A slag removal agent for improving slag making and slag removal efficiency in industrial silicon smelting and a preparation method thereof

Abstract

The present invention provides a slag removal agent for improving the slag removal efficiency of industrial silicon smelting and a preparation method thereof. The slag removal agent comprises the following main ingredients in a weight ratio: calcium oxide and carbonaceous powder = 1-3: 1-3. The preparation method of the slag removal agent is characterized in that the calcium oxide is first crushed to a particle size of ≤3 mm for standby use, NaOH and a curing agent are respectively prepared into a 25-50% NaOH solution and a 1.1-2.1% curing agent solution, and the two are mixed evenly, and then the crushed calcium oxide is added to a mixture of charcoal powder, petroleum coke powder and dry powder binder, and then fully stirred in a silo, and the material enters a ball pressing system under its own gravity and is cold pressed into a pellet and dried. The carbon and calcium pellets provided by the present invention replace the large-particle limestone in the traditional process, and the slag removal effect is significantly improved compared with the traditional method. The slag production rate is increased from 10.04% to 12.94%, an increase of 2.9 percentage points. Due to the good slag removal effect in the furnace and the improved furnace condition, the output is significantly increased, and the average daily output is increased from 49.399 tons / day to 51.822 tons / day, an increase of 2.423 tons.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial silicon smelting, and particularly relates to a slag removal agent for improving the slag making and slag removal efficiency of industrial silicon smelting and a preparation method thereof. Background Art

[0002] Industrial silicon is a product obtained by high-temperature reduction and smelting in a submerged arc furnace using silica as raw material and carbonaceous raw material as reducing agent. In the process of industrial silicon smelting, commonly used reducing agents include charcoal, petroleum coke, and washed coal. Charcoal has been used as the preferred reducing agent for industrial silicon smelting because of its high fixed carbon, high specific resistivity, and low impurity content. However, due to the influence of ecological environmental protection policies, charcoal production is prohibited. Industrial silicon production enterprises can only explore and use non-wood reducing agents for smelting production. However, with the increase in the amount of coal coke, the impurities such as aluminum and calcium brought in also increase. During the smelting process, unreduced SiC and oxides such as SiO2, CaO, and Al2O3 form semi-melts. These melts not only have high melting points, but also have high viscosity and poor fluidity. They are not easy to be discharged from the furnace when they are discharged from the furnace, and accumulate at the bottom of the furnace, causing the slag at the bottom of the furnace to accumulate and rise, and the electrode is lifted up, the furnace condition deteriorates, and the output and quality are affected. The existing technology mainly adopts the method of adding limestone or calcium fluoride to clean the furnace. Specifically, limestone is added to the triangular area of ​​the electric furnace and the root of the electrode, and added 2-3 times before silicon is discharged. The amount of each addition is controlled at 400-500kg, and the total amount of limestone or calcium fluoride added is controlled at 1-1.5 tons. It can be seen that the amount of slag removal agent added before each furnace of silicon is discharged is large, the cost is high, and it needs to be added in 3 times, which is a lot of work.

[0003] Therefore, how to effectively improve the slag removal efficiency through reasonable and effective slag removal agents and furnace washing methods is a technical problem that industrial silicon production enterprises need to solve urgently in order to increase production, quality and efficiency. Summary of the invention

[0004] The first object of the present invention is to provide a slag removal agent for improving the slag making and slag removal efficiency of industrial silicon smelting. The second object of the present invention is to provide a preparation method of the slag removal agent. The third object of the present invention is a method for industrial silicon smelting using the slag removal agent.

[0005] The first object of the present invention is achieved in this way: a slag removal agent for improving the slag making and slag removal efficiency of industrial silicon smelting, characterized in that it includes the following main ingredients in a weight ratio: calcium oxide and carbonaceous powder = 1~3:1~3.

[0006] The second object of the present invention is achieved in this way. The preparation method of the slag removal agent is as follows: first, the calcium oxide is crushed to a particle size of ≤3mm for standby use, and then NaOH and a curing agent are respectively prepared into a 25-50% NaOH solution and a 1.1-2.1% curing agent solution, and then mixed and added to a mixture of the crushed calcium oxide and charcoal powder, petroleum coke powder and dry powder binder, and then the material is fully stirred in the silo and enters the ball pressing system under the action of its own gravity, and then cold pressed into a ball and dried.

[0007] The third purpose of the present invention is achieved in this way. A method for smelting industrial silicon is to add the slag removal agent to the triangle area of ​​the electric furnace and / or the bottom of the electrode 2 hours before the next furnace of silicon is discharged according to the slag removal cycle, and the additional amount each time is controlled at 300-600kg, and the total amount added each time the furnace is washed is controlled at 0.8-1 ton.

[0008] The main component of the slag-making agent used in the present invention is calcium oxide. The main difference from the prior art is that the calcium exists in a different form. The calcium used in the prior art exists in the form of calcium carbonate (CaCO3), with a relatively low calcium content of 35-40% and a particle size of 20-50 mm. The calcium used in the slag-making agent of the present invention exists in the form of calcium oxide (CaO), with a relatively high calcium content of 58-60%, and is a granular material less than 3 mm. The alkaline calcium oxide combines with the acidic oxides SiO2 and Al2O3 with higher melting points in the sticky slag to form a slag with a low melting point and good fluidity. Due to the increase in the amount of slag and the improvement of its fluidity, the slag is easily discharged from the furnace. Charcoal powder and petroleum coke powder reduce SiO2, Al2O3 and CaO in the slag, which is beneficial to reducing the amount of slag on the one hand, and on the other hand, it helps to reduce the viscosity of the slag and quickly remove the slag.

[0009] The beneficial effects of the present invention are:

[0010] 1) The present invention utilizes the characteristics of carbonate with low melting point and good fluidity, and adopts carbon and calcium pellets as slag removal agents for the first time. Compared with the prior art, it has three advantages: First, the calcium content of the calcium oxide used is relatively high, which can reduce the amount of slag-making agent added during a single furnace washing and slag removal, and reduce the labor intensity of employees; second, the calcium oxide is pre-crushed into small particles of less than 3 mm. Compared with the prior art adding 20-50 mm limestone, the reaction speed is fast and the reaction time is short, which ensures that the slag-making agent fully reacts with the molten slag in a relatively short time, providing an important guarantee for improving the slag removal efficiency. Third, compared with the single addition of calcium slag-making agent, carbon and calcium pellets add a reducing agent, which not only destroys the slag, but also provides a reducing agent for the unreacted oxides in the slag. The oxides in the slag can be effectively reduced, which provides a guarantee for further improving the fluidity of the slag and reducing the amount of slag.

[0011] 2) The present invention adopts carbon calcium slag agent for slag removal, which solves the problems of high slag melting point, high viscosity and increased trace elements leading to reduced product quality caused by the large amount of coal coke used in industrial silicon smelting, realizes high-coal coke industrial silicon smelting production, and achieves a major breakthrough in the traditional silicon smelting charcoal operation technology.

[0012] 3) The carbon and calcium pellet deslagging agent provided by the present invention replaces the large-particle limestone in the traditional process. The charge has good air permeability, and the calcium content of the deslagging agent is higher than that of the traditional deslagging agent. The deslagging effect is significantly improved compared with the traditional deslagging method. The slag production rate is increased from 10.04% to 12.94%, an increase of 2.9 percentage points. Due to the good deslagging effect in the furnace and the improvement of the furnace condition, the output is significantly increased. The average daily output is increased from 49.399 tons / day to 51.822 tons / day, an increase of 2.423 tons. DETAILED DESCRIPTION

[0013] The present invention is further described below in conjunction with the embodiments, but the present invention is not limited in any way. Any changes or improvements made based on the teachings of the present invention belong to the protection scope of the present invention.

[0014] The invention discloses a slag removal agent for improving the slag making and slag removal efficiency of industrial silicon smelting. The slag removal agent comprises the following main materials in a weight ratio: the weight ratio of calcium oxide to carbonaceous powder is 1-3:1-3.

[0015] The carbonaceous powder comprises the following components in weight ratio: the weight ratio of charcoal powder to petroleum coke powder is 0.5-2:0.5-1.

[0016] The deslagging agent also includes the following auxiliary materials: dry powder binder, NaOH and curing agent.

[0017] The weights of the dry powder binder, NaOH and curing agent are 7-9%, 1.2-1.6% and 0.05-0.07% of the total weight of the main material respectively.

[0018] The dry powder binder is commercially available GY dry powder binder.

[0019] The curing agent is a curing agent used in combination with a GY dry powder binder.

[0020] The present invention also provides a preparation method of the slag removal agent, which is specifically as follows: firstly crushing the calcium oxide to a particle size of ≤3 mm for standby use, then preparing NaOH and a curing agent into a 25-50% NaOH solution and a 1.1-2.1% curing agent solution respectively, mixing them, adding them to a mixture of the crushed calcium oxide and charcoal powder, petroleum coke powder and dry powder binder, and mixing them evenly, then fully stirring the materials in a silo, and entering a ball pressing system under the action of their own gravity, and then cold pressing them into balls and drying them.

[0021] The dimensions of the pellets are length: width: thickness = 70-90mm: 40-60mm: 30-40mm, and the pressure of the pellet pressing system is 10-15MPa.

[0022] The present invention further provides a method for smelting industrial silicon, which is to add the deslagging agent to the electric furnace triangle area and / or the bottom of the electrode 2 hours before the next furnace of silicon is discharged according to the deslagging cycle, and the additional amount each time is controlled at 300-600kg, and the added amount is controlled at 0.8-1 ton.

[0023] The slag removal cycle is 7-15 days.

[0024] The present invention will be further described below with reference to the embodiments.

[0025] Example 1

[0026] A method for preparing a slag removal agent for improving the slag removal efficiency of industrial silicon smelting, the specific steps are as follows: 500kg of calcium oxide is crushed into particles with a particle size of 3mm, 250kg of charcoal powder, and 250kg of petroleum coke powder are mixed evenly, and 70kg of GY coal pellet dry powder binder is added and mixed to obtain a mixture. 12kg of NaOH and 0.5kg of curing agent are weighed and respectively configured into a 25% NaOH solution and a 1.1% curing agent solution. The NaOH solution and the curing agent solution are mixed and added to the mixture, and sent to a silo for sufficient stirring. Finally, after entering the ball pressing system, they are cold pressed into 90mm:40mm:40mm pellets at a pressure of 10MPa, and air-dried to obtain the target slag removal agent.

[0027] Every 7 days, 800 kg of the above deslagging agent is added twice to the triangular area of ​​the electric furnace and / or the bottom of the electrode 2 hours before silicon is discharged to wash the furnace and deslagging.

[0028] Results: Slag discharge was smooth, and the slag production rate increased from 10.04% to 12.94%, an increase of 2.9 percentage points. Due to the good slag discharge effect in the furnace and the improvement of furnace conditions, the output was significantly increased. The average daily output increased from 49.399 tons / day to 51.822 tons / day, an increase of 2.423 tons.

[0029] Example 2

[0030] A method for preparing a slag removal agent for improving the slag removal efficiency of industrial silicon smelting, the specific steps are as follows: 500kg of calcium oxide is crushed into particles with a particle size of 2mm, 500kg of charcoal powder, and 500kg of petroleum coke powder are mixed evenly, and 120kg of GY coal pellet dry powder binder is added and mixed to obtain a mixture. 22kg of NaOH and 0.9kg of curing agent are weighed and respectively configured into a 40% NaOH solution and a 1.6% curing agent solution. The NaOH solution and the curing agent solution are mixed and added to the mixture, and sent to a silo for sufficient stirring. Finally, after entering the ball pressing system, they are cold pressed into 80mm:50mm:35mm pellets at a pressure of 15MPa, and air-dried to obtain the target slag removal agent.

[0031] Every 10 days, 100 kg of the above deslagging agent is added twice to the triangular area of ​​the electric furnace and / or the bottom of the electrode 2 hours before silicon discharge to wash the furnace and deslagging.

[0032] Results: Slag discharge was smooth, and the slag production rate increased from 10.04% to 12.77%, an increase of 2.7 percentage points. Due to the good slag discharge effect in the furnace and the improved furnace condition, the output was significantly increased. The average daily output increased from 49.399 tons / day to 51.299 tons / day, an increase of 1.9 tons.

[0033] Example 3

[0034] A method for preparing a slag removal agent for improving the slag removal efficiency of industrial silicon smelting, the specific steps are as follows: 500kg of calcium oxide is crushed into particles with a particle size of 3mm, 1000kg of charcoal powder, and 350kg of petroleum coke powder are mixed evenly, and 167kg of GY coal pellet dry powder binder is added and mixed to obtain a mixture. 29.5kg of NaOH and 1.2kg of curing agent are weighed and respectively configured into 50% NaOH solution and 2.1% curing agent solution. The NaOH solution and the curing agent solution are mixed and added to the mixture, and sent to the silo for sufficient stirring, and finally enter the ball pressing system and cold pressed into 80mm:60mm:40mm pellets at a pressure of 12MPa, and air-dried to obtain the target slag removal agent.

[0035] Two hours before silicon is discharged, 900 kg of the above deslagging agent is added three times to the triangular area of ​​the electric furnace and / or the bottom of the electrode to wash the furnace and deslagging.

[0036] Results: Slag discharge was smooth, and the slag production rate increased from 10.04% to 12.81%, an increase of 2.8 percentage points. Due to the good slag discharge effect in the furnace and the improved furnace condition, the output was significantly increased. The average daily output increased from 49.399 tons / day to 51.482 tons / day, an increase of 2.083 tons.

[0037] Example 4

[0038] A method for preparing a slag removal agent for improving the slag removal efficiency of industrial silicon smelting, the specific steps are as follows: 500kg of calcium oxide is crushed into particles with a particle size of 2.5mm, 250kg of blue carbon powder, and 500kg of coke powder are mixed evenly, and 100kg of GY coal pellet dry powder binder is added, and mixed to obtain a mixture. 18.75kg of NaOH and 0.8kg of curing agent are weighed and respectively configured into a 35% NaOH solution and a 1.8% curing agent solution. The NaOH solution and the curing agent solution are mixed and added to the mixture, and sent to the silo for sufficient stirring, and finally enter the ball pressing system and cold pressed into 70mm:60mm:30mm pellets at a pressure of 11MPa, and air-dried to obtain the target slag removal agent.

[0039] Every 7 days, 800 kg of the above deslagging agent is added twice to the triangular area of ​​the electric furnace and / or the bottom of the electrode 2 hours before silicon is discharged to wash the furnace and deslagging.

[0040] Results: Slag discharge was smooth, and the slag production rate increased from 10.04% to 12.36%, an increase of 2.3 percentage points. Due to the good slag discharge effect in the furnace and the improved furnace condition, the output was significantly increased. The average daily output increased from 49.399 tons / day to 51.617 tons / day, an increase of 2.218 tons.

[0041] Example 5

[0042] A method for preparing a slag removal agent for improving the slag removal efficiency of industrial silicon smelting, the specific steps are as follows: 500kg of calcium oxide is crushed into particles with a particle size of 2.5mm, 500kg of charcoal powder, and 250kg of coke powder are mixed evenly, and 115kg of GY coal pellet dry powder binder is added and mixed to obtain a mixture. 18kg of NaOH and 0.8kg of curing agent are weighed and respectively configured into a 40% NaOH solution and a 1.8% curing agent solution. The NaOH solution and the curing agent solution are mixed and added to the mixture, and sent to a silo for sufficient stirring. Finally, after entering the ball pressing system, they are cold pressed into 80mm:50mm:35mm pellets at a pressure of 14MPa, and air-dried to obtain the target slag removal agent.

[0043] Every 7 days, 100 kg of the above deslagging agent is added 3 times to the triangular area of ​​the electric furnace and / or the bottom of the electrode 2 hours before silicon discharge to wash the furnace and deslagging.

[0044] Results: Slag discharge was smooth, and the slag production rate increased from 10.04% to 12.11%, an increase of 2.1 percentage points. Due to the good slag discharge effect in the furnace and the improvement of furnace conditions, the output was significantly increased. The average daily output increased from 49.399 tons / day to 51.327 tons / day, an increase of 1.928 tons.

Claims

1. A slag removal agent for improving the slag making and slag removal efficiency of industrial silicon smelting, characterized in that: The deslagging agent comprises a main material and an auxiliary material; the main material is composed of calcium oxide and carbonaceous powder in a weight ratio of 1-3:1-3, wherein the crushed particle size of calcium oxide is ≤3 mm, and the carbonaceous powder is composed of charcoal powder and petroleum coke powder in a weight ratio of 0.5-2:0.5-1; the auxiliary material comprises a dry powder binder, NaOH, and a curing agent, wherein the weight of the dry powder binder, NaOH, and the curing agent is 7-9%, 1.2-1.6%, and 0.05-0.07% of the total weight of the main material, respectively; the dry powder binder is a commercially available GY dry powder binder, and the curing agent is a curing agent used in combination with the GY dry powder binder; the preparation method of the deslagging agent is firstly The calcium oxide is crushed to a particle size of ≤3mm, and the crushed calcium oxide is evenly mixed with charcoal powder and petroleum coke powder according to a ratio, and a dry powder binder is added and mixed to obtain a mixture; NaOH and a curing agent are respectively prepared into a 25-50wt% NaOH solution and a 1.1-2.1wt% curing agent solution and mixed, and then added into the mixture according to a ratio and fully stirred in a silo; the material enters a ball pressing system under the action of its own gravity, and is cold pressed at a pressure of 10-15MPa to form a pellet with a length, width and thickness of 70-90mm, 40-60mm and 30-40mm respectively, and the pellet is dried to obtain the deslagging agent.

2. A method for smelting industrial silicon, characterized in that: According to the deslagging cycle, 2 hours before the next silicon is discharged from the furnace, the deslagging agent according to claim 1 is added to the electric furnace triangle area and / or the bottom of the electrode in 2 or 3 times, with the amount added each time controlled at 300-600 kg and the total amount added controlled at 0.8-1 ton.

3. The smelting method according to claim 2, characterized in that: The slag discharge cycle is 7 to 15 days.