Composite furnace charge for yellow phosphorus smelting and preparation method thereof

Abstract

According to the composite furnace charge for yellow phosphorus smelting and the preparation method thereof, waste phosphorite powder generated in the phosphorite raw ore mining, processing and utilization process and ash generated in the yellow phosphorus production process are combined for pelletizing and sintering, artificial phosphorite pellets meeting the yellow phosphorus production requirement are obtained, the utilization efficiency of phosphorus resources is greatly improved, and the production cost is reduced. Meanwhile, raw phosphorite ore is subjected to thermal decomposition treatment in advance, decarbonized phosphorite lump ore is obtained and then compounded with artificial phosphorite pellets to serve as yellow phosphorus production furnace charge, the content of carbonate in the furnace charge is reduced, and the acidity stability of the furnace charge is ensured; therefore, the pulverization rate of the furnace burden is obviously reduced, the energy consumption is greatly reduced, and the economic benefit is obvious.

Description

Technical Field

[0001] The invention relates to yellow phosphorus production technology, in particular to a composite furnace charge for yellow phosphorus smelting and a preparation method thereof, belonging to the technical field of yellow phosphorus production. Background Art

[0002] Yellow phosphorus is an important chemical product and raw material, and its products are widely used in agriculture, industry, national defense, food, electronics, and other fields. Modern yellow phosphorus smelting uses natural phosphate rock as raw material. After adding a certain proportion of coke, the charge is melted in an electric furnace at a high temperature of 1400-1500°C, undergoing a reduction reaction. The phosphorus element rises with the furnace gas and is discharged from the furnace top for subsequent recovery.

[0003] The quality requirements of phosphate rock for yellow phosphorus production by electric furnace method mainly include: (1) the higher the grade (P2O5 content), the better; the lower the grade, the higher the amount of phosphorus slag and electric furnace power consumption; (2) the particle size requirement is >5mm. On the one hand, the material column in the electric furnace is required to have good air permeability to ensure the rise of phosphorus vapor; on the other hand, the increase of powder in the charge will lead to an increase in the amount of mud phosphorus, which is not conducive to the recovery of yellow phosphorus; (3) higher physical strength to minimize the degree of pulverization during transportation, pretreatment and after entering the electric furnace; (4) as low as possible moisture content and ignition loss (i.e. carbonate content) to reduce the energy consumption of water evaporation and carbonate decomposition.

[0004] For decades, the phosphate rock used in yellow phosphorus smelting has primarily been natural lump ore with a particle size of 5mm-50mm. Currently, the raw material processing for most electric phosphorus furnaces in my country is relatively simple: after mining, the phosphate rock is crushed and screened before being transported to the plant. It is then dried and screened within the plant before being stored in the silo. However, this raw material and its usage conditions present numerous challenges. First of all, phosphate rock is a non-renewable resource. After decades of mining and utilization, high-quality phosphate lumps with high grade and few impurities are becoming increasingly scarce. Its market price has also soared with the hot yellow phosphorus market in recent years, and the price has continued to run at a high level. At the same time, most of my country's phosphate rock resources are weathered calcareous phosphate rocks, and the strength of the lumps is relatively low. During the ore mining, transportation, and in-plant drying and screening processes, a high amount of powder ore is generated, and a large amount of accumulation cannot be directly used by electric furnaces. The total powder rate of some yellow phosphorus plants is as high as 60%. Although there are enterprises and research institutes that use various binders to make these phosphorus-containing dusts into balls, there are problems such as high binder cost and heat resistance, and the binder is pulverized during the production of yellow phosphorus, which has no effect. In addition, due to the large amount of binder, the production process is not very effective. The addition of binder further depletes the grade of phosphate rock. If the amount of binder used is small, it is difficult to mix the materials evenly, the quality of the pellets is unstable, the pelletizing rate is low, and it is not suitable for pelletizing phosphate rock powder with high ignition loss and for yellow phosphorus production. Secondly, natural phosphorus lump ore has poor thermal strength. During the process of running from top to bottom in the electric furnace, thermal stress is generated in the lump ore as the temperature increases. Under the action of external forces such as charge pressure and lining friction, it is crushed. The new powder and the -5mm powder that enters the electric furnace due to incomplete screening block the air flow channel together. At the same time, the fine particles generated are discharged with the furnace gas and form mud phosphorus when the phosphorus vapor condenses, reducing the yellow phosphorus yield and increasing the unit energy consumption. Finally, the carbonate content in the phosphorus lump ore is 5% to 8%, and the moisture is not completely dried. The heat consumption when entering the electric furnace is high, which increases the energy consumption of the electric furnace. Furthermore, electric furnace smelting typically requires the addition of large amounts of flux (such as silica) to adjust the charge's acidity (SiO2 / CaO) to around 0.8. This unstable raw material composition can cause fluctuations in the charge ratio, impacting furnace operation. Typically, producing one ton of yellow phosphorus consumes approximately 14,000 kW·h of electricity. However, due to these issues, when raw material quality and production management efforts fall short, electricity consumption can reach as high as 18,000 to 20,000 kW·h / t, resulting in persistently high energy costs for yellow phosphorus production. Summary of the Invention

[0005] In view of the problems in the prior art such as the decreasing inventory of high-grade and high-quality natural phosphate ore and the increasing demand for yellow phosphorus, and the instability of the yellow phosphorus production charge in the prior art (e.g., high carbonate content), which leads to high production energy consumption and affects product quality and yield, the present invention proposes a composite charge for yellow phosphorus smelting and a preparation method thereof. By combining waste phosphate rock powder generated during the mining and processing of raw phosphate ore with ash from the yellow phosphorus production process for pelletizing and sintering, artificial phosphate ore pellets that meet the requirements of yellow phosphorus production are obtained, thereby greatly improving the utilization efficiency of phosphorus resources and alleviating the pressure on the raw material demand for yellow phosphorus production. At the same time, by pre-thermal decomposition of raw phosphate ore to obtain decarbonized phosphorus ore, the decarbonized phosphorus ore is combined with the artificial phosphate ore pellets as the yellow phosphorus production charge, thereby reducing the carbonate content of the charge and ensuring the stability of the charge acidity, thereby significantly reducing the charge pulverization rate and greatly reducing energy consumption, and achieving significant economic benefits.

[0006] In order to achieve the above technical objectives, the technical solutions adopted by the present invention are specifically described as follows:

[0007] According to a first embodiment of the present invention, a composite charge for yellow phosphorus smelting is provided:

[0008] A composite charge for yellow phosphorus smelting, comprising artificial phosphate ore pellets, decarbonized phosphorus agglomerates, and coke. The artificial phosphate ore pellets comprise phosphate rock powder, phosphorus-containing ash, and flux, while the decarbonized phosphorus agglomerates are obtained by heat-treating natural phosphorus agglomerates to completely remove carbon or partially remove carbonates.

[0009] Preferably, the mixing mass ratio of the artificial phosphate ore pellets, decarbonized phosphate ore and coke is 30-80:20-70:11-17, preferably 35-75:25-65:12-16, and more preferably 40-70:30-60:13-15.

[0010] Preferably, the phosphate rock powder comprises one or more of fine ore produced during the mining and processing of raw phosphate ore, fine ore obtained by directly crushing raw phosphate ore, and fine particles produced during the sintering of artificial phosphate ore pellets. The phosphorus-containing ash comprises yellow phosphorus production dust and / or sludge phosphate slag. The flux is silica.

[0011] Preferably, the mixing mass ratio of the phosphate rock powder, the phosphorus-containing ash slag and the flux is 100-400:0-10:0-30, preferably 100-350:0.3-8:0.3-20, and more preferably 100-300:0.5-6:0.5-15.

[0012] Preferably, the heat treatment is to thermally decompose the natural phosphate rock at a temperature not lower than 540°C, preferably at a temperature of 700-1200°C, and more preferably at a temperature of 850-1100°C.

[0013] Preferably, the carbonate content of the decarbonized phosphate ore is 0-4 wt%, preferably 0.2-2.5 wt%, and more preferably 0.5-2 wt%.

[0014] Preferably, the particle size of the composite charge is 8 to 50 mm, preferably 10 to 40 mm, and more preferably 15 to 30 mm.

[0015] Preferably, the water content of the composite charge is lower than 1 wt%, preferably lower than 0.8 wt%, and more preferably lower than 0.5 wt%.

[0016] Preferably, the acidity of the composite charge is not less than 0.80, preferably 0.80-0.90, more preferably 0.83-0.86.

[0017] Preferably, the carbonate content of the composite charge is lower than 3 wt%, preferably lower than 2 wt%, more preferably lower than 1 wt%.

[0018] According to a second embodiment of the present invention, a method for preparing a composite charge for yellow phosphorus smelting is provided:

[0019] A method for preparing a composite charge for yellow phosphorus smelting or a method for preparing the composite charge for yellow phosphorus smelting as described in the first embodiment, the method comprising the following steps:

[0020] 1) Collecting the fine ore produced during the mining and processing of raw phosphate ore to obtain phosphate rock powder and / or directly crushing the raw phosphate ore to obtain phosphate rock powder. Collecting the dust and / or muddy phosphorus slag produced during the production of yellow phosphorus to obtain phosphorus-containing ash slag.

[0021] 2) The phosphate rock powder, phosphorus-containing ash and flux are mixed and ground to obtain a pelletizing mixture, and then water is added to the pelletizing mixture to perform a pelletizing process and then sintering to obtain artificial phosphate rock pellets. The natural phosphate rock is heat-treated to obtain decarbonized phosphate rock.

[0022] 3) According to the acidity requirement of the furnace, artificial phosphate ore pellets, decarbonized phosphorus ore and coke are mixed in proportion to obtain a composite furnace charge.

[0023] Preferably, in step 2), the natural phosphate ore is a mixed phosphate ore with a high carbonate content, and its carbonate content is not less than 3%, preferably not less than 5%, and more preferably not less than 8%.

[0024] Preferably, in step 2), the mass ratio of the phosphate rock powder, the phosphorus-containing ash, and the flux is 100-400:0-10:0-30, preferably 100-350:0.3-8:0.3-20, and more preferably 100-300:0.5-6:0.5-15. The average particle size of the pelletizing mixture is less than 0.5 mm, preferably less than 0.2 mm, and more preferably less than 0.1 mm. The pelletizing mixture has a ballability index of not less than 0.35, preferably not less than 0.6, and more preferably not less than 0.8.

[0025] Preferably, in step 2), the phosphate rock powder is set to be a mixed phosphate rock powder composed of n kinds of phosphate-containing phosphate rock powders, where n≥1. The ball-forming index of the pelletizing mixture is set to K, then:

[0026] K=(W 1-f ×X1+W 2-f ×X2+...+W n-f ×X n +W h-f ×X h +W r-f ×X r ) / [(W 1-m ×X1+W 2-m ×X2+...+W n-m ×X n +W

[0027] h-m ×X h +W r-m ×X r )-(W 1-f ×X1+W 2-f ×X2+...+W n-f ×X n +W h-f ×X h +W r-f ×X r )]

[0028] Among them, W 1-f To W n-f W is the mass proportion of the largest molecular water in each type of phosphorus-containing rock powder, %. 1-m To W n-m is the mass ratio of the maximum capillary water in various phosphate rock powders, %. X1 to X n is the proportion of various mineral powders, %. W h-f W is the mass proportion of the largest molecular water in phosphorus-containing ash, %. h-m is the mass ratio of the maximum capillary water in the phosphorus-containing ash, %. h W is the ratio of phosphorus-containing ash, %. r-f W is the mass proportion of the largest water molecule in the flux, %.r-m is the mass ratio of the maximum capillary water in the flux, %. r is the ratio of flux, %.

[0029] Preferably, in step 3), the mixing mass ratio of the artificial phosphate ore pellets, decarbonized phosphate briquette ore and coke is 30-80:20-70:11-17, preferably 35-75:25-65:12-16, and more preferably 40-70:30-60:13-15. The particle size of the composite charge is 8-50 mm, preferably 10-40 mm, and more preferably 15-30 mm. The water content of the composite charge is lower than 1 wt%, preferably lower than 0.8 wt%, and more preferably lower than 0.5 wt%. The acidity of the composite charge is not lower than 0.80, preferably 0.80-0.90, and more preferably 0.83-0.86. The carbonate content of the composite charge is lower than 3 wt%, preferably lower than 2 wt%, and more preferably lower than 1 wt%. The carbonate content of the decarbonized phosphate briquette ore is 0-4 wt%, preferably 0.2-2.5 wt%, and more preferably 0.5-2 wt%.

[0030] Preferably, in step 3), the acidity of the composite charge is set to A, then:

[0031] A=(W q-sd ×M q +W t-sd ×M t ) / (W q-co ×M q +W t-co ×M t )

[0032] Among them, W q-sd W is the mass percentage of SiO2 in artificial phosphate pellets, %. q-co is the mass proportion of CaO in artificial phosphate rock pellets, %. M q W is the mass percentage of artificial phosphate rock pellets, %. t-sd W is the mass percentage of SiO2 in decarbonized phosphate ore, %. t-co is the mass proportion of CaO in decarbonized phosphate ore, %. M t is the mass percentage of decarbonized phosphate ore, %.

[0033] Preferably, in step 2), the sintering temperature is 600-1300°C, preferably 700-1200°C, more preferably 800-1100°C.

[0034] Preferably, in step 2), the temperature of the heat treatment is not less than 540°C, preferably 700-1200°C, more preferably 850-1100°C.

[0035] Preferably, the flux is silica. The heat treatment is to use natural phosphate rock as a base material for sintering.

[0036] In the prior art, in order to improve the strength of artificial raw agglomerates or finished agglomerates prepared from waste phosphate rock powder (generally with a particle size of less than 5 mm) to meet the requirements of yellow phosphorus production and transportation, the prior art solutions often require the addition of various binders and additives (such as sodium humate, inorganic acids, etc.). The cost of the binders is relatively high. In addition, the small amount of binder used makes it difficult to mix the materials evenly, the pelletizing quality is unstable, and the pelletizing rate is not high. Therefore, the amount of binder used is generally relatively large, which further depletes the grade of the phosphate rock. Furthermore, the binder is not heat-resistant and pulverizes during the yellow phosphorus production process, making it unsuitable for pelletizing phosphate rock powder with high ignition loss. In addition, different ore powders have large differences in their adaptability to binders, making them not widely applicable. At the same time, the prior art solutions also fail to solve the problem of additional heat consumption caused by the high carbonate content in the natural agglomerates currently used in yellow phosphorus smelting, and the acidity adjustment operation of adding flux to the charge is not optimized, resulting in high power consumption in the electric furnace.

[0037] In the present invention, based on the full and efficient utilization of phosphate rock, the optimization of charge acidity adjustment and the energy saving and consumption reduction of electric furnaces, a composite charge for yellow phosphorus smelting and a preparation method thereof are proposed. The composite charge is mainly composed of artificial phosphate ore pellets and decarbonized phosphorus lump ore. Among them, artificial phosphate ore pellets are mainly prepared from various phosphate rock powders, yellow phosphorus production ash and flux and other raw materials generated during the mining and processing of phosphate ore, which improves the utilization efficiency of phosphorus resources and solves the problems of large-scale accumulation of waste phosphate rock powder causing waste of land resources and pollution to the environment. The decarbonized phosphate block ore is mainly obtained by removing (or partially removing) carbonates from natural phosphate block ore through high-temperature heat treatment (the heat treatment includes but is not limited to using natural phosphate block ore as a base material in the sintering process for preparing artificial phosphate ore pellets). By removing carbonates in advance, the absorption of heat by carbonates in the yellow phosphorus production furnace and the phenomenon of pulverization of the charge are avoided, thereby improving product quality and reducing production energy consumption. That is, it solves the problems of high powder ore yield that cannot be utilized in the current phosphate ore mining and utilization process, high additional heat consumption for decomposition of carbonates in phosphate block ore, and unstable adjustment of charge acidity. It should be noted that the amount of decarbonized phosphorus ore added to the composite charge should not be too high or too low. If the amount added is too low, the overall carbonate content of the composite charge will be relatively high, which is not conducive to production. If the amount added is too large, the amount of green pellets added to the furnace will be reduced, affecting production.

[0038] The composite furnace charge of the present invention has the characteristics of a better particle size range and precise control of the lower limit of particle size. The natural lump ore used in the existing technology for producing yellow phosphorus is generally screened to a lower limit of 5mm or even 4mm after drying. However, due to the low screening efficiency, the phosphate ore entering the electric furnace contains a certain amount of powder less than 5mm. The presence of this powder deteriorates the permeability of the furnace charge. The composite furnace charge provided by the present invention is composed of artificial phosphate ore pellets and decarbonized lump ore. Its minimum particle size can be increased to 8mm to 12mm, thereby significantly improving the permeability of the charge column in the electric furnace and the efficiency of phosphorus vapor rise.

[0039] In the present invention, the composite furnace charge of the present invention also has the characteristics of lower moisture and carbonate content and low thermal pulverization rate. Although the natural lump ore used in the existing technology for producing yellow phosphorus is provided with a drying link before entering the furnace, the moisture removal of the lump ore after drying is often not thorough due to factors such as process, equipment, and crystallization water. The evaporation of moisture in the furnace charge and the decomposition of carbonates in the electric furnace will consume additional heat, increasing the power consumption of the electric furnace. In addition, carbonate decomposition and thermal stress cause the lump ore to be easily pulverized in the high temperature zone, thereby deteriorating the permeability of the material column. The composite furnace charge provided by the present invention is prepared in advance through a high-temperature process. The artificial phosphate ore pellets and decarbonized phosphate lump ore are completely dehydrated and completely or partially decarbonized at high temperatures. Therefore, no additional heat is consumed after entering the electric furnace; and the damage caused by carbonate decomposition and thermal stress is released during the high-temperature process. At the same time, the powder produced is removed in advance during the preparation process, and no large amount of pulverization is produced after entering the electric furnace, thereby ensuring the permeability of the material column in the electric furnace.

[0040] In the present invention, phosphate rock powder includes phosphate rock powder produced from different ore mining processes, and can also be obtained by crushing and screening raw phosphate ore obtained from mining, for example, crushing and screening raw phosphate ore to obtain fine-grained phosphate ore, and then further grinding the fine-grained phosphate ore to obtain the target phosphate rock powder. It should be noted that the raw phosphate ore used for crushing and grinding to obtain phosphate rock powder is preferably selected from an ore with a low carbonate content; for raw phosphate ore with a high carbonate content, it is generally crushed to a particle size of Xmm to 50mm (fine-grained phosphate ore with a particle size <Xmm is ground into phosphate rock powder), where X generally has a minimum value of 12≥X≥8 (the minimum for natural phosphate rock lump ore), and its specific value is determined based on the ore's own properties such as hardness and wear resistance, and the requirements of the yellow phosphorus electric furnace for the permeability of the material column. Phosphate ore with a low carbonate content is crushed and ground to produce phosphate rock powder. Phosphate ore with a high carbonate content is crushed into larger-sized lumps. Heat treatment (including use as a sintering base) removes as much carbonate from the lumps as possible, thereby reducing the carbonate content in the composite furnace charge. This method allows for full utilization of mined ore, eliminating the accumulation of fine ore, and maximizing the efficiency of phosphorus resource utilization.

[0041] In the present invention, phosphate rock powder, ash from a yellow phosphorus production plant, flux and other materials are blended and mixed, and then ground together with the product undersize material returned from a back-end sintering process to obtain a pelletizing raw material with a particle size of less than 0.5 mm (preferably less than 0.2 mm, more preferably less than 0.1 mm). The resulting finely ground mixture is pelletized by adding water in a disc to obtain large-particle-size artificial phosphate rock green balls. Among them, the types and sources of phosphate rock powder are diverse, and can be either fine ore produced during the ore mining process or specially designated purchased (other production areas) phosphate rock blocks with a particle size greater than 5 mm or phosphate rock powder with a particle size less than 5 mm; the plant ash includes dust ash from yellow phosphorus production, mud phosphorus recovery slag, etc., and the flux includes silica, etc.; the mixing mass ratio of the flux is 100-400:0-10:0-30; the ratio of the plant ash is determined by its actual production amount (for the purpose of achieving its complete disposal). In addition, in the present invention, the ratio of various materials in the pelletizing mixture should also satisfy the pelletizing index K of the pelletizing mixture>0.35, and K is calculated by the following formula:

[0042] K=(W 1-f ×X1+W 2-f ×X2+...+W n-f ×X n +W h-f ×X h +W r-f ×X r ) / [(W 1-m ×X1+W 2-m ×X2+...+W n-m ×X n +W

[0043] h-m ×X h +W r-m ×X r )-(W 1-f ×X1+W 2-f ×X2+...+W n-f ×X n +W h-f ×X h +W r-f ×X r )]

[0044] Among them, W 1-f To W n-f W is the mass proportion of the largest molecular water in each type of phosphorus-containing rock powder, %. 1-m To W n-m is the mass ratio of the maximum capillary water in various phosphate rock powders, %. X1 to X n is the proportion of various mineral powders, %. W h-f W is the mass proportion of the largest molecular water in phosphorus-containing ash, %. h-mis the mass ratio of the maximum capillary water in the phosphorus-containing ash, %. h W is the ratio of phosphorus-containing ash, %. r-f W is the mass proportion of the largest water molecule in the flux, %. r-m is the mass ratio of the maximum capillary water in the flux, %. r is the ratio of flux, %. That is to say, the present invention utilizes the composite ore blending principle during pelletizing, utilizes the differences in pelletizing properties of phosphate rock and various materials to control the pelletizing properties of the pelletizing materials, and does not require the use of a binder.

[0045] In the present invention, according to experimental data, the ballability index K classification of the finely ground mixture of phosphate rock pelletizing and its corresponding relationship with the drop strength and compressive strength of phosphate rock green balls are shown in the following table:

[0046]

[0047] By adjusting the ball-forming index of the pelletizing mixture, it is possible to obtain phosphate ore green balls that meet the production process requirements without using a binder. In special circumstances, when the ball-forming index of the original phosphate rock powder, yellow phosphorus production ash, flux and other materials does not meet the requirements, it is possible to add specific purchased phosphate rock or phosphate rock powder with a high ball-forming index (K>0.6) after fine grinding to ensure that the pelletizing mixture can be formed into balls without a binder under any conditions and the quality meets the requirements. At the same time, by adjusting the ratio of each material and regulating the acidity value of the phosphate ore pellets, the acidity of the composite furnace charge is adjusted to a range suitable for electric furnace smelting, achieving the purpose of pre-setting the charge acidity adjustment operation during electric furnace smelting of yellow phosphorus.

[0048] In the present invention, in a preferred embodiment, raw phosphate ore with a high carbonate content and artificial phosphate ore green balls are placed on a chain roasting device and dried, roasted and cooled in sequence, wherein the carbonate in the raw phosphate ore is thermally decomposed and decarbonized to obtain decarbonized phosphate agglomerates, and the artificial phosphate ore green balls are consolidated at high temperature to obtain artificial phosphate ore pellets. During the placement, the raw phosphate ore and the green balls are loaded in order, with the raw phosphate ore placed on the lower layer (as a base material) and the green balls placed on the upper layer. The placement amount of the upper and lower material layers is generally M q :M t=30-80%:20-70%; the drying-roasting section uses exhaust ventilation, with a hood temperature of 130°C-1200°C. The cooling section uses exhaust or forced air cooling, with the cooling exhaust gas returned to the hoods of the roasting and drying sections, depending on the temperature. During the simultaneous roasting of artificial phosphate ore green pellets and raw phosphate ore, in addition to a small amount of pellet breakage, the raw phosphate ore also undergoes partial fragmentation due to the high temperature and carbonate decomposition. Therefore, the roasted material requires screening to remove fine ore (which can be recycled for pelletizing) and ensure the lower limit of the composite charge particle size. This is equivalent to pre-powdering the phosphate ore at high temperature in the electric furnace before the composite charge preparation process and removing it through screening. This reduces the amount of powder generated during the electric furnace smelting process and improves the permeability of the charge column. The present invention utilizes the waste heat discharged from the upper material layer to heat the phosphate ore used as the base material when the phosphate ore green pellets are subjected to high-temperature consolidation. The carbonate in the phosphate ore is thermally decomposed, thereby achieving the purpose of removing or partially removing the carbonate in the phosphate ore. At the same time, the heat absorption of the phosphate ore reduces the exhaust gas temperature at the lower part of the material layer, prevents the bottom temperature of the roasting device from overheating, reduces the equipment material requirements, and saves investment. It should be noted that the high-temperature decarbonization treatment of the phosphate ore can also be carried out using a separate heat treatment equipment. However, in the present invention, the pretreatment of the two raw materials of the composite furnace charge can be achieved through one process (sintering process), which saves energy consumption while reducing equipment investment and site occupation, and can significantly improve production efficiency.

[0049] In the present invention, the acidity of the phosphate ore pellets is regulated by adjusting the ratio of the various materials during the preparation process, so that the acidity of the composite charge reaches a range suitable for electric furnace smelting, thereby achieving the purpose of pre-setting the charge acidity adjustment operation during electric furnace smelting of yellow phosphorus. The mixed mass ratio of artificial phosphate ore pellets, decarbonized phosphorus lump ore, and coke in the composite charge is 30-80:20-70:11-17; in addition, the ratio of the various materials in the composite charge must also satisfy the composite charge acidity A ≥ 0.7, where A is calculated by the following formula:

[0050] A=(W q-sd ×M q +W t-sd ×M t ) / (W q-co ×M q +W t-co ×M t )

[0051] Among them, W q-sd W is the mass percentage of SiO2 in artificial phosphate pellets, %. q-co is the mass proportion of CaO in artificial phosphate rock pellets, %. M q W is the mass percentage of artificial phosphate rock pellets, %. t-sd W is the mass percentage of SiO2 in decarbonized phosphate ore, %.t-co is the mass proportion of CaO in decarbonized phosphate ore, %. M t is the mass percentage of decarbonized phosphate ore, %. The mass proportion of SiO2 in the artificial phosphate ore pellets and the mass proportion of CaO are calculated based on the mass proportion of SiO2 and CaO in each raw material in the pelletizing mixture and the proportion of each raw material. The composite furnace charge of the present invention mainly includes artificial phosphate ore pellets and decarbonized phosphate ore. Compared with the natural phosphate ore lump ore currently used in yellow phosphorus production, the composite furnace charge has an improved lower limit of particle size and does not contain -5mm powder, which is beneficial to the permeability of the electric furnace charge column and the prevention of arching and collapse; the moisture and carbonate content are low, which is beneficial to energy saving of the electric furnace; the acidity (SiO2 / CaO) meets the smelting requirements, and no flux needs to be added, thereby optimizing the smelting ingredients.

[0052] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0053] 1: The composite charge for yellow phosphorus smelting provided by the present invention has a better particle size range, a larger lower limit of particle size, and almost no -5mm powder; it has lower moisture and carbonate contents, a low thermal pulverization rate, and can reduce electric furnace energy consumption and the risk of arching and collapse; it has appropriate acidity and can be directly mixed with coke for smelting and use, thereby optimizing the charge structure and charge system.

[0054] 2: The composite charge for yellow phosphorus smelting and the preparation method of the present invention can be used to design a utilization plan starting from ore mining. Lump ore and powder ore are pretreated separately and then roasted simultaneously to obtain a composite phosphorus-containing charge. This can achieve full utilization of the ore, completely solve the problem of powder ore accumulation in mines, and maximize the efficiency of phosphorus resource utilization.

[0055] 3: The preparation method of the composite charge for yellow phosphorus smelting of the present invention utilizes the differences in the physical and chemical properties of various materials such as phosphate rock, and adjusts the ratio of each material to achieve the ball-forming property of the fine abrasive meeting the requirements, and no binder is required for ball-forming. By adjusting the acidity of the phosphate rock pellets, the acidity of the composite phosphorus-containing charge meets the furnace feeding requirements, and no additional flux is required during furnace smelting.

[0056] 4: The preparation method of the composite charge for yellow phosphorus smelting of the present invention realizes the simultaneous roasting of pellets and decarburization of phosphate ore lump by adjusting the distribution mode. At the same time, the phosphate ore lump can protect the lower layer from being too high, reducing the material requirements of the equipment. The thermal pulverization stage of the phosphate ore is also advanced through the synchronous roasting process, and the powder is removed by screening, thereby eliminating the thermal pulverization of the phosphate ore in the electric furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 The present invention is a process flow chart of the method for preparing a composite furnace charge for yellow phosphorus smelting. DETAILED DESCRIPTION

[0058] The technical solutions of the present invention are illustrated below with examples, and the scope of protection requested by the present invention includes but is not limited to the following embodiments.

[0059] Example 1

[0060] Various phosphate rock ores mined from different phosphate mines are crushed and sieved to obtain various phosphate lumps with a particle size of 10 mm to 40 mm and various fine-grained phosphate powder ores with a particle size of less than 10 mm; the various fine-grained phosphate powder ores are then mixed and further crushed and ground to 150 mesh to obtain mixed phosphate rock powder (the ball formation index of which is detected to be approximately 0.53); the mixed phosphate rock powder is then added with water to form balls in a disc to obtain phosphate rock green balls with a diameter of 10 mm to 40 mm.

[0061] The phosphate ore with high carbonate content (carbonate content 8.4%) and phosphate ore green balls are loaded into the chain roasting device in sequence. The phosphate ore is placed on the lower layer and the phosphate ore green balls are placed on the upper layer. The amount of the lower and upper layers is M t :M q =35%:65%, and then dried at 150℃, roasted at 1100℃ and cooled by exhaust. The cooling exhaust gas is returned to the smoke hood of the roasting section and the drying section according to the temperature, to obtain artificial phosphate ore pellets and decarbonized phosphate ore (carbonate content is about 3.9%).

[0062] Artificial phosphate ore pellets with a particle size of all greater than 10 mm (the roasted material less than 10 mm is returned and mixed with fine-grained phosphate ore for grinding) are mixed with decarbonized phosphate lump ore and coke in a mass ratio of 60:40:15 to obtain a composite furnace charge (the acidity of which was detected to be approximately 0.81, the moisture content was approximately 0.15wt%, and the carbonate content was approximately 1.6wt%).

[0063] Example 2

[0064] The mixed phosphate rock powder obtained in Example 1 was mixed with the collected yellow phosphorus production phosphorus-containing ash in a mass ratio of 100:6 to obtain a pelletizing mixture (the pelletizing index of which was detected to be approximately 0.62); the pelletizing mixture was pelletized by adding water in a disc to obtain phosphate rock green balls with a diameter of 10 mm to 40 mm.

[0065] Phosphate ore with a carbonate content of about 8.4% and phosphate ore green balls are mixed in a mass ratio of M t :M q =35%:65% are successively distributed to the chain roasting device, and are dried at 150°C, roasted at 1100°C and cooled by exhaust to obtain artificial phosphate ore pellets and decarbonized phosphate ore (carbonate content is about 3.5%).

[0066] Artificial phosphate ore pellets with a particle size of more than 10 mm were mixed with decarbonized phosphate ore and coke in a mass ratio of 60:40:15 to obtain a composite furnace charge (the acidity was detected to be about 0.82, the moisture content was about 0.12wt%, and the carbonate content was about 1.5wt%).

[0067] Example 3

[0068] The mixed phosphate rock powder obtained in Example 1 was mixed with the collected yellow phosphorus production phosphorus-containing ash and silica powder in a mass ratio of 100:6:10 to obtain a pelletizing mixture (the pelletizing index of which was detected to be approximately 0.73); the pelletizing mixture was added with water in a disc to obtain phosphate rock green balls with a diameter of 10 mm to 40 mm.

[0069] Phosphate ore with a carbonate content of about 8.4% and phosphate ore green balls are mixed in a mass ratio of M t :M q =35%:65% are successively distributed to the chain roasting device, and are dried at 150°C, roasted at 1100°C and cooled by exhaust to obtain artificial phosphate ore pellets and decarbonized phosphate ore (carbonate content is about 3.3%).

[0070] Artificial phosphate ore pellets with a particle size of >10 mm were mixed with decarbonized phosphate ore and coke in a mass ratio of 60:40:15 to obtain a composite furnace charge (the acidity was detected to be about 0.86, the moisture content was about 0.11wt%, and the carbonate content was about 1.4wt%).

[0071] Example 4

[0072] Example 3 was repeated except that the phosphate ore with a carbonate content of about 8.4% was replaced with a phosphate ore with a carbonate content of 4.1%.

[0073] Example 5

[0074] Example 3 was repeated except that the phosphate ore with a carbonate content of about 8.4% was replaced with a phosphate ore with a carbonate content of 11.9%.

[0075] Example 6

[0076] Example 4 was repeated, except that the mixing ratio of the various fine-grained phosphate rocks was adjusted so that the final pelletizing mixture had a pelletizing index of 0.85.

[0077] Example 7

[0078] Example 3 was repeated except that the mass ratio of the mixed phosphate rock powder, yellow phosphorus production phosphorus-containing ash, and silica powder was 100:14:10.

[0079] Example 8

[0080] Example 3 was repeated except that the mass ratio of phosphate rock powder, yellow phosphorus production phosphorus-containing ash, and silica powder was 100:6:40.

[0081] Comparative Example 1

[0082] The various phosphate ores obtained in Example 3 were mixed and dried to obtain a finished phosphate ores. The finished phosphate ores were mixed with silica and coke in a mass ratio of 100:30:16 to obtain a composite furnace charge.

[0083] Comparative Example 2

[0084] Bentonite was added as a binder to the mixed phosphate rock powder obtained in Example 3 to obtain a pelletizing mixture, and the pelletizing mixture was pelletized by adding water in a disc to obtain phosphate rock green balls with a diameter of 10 mm to 40 mm (due to the use of a binder, the production cost was increased and the phosphorus grade of the pellets was reduced).

[0085] The phosphate rock pellets are placed on a chain roasting device, dried at 150°C, roasted at 1100°C, and cooled by ventilation to obtain roasted pellets. The roasted pellets are then mixed with silica and coke in a mass ratio of 100:5:15 to obtain a composite furnace charge.

[0086] Comparative Example 3

[0087] Comparative Example 2 was repeated, except that the acid slag, an intermediate product of the dihydrate wet-process phosphoric acid production, was used as a binder (the use of the binder increased production costs and reduced the phosphorus grade of the pellets).

[0088] The phosphate ore pellets and composite furnace charges prepared in Examples 1-8 and Comparative Examples 1-3 were tested, and the results are shown in the following table:

[0089]

[0090]

[0091] The furnace materials obtained in Examples 1-8 and Comparative Examples 1-3 (all with particle sizes greater than 10 mm) were fed into an electric furnace to produce phosphorus. The parameters are compared in the following table:

[0092]

Claims

1. A composite charge for yellow phosphorus smelting, characterized by: The composite furnace charge includes artificial phosphate ore pellets, decarbonized phosphorus ore and coke; wherein: the artificial phosphate ore pellets include phosphate rock powder, phosphorus-containing ash and flux, and the decarbonized phosphorus ore is obtained by heat-treating natural phosphorus ore to completely remove carbon or partially remove carbonate.

2. The composite charge according to claim 1, characterized in that: The mixing mass ratio of the artificial phosphate ore pellets, decarbonized phosphate ore and coke is 30-80:20-70:11-17, preferably 35-75:25-65:12-16, and more preferably 40-70:30-60:13-15.

3. The composite charge according to claim 1 or 2, characterized in that: The phosphate rock powder includes one or more of the following: powdered ore produced during the mining and processing of raw phosphate ore, powdered ore obtained by directly crushing raw phosphate ore, and fine particles produced during the sintering of artificial phosphate ore pellets; the phosphorus-containing ash includes dust removed from yellow phosphorus production and / or muddy phosphorus slag; and the flux is silica. Preferably, the mixing mass ratio of the phosphate rock powder, the phosphorus-containing ash slag and the flux is 100-400:0-10:0-30, preferably 100-350:0.3-8:0.3-20, and more preferably 100-300:0.5-6:0.5-15.

4. The composite charge according to any one of claims 1 to 3, characterized in that: The heat treatment is to perform thermal decomposition treatment on the natural phosphate rock at a temperature of not less than 540°C, preferably at a temperature of 700-1200°C, and more preferably at a temperature of 850-1100°C; Preferably, the carbonate content of the decarbonized phosphate ore is 0-4 wt%, preferably 0.2-2.5 wt%, and more preferably 0.5-2 wt%.

5. The composite charge according to any one of claims 1 to 4, characterized in that: The particle size of the composite charge is 8 to 50 mm, preferably 10 to 40 mm, more preferably 15 to 30 mm; and / or The water content of the composite charge is lower than 1 wt%, preferably lower than 0.8 wt%, more preferably lower than 0.5 wt%; and / or The acidity of the composite charge is not less than 0.80, preferably 0.80-0.90, more preferably 0.83-0.86; and / or The carbonate content of the composite charge is lower than 3 wt %, preferably lower than 2 wt %, and more preferably lower than 1 wt %.

6. A method for preparing a composite charge for yellow phosphorus smelting or a method for preparing the composite charge for yellow phosphorus smelting according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: 1) collecting the fine ore produced during the mining and processing of raw phosphate ore to obtain phosphate rock powder and / or directly crushing the raw phosphate ore to obtain phosphate rock powder; collecting the dust and / or mud phosphorus produced during the production of yellow phosphorus to obtain phosphorus-containing ash slag; 2) mixing and grinding phosphate rock powder, phosphorus-containing ash, and flux to obtain a pelletizing mixture, adding water to the pelletizing mixture to perform a pelletizing process, and then sintering the mixture to obtain artificial phosphate rock pellets; and heat-treating natural phosphate rock to obtain decarbonized phosphate rock. 3) According to the acidity requirement of the furnace, artificial phosphate ore pellets, decarbonized phosphorus ore and coke are mixed in proportion to obtain a composite furnace charge.

7. The method according to claim 6, characterized in that: In step 1) and in step 2), the natural phosphate ore is a mixed phosphate ore with a high carbonate content, and its carbonate content is not less than 3%, preferably not less than 5%, and more preferably not less than 8%.

8. The method according to claim 6 or 7, characterized in that: In step 2), the mixing mass ratio of the phosphate rock powder, the phosphorus-containing ash, and the flux is 100-400:0-10:0-30, preferably 100-350:0.3-8:0.3-20, and more preferably 100-300:0.5-6:0.5-15; the average particle size of the pelletizing mixture is less than 3 mm, preferably less than 1 mm, and more preferably less than 0.5 mm; the pelletizing index of the pelletizing mixture is not less than 0.35, preferably not less than 0.6, and more preferably not less than 0.8; Preferably, the phosphate rock powder is set to be a mixed phosphate rock powder composed of n kinds of phosphate-containing phosphate rock powders, n ≥ 1; and the ball-forming index of the ball-forming mixture is set to K, then: K=(W 1-f ×X1+W 2-f ×X2+...+W n-f ×X n +W h-f ×X h +W r-f ×X r ) / [(W 1-m ×X1+W 2-m ×X2+...+W n-m ×X n +W h-m ×X h +W r-m ×X r )-(IN 1-f ×X1+W 2-f ×X2+...+W n-f ×X n +W h-f ×X h +W r-f ×X r )] Among them, W 1-f To W n-f W is the mass proportion of the largest molecular water in various phosphorus-containing rock powders, %; 1-m To W n-m is the mass ratio of the maximum capillary water in various phosphate-containing rock powders, %; X1 to X n is the ratio of various mineral powders, %; W h-f W is the mass proportion of the largest molecular water in phosphorus-containing ash, %; h-m is the mass ratio of the maximum capillary water in the phosphorus-containing ash, %; X h is the ratio of phosphorus-containing ash, %; W r-f is the mass proportion of the largest molecule water in the flux, %; W r-m is the mass ratio of the maximum capillary water in the flux, %; X r is the ratio of flux, %.

9. The method according to any one of claims 6 to 8, characterized in that: In step 3), the mixing mass ratio of the artificial phosphate ore pellets, the decarbonized phosphate briquette ore, and the coke is 30-80:20-70:11-17, preferably 35-75:25-65:12-16, and more preferably 40-70:30-60:13-15; the particle size of the composite charge is 8-50 mm, preferably 10-40 mm, and more preferably 15-30 mm; the water content of the composite charge is less than 1 wt%, preferably less than 0.8 wt%, and more preferably less than 0.5 wt%; the acidity of the composite charge is not less than 0.80, preferably 0.80-0.90, and more preferably 0.83-0.86; the carbonate content of the composite charge is less than 3 wt%, preferably less than 2 wt%, and more preferably less than 1 wt%; the carbonate content of the decarbonized phosphate briquette ore is 0-4 wt%, preferably 0.2-2.5 wt%, and more preferably 0.5-2 wt% Preferably, the acidity of the composite charge is set to A, then: A=(W q-sd ×M q +W t-sd ×M t ) / (W q-co ×M q +W t-co ×M t ) Among them, W q-sd is the mass proportion of SiO2 in artificial phosphate pellets, %; W q-co is the mass proportion of CaO in artificial phosphate pellets, %; M q is the mass percentage of artificial phosphate ore pellets, %; W t-sd is the mass proportion of SiO2 in decarbonized phosphate ore, %; W t-co is the mass proportion of CaO in decarbonized phosphate ore, %; M t is the mass percentage of decarbonized phosphate ore, %.

10. The method according to any one of claims 6 to 9, characterized in that: In step 2), the sintering temperature is 600-1300° C., preferably 700-1200° C., more preferably 800-1100° C.; and / or In step 2), the heat treatment temperature is not less than 540°C, preferably 700-1200°C, more preferably 850-1100°C; preferably, the flux is silica; and the heat treatment is to use natural phosphate rock as a base material for sintering treatment.

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