of the ilmenite particles is enriched to form hematite, and the core of the ilmenite particles is rutile (TiO2) generated by oxidation decomposition and unreacted ilmenite. The oxidation roasting product enters the second cyclone separator for gas-solid separation again, and the separated gas is fed into the suspension roaster of step 2 as heating gas.

[0068] Step 4: The oxidized roasted product enters a reduction roasting furnace and uses the heat of the oxidized mineral itself for surface magnetization. The reducing gas is H2 with a concentration of 50%. The magnetization roasting temperature is 550°C and the magnetization roasting time is 5 minutes. The hematite in the oxidized roasted product is reduced to magnetite, which has strong magnetism.

[0069] Step 5: The magnetized roasted product is separated from the gas and solid by the third cyclone separator and cooled, and the separated gas is fed into the suspension roasting furnace in step 2 as heating gas. The product cooled by the cyclone separator enters the cooling tank for water quenching to prevent oxidation. The material temperature after water quenching is not higher than 80°C.

[0070] Step 6: The product after water quenching enters the magnetic separator for magnetic separation to separate the magnetized ilmenite from the gangue minerals. The magnetic separation field strength is 1100Oe.

[0071] Step 7: The magnetic ilmenite product obtained by magnetic separation is placed in a stirred mill for scrubbing and grinding. The particle size of the grinding product is -325 mesh, accounting for 75%. The outer shell of the magnetite with strong magnetic properties on the surface is dissociated by grinding and stripping. Finally, magnetic separation is carried out again with a magnetic separation field strength of 500Oe to achieve iron and titanium separation, and a titanium concentrate product with a TiO2 grade of 47.18% and a recovery rate of 78.10% and an iron concentrate product with a TFe grade of 55.71% are obtained.

[0072] Example 5

[0073] A method for recovering titanium from full-size vanadium-titanium magnetite iron ore tailings is carried out according to the following steps:

[0074] Step 1: Preheat the vanadium-titanium magnetite iron ore tailings raw material with TFe grade of 17.25%, TiO2 grade of 20.31%, moisture content of 10%; particle size of -200 mesh accounting for 85%, of which -400 mesh accounting for 55% in a cyclone preheater, the preheating temperature is 350 ° C, the preheating time is 2 minutes, so that the raw material is dried and dehydrated.

[0075] Step 2: The preheated product is fed into a suspension roasting furnace for heating. The suspension roasting furnace provides heat by burning natural gas. The temperature in the furnace rises to 850°C. The product is heated in the suspension roasting furnace for 5 minutes. After heating, the product enters the first cyclone separator for gas-solid separation. The separated gas is returned to the cyclone preheater in step 1 as heating gas.

[0076] Step 3: The vanadium-titanium magnetite iron tailings heated in the suspension roaster are subjected to oxidation roasting in an oxidation roaster by utilizing their own heat storage to obtain an oxidation roasting product. The oxidizing gas is air, the oxidation roasting temperature is 700°C, and the oxidation roasting time is 20 minutes, so that the surface of the ilmenite particles is enriched to form hematite, and the core of the ilmenite particles is rutile (TiO2) generated by oxidation decomposition and unreacted ilmenite. The oxidation roasting product enters the second cyclone separator for gas-solid separation again, and the separated gas is fed into the suspension roaster of step 2 as heating gas.

[0077] Step 4: The oxidized roasted product enters a reduction roasting furnace and uses the heat of the oxidized mineral itself to magnetize the surface. The reducing gas is H2 with a concentration of 50%. The magnetization roasting temperature is 550°C and the magnetization roasting time is 10 minutes. The hematite in the oxidized roasted product is reduced to magnetite, which has strong magnetism.

[0078] Step 5: The magnetized roasted product is separated from the gas and solid by the third cyclone separator and cooled, and the separated gas is fed into the suspension roasting furnace in step 2 as heating gas. The product cooled by the cyclone separator enters the cooling tank for water quenching to prevent oxidation. The material temperature after water quenching is not higher than 80°C.

[0079] Step 6: The product after water quenching enters the magnetic separator for magnetic separation to separate the magnetized ilmenite from the gangue minerals. The magnetic separation field strength is 1200Oe.

[0080] Step 7: The magnetic ilmenite product obtained by magnetic separation is placed in a stirred mill for scrubbing and grinding. The particle size of the grinding product is -325 mesh, accounting for 75%. The outer shell of the magnetite with strong magnetic properties on the surface is dissociated by grinding and stripping. Finally, magnetic separation is carried out again with a magnetic separation field strength of 600Oe to achieve iron and titanium separation, and a titanium concentrate product with a TiO2 grade of 48.11% and a recovery rate of 75.34%, as well as an iron concentrate product with a TFe grade of 55.11% are obtained.

[0081] Example 6

[0082] A method for recovering titanium from full-size vanadium-titanium magnetite iron ore tailings is carried out according to the following steps:

[0083] Step 1: Preheat the vanadium-titanium magnetite iron ore tailings raw material with TFe grade of 20.35%, TiO2 grade of 24.22%, moisture content of 10%; particle size of -200 mesh accounting for 80%, of which -400 mesh accounting for 55% in a cyclone preheater, the preheating temperature is 400 ° C, the preheating time is 2 minutes, so that the raw material is dried and dehydrated.

[0084] Step 2: The preheated product is fed into a suspension roasting furnace for heating. The suspension roasting furnace provides heat by burning natural gas. The temperature in the furnace rises to 900°C. The product is heated in the suspension roasting furnace for 5 minutes. After heating, the product enters the first cyclone separator for gas-solid separation. The separated gas is returned to the cyclone preheater in step 1 as heating gas.

[0085] Step 3: The vanadium-titanium magnetite iron tailings heated in the suspension roaster are oxidized and roasted in an oxidation roaster to obtain an oxidized roasted product by using their own heat storage. The oxidizing gas is air, the oxidizing roasting temperature is 750°C, and the oxidizing roasting time is 15 minutes, so that the surface of the ilmenite particles is enriched to form hematite, and the core of the ilmenite particles is rutile (TiO2) generated by oxidation and decomposition and unreacted ilmenite. The pre-oxidation product enters the second cyclone separator for solid-gas separation again, and the separated gas is fed into the suspension heating roaster.

[0086] Step 4: The oxidized roasted product enters the reduction roasting furnace and uses the heat of the oxidized mineral itself for surface magnetization. The reducing gas is H2 with a concentration of 50%. The magnetization roasting temperature is 520°C and the magnetization roasting time is 8 minutes. The hematite in the pre-oxidized product is reduced to magnetite, which has strong magnetism.

[0087] Step 5: The magnetized roasted product is separated from the gas and solid by the third cyclone separator and cooled, and the separated gas is fed into the suspension roasting furnace in step 2 as heating gas. The product cooled by the cyclone separator enters the cooling tank for water quenching to prevent oxidation. The material temperature after water quenching is not higher than 80°C.

[0088] Step 6: The product after water quenching enters the magnetic separator for magnetic separation to separate the magnetized ilmenite from the gangue minerals. The magnetic separation field strength is 2000Oe.

[0089] Step 7: The magnetic ilmenite product obtained by magnetic separation is placed in a stirred mill for scrubbing and grinding. The particle size of the grinding product is -325 mesh, accounting for 85%. The outer shell of the magnetite with strong magnetic properties on the surface is dissociated by grinding and stripping. Finally, magnetic separation is carried out again with a magnetic separation field strength of 1200Oe to achieve iron and titanium separation, and a titanium concentrate product with a TiO2 grade of 47.28% and a recovery rate of 76.23%, as well as an iron concentrate product with a TFe grade of 54.81%.

Claims

1. A method for recovering titanium from full-size vanadium-titanium magnetite iron ore tailings, characterized in that: Follow these steps: Step 1: preheating the vanadium-titanium magnetite iron ore tailings in a cyclone preheater to obtain a preheated product, so that the raw material is dried and dehydrated; Step 2: The obtained preheated product is subjected to suspended high-temperature heating in a suspension roasting furnace to obtain a high-temperature heated product, and the high-temperature heated product and gas are subjected to gas-solid separation, and the gas enters a cyclone preheater and is returned to step 1 as a heating gas; Step 3: The vanadium-titanium magnetite iron ore tailings heated in the suspension roasting furnace are subjected to oxidation roasting in an oxidation roasting furnace using their own heat to obtain an oxidation roasting product. The oxidation roasting temperature is 700°C to 800°C, and the oxidation roasting time is 5min to 20min, so that hematite is preferentially generated on the surface of the ilmenite particles, and the inner core of the ilmenite particles is rutile generated by oxidation decomposition and unreacted ilmenite. The product is subjected to gas-solid separation, and the gas is fed into the suspension roasting furnace as a heating gas and returned to step 2; the main chemical reaction formula is as follows: 4FeTiO3+O2=2Fe2O3+4TiO2 (1) Step 4: The oxidized roasted product is sent to a reduction roasting furnace for magnetization roasting using the heat of the oxidized mineral itself to obtain a magnetized roasted product, so that the hematite in the oxidized roasted product is reduced to magnetite, thus having strong magnetism. The main chemical reaction formula is: 3Fe2O3+CO / H2=2Fe3O4+CO2 / H2O (2) Step 5: The magnetized roasted product is subjected to gas-solid separation and cooling, and the separated gas is fed into the suspension roasting furnace as heating gas for combustion and heat supply, and the cooled product enters the cooling tank for water quenching to prevent oxidation; Step 6: The product after water quenching enters the magnetic separator for magnetic separation, so as to separate the magnetized ilmenite from the gangue minerals, and obtain the magnetic ilmenite product and the non-magnetic gangue product, thereby simultaneously enriching and recovering iron and titanium; Step 7: The enriched magnetic ilmenite product is scrubbed and ground to a particle size of -325 mesh ≥ 80%, and the magnetite layer with magnetic properties on the surface is dissociated by grinding and stripping, and finally a magnetic separation is performed to separate iron and titanium to obtain non-magnetic titanium concentrate and magnetic iron concentrate products.

2. A method for recovering titanium from full-size vanadium-titanium magnetite iron ore tailings according to claim 1, characterized in that: The particle size of the vanadium-titanium magnetite iron ore tailings in step 1 is ≥80% at -200 mesh, and more than 30% at -400 mesh. The TFe grade in the vanadium-titanium magnetite iron ore tailings is 8% to 30%, the TiO2 grade is 5% to 25%, and the moisture content is ≤10%.

3. A method for recovering titanium from full-size vanadium-titanium magnetite iron ore tailings according to claim 1, characterized in that: In the step 1, the preheating temperature is 300° C. to 500° C., and the preheating time is 1 min to 3 min.

4. A method for recovering titanium from full-size vanadium-titanium magnetite iron ore tailings according to claim 1, characterized in that: In the step 2, during the suspended high-temperature heating process, the heating temperature is 800° C. to 900° C., and the heating time is 1 min to 5 min.

5. A method for recovering titanium from full-size vanadium-titanium magnetite iron ore tailings according to claim 1, characterized in that: In step 3, the oxidizing gas is a mixed gas of N2 / O2>10% or air is used directly.

6. A method for recovering titanium from full-size vanadium-titanium magnetite iron ore tailings according to claim 1, characterized in that: In step 4, the reduction roasting furnace is a fluidized reactor, the material magnetization roasting temperature is 500° C. to 600° C., the magnetization roasting time is 2 min to 15 min, and the reducing gas introduced during the magnetization roasting process is hydrogen, CO or a mixed gas thereof.

7. A method for recovering titanium from full-size vanadium-titanium magnetite iron ore tailings according to claim 1, characterized in that: In the step 5, the material temperature after water quenching is not higher than 80°C.

8. A method for recovering titanium from full-size vanadium-titanium magnetite iron ore tailings according to claim 1, characterized in that: In step 6, the magnetic field strength is 1000Oe to 2000Oe.

9. A method for recovering titanium from full-size vanadium-titanium magnetite iron ore tailings according to claim 1, characterized in that: In step 7, the magnetic field strength is 500 Oe to 1200 Oe.

10. A method for recovering titanium from full-size vanadium-titanium magnetite iron ore tailings according to claim 1, characterized in that: In step 7, the TiO2 grade in the obtained titanium concentrate product is ≥47%, the recovery rate is ≥70%, and the TFe grade in the iron concentrate product is ≥54%.

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