Method for slowing down the formation of rings in the production of basic pellets in a grate-kiln

Abstract

The application discloses a method for slowing down the ring coking of alkaline pellet in a chain grate-rotary kiln production, which comprises the following steps: weighing and proportioning 70-100 parts of limestone powder, 890-920 parts of iron ore powder and 10 parts of bentonite; mixing the limestone powder, the iron ore powder and the bentonite in a mixer, adding water in a disc pelletizer to pelletize; distributing, drying and preheating the pellets on a chain grate-rotary kiln roasting device to obtain preheated pellets; and continuously roasting the preheated pellets in a rotary kiln after the preheated pellets are discharged from the head of the chain grate to obtain finished pellets, wherein the rotary kiln refractory material comprises the following components: MgO>50%, Cr2O3>20%, SiO2<3% and (K2O+Na2O)<0.5%. By adjusting the rotary kiln refractory material from mainly containing Al2O3 and SiO2 to mainly containing MgO and Cr2O3, the application slows down the formation speed of the ring coking material and effectively improves the production efficiency of the alkaline pellet.

Description

Technical Field

[0001] This invention belongs to the field of alkaline pellet production technology, and more specifically relates to a method for slowing down ring formation in alkaline pellet production using a chain grate-rotary kiln. Background Technology

[0002] Basic iron ore pellets are characterized by their good reducing properties, making them a high-quality raw material for blast furnaces. Most domestic and international companies produce basic iron ore pellets primarily using a belt roaster process. This process is characterized by high single-unit capacity, high production efficiency, and the absence of the ring-forming problem common in rotary kilns. However, the extensive use of high-temperature heat-resistant steel in the equipment leads to relatively high investment costs, and the requirement for gaseous fuel results in high operating costs for companies without access to inexpensive gas sources. Therefore, some companies have adopted a chain grate-rotary kiln process for producing basic iron ore pellets. This process is characterized by relatively lower investment costs and the ability to use pulverized coal as fuel, resulting in lower operating costs. However, the biggest challenge is the tendency for ring-forming in the rotary kiln during production, especially when the iron ore powder used has a high SiO2 content, making the production of high-basicity basic iron ore pellets more difficult. When using the chain grate-rotary kiln process to produce acidic pellets, the ring-forming cycle of the rotary kiln can reach 50-60 days, meaning that the rotary kiln only needs to deal with the rings once after 50-60 days of continuous production. However, when using the chain grate-rotary kiln process to produce basic pellets, the ring-forming cycle of the rotary kiln is only 20-25 days. The production cycle is short, half that of producing acidic pellets. Therefore, the kiln must be stopped frequently during the production process to deal with the rings, which seriously affects the production efficiency of basic pellets. Summary of the Invention

[0003] To address the technical problems existing in the prior art, the present invention provides a method for mitigating ring formation in the production of alkaline pellets using a chain grate-rotary kiln, comprising the following steps:

[0004] (1) Ingredients

[0005] Iron ore powder, limestone powder, and bentonite are weighed and mixed according to the following weight proportions: 70-100 parts limestone powder, 890-920 parts iron ore powder, and 10 parts bentonite.

[0006] (2) Mixing and pelletizing

[0007] The above-mentioned limestone powder, iron ore powder and bentonite are mixed evenly by a mixer, and then added to a disc pelletizer to make pellets by adding water.

[0008] (3) Preheating

[0009] The pellets are fed, dried, and preheated on a chain grate-rotary kiln calcining equipment to obtain preheated pellets.

[0010] (4) Roasting

[0011] The preheated pellets enter the rotary kiln from the machine head of the chain grate machine, and are continuously high-temperature baked to obtain finished pellets, wherein the rotary kiln head temperature is controlled to be 1160-1180℃, the rotary kiln tail hot air temperature is controlled to be 900-950℃, and the rotary kiln refractory material composition is controlled to be: MgO>50%, Cr2O3>20%, SiO2<3%, (K2O+Na2O)<0.5%.

[0012] Further, in the method for reducing the ring formation of the alkaline pellets produced by the chain grate-rotary kiln, the iron grade of the iron ore powder is 65.2%, and the SiO2 content is 4.5%; the CaO content in the limestone powder is 52.4%.

[0013] Further, in the method for reducing the ring formation of the alkaline pellets produced by the chain grate-rotary kiln, the moisture content of the pellets produced by the mixing and balling is 9.8% by weight, and the average particle size of the pellets is controlled to be 8-16 mm.

[0014] Further, in the method for reducing the ring formation of the alkaline pellets produced by the chain grate-rotary kiln, the binary basicity of the finished alkaline pellets is 1.1.

[0015] As a specific embodiment, in the method for reducing the ring formation of the alkaline pellets produced by the chain grate-rotary kiln, the main components of the rotary kiln refractory material are controlled to be: MgO=51.3%, Cr2O3=20.7%, SiO2=2.8%, (K2O+Na2O)=0.45%.

[0016] As a specific embodiment, in the method for reducing the ring formation of the alkaline pellets produced by the chain grate-rotary kiln, the main components of the rotary kiln refractory material are controlled to be: MgO=54.2%, Cr2O3=20.7%, SiO2=2.8%, (K2O+Na2O)=0.45%.

[0017] As a specific embodiment, in the method for reducing the ring formation of the alkaline pellets produced by the chain grate-rotary kiln, the main components of the rotary kiln refractory material are controlled to be: MgO=57.3%, Cr2O3=20.7%, SiO2=2.8%, (K2O+Na2O)=0.45%.

[0018] As a specific embodiment, in the method for reducing the ring formation of the alkaline pellets produced by the chain grate-rotary kiln, the main components of the rotary kiln refractory material are controlled to be: MgO=51.3%, Cr2O3=23.5%, SiO2=2.8%, (K2O+Na2O)=0.45%.

[0019] As a specific embodiment, in the method for reducing the ring formation of the basic pellet produced by the chain-grate machine-rotary kiln, the main components of the rotary kiln refractory material are controlled as follows: MgO=51.3%, Cr2O3=26.7%, SiO2=2.8%, (K2O+Na2O)=0.45%.

[0020] As a specific embodiment, in the method for reducing the ring formation of the basic pellet produced by the chain-grate machine-rotary kiln, the main components of the rotary kiln refractory material are controlled as follows: MgO=51.3%, Cr2O3=28.2%, SiO2=2.8%, (K2O+Na2O)=0.45%.

[0021] The method for reducing the ring formation of the basic pellet produced by the chain-grate machine-rotary kiln has the following advantages and beneficial effects:

[0022] By adjusting the main components of the rotary kiln refractory material of the chain-grate machine-rotary kiln production line from Al2O3 and SiO2 to MgO and Cr2O3, the formation speed of the ring formation material in the process of producing the basic pellet by the chain-grate machine-rotary kiln is reduced, the production cycle of the chain-grate machine-rotary kiln for producing the basic pellet is extended to more than 30 days on average, the frequency of shutdown caused by the ring formation of the rotary kiln is significantly reduced, the production efficiency of the basic pellet is effectively improved, powerful technical support is provided for realizing the continuous production of the basic pellet by the chain-grate machine-rotary kiln, and good popularization value and economic benefits are obtained. DETAILED DESCRIPTION

[0023] To make the objectives, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described clearly and completely below in combination with specific embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0024] The present application aims to reduce the ring formation of the basic pellet produced by the chain-grate machine-rotary kiln, effectively improve the production efficiency of the chain-grate machine-rotary kiln production line, reduce the frequency of shutdown caused by the ring formation of the rotary kiln, and ensure the smooth production of the basic pellet. To this end, the present application provides a method for reducing the ring formation of the basic pellet produced by the chain-grate machine-rotary kiln, and the main technical idea is to adjust the main components of the rotary kiln refractory material of the chain-grate machine-rotary kiln production line from Al2O3 and SiO2 to MgO and Cr2O3. Through this technical measure, the formation speed of the ring formation material in the process of producing the basic pellet by the chain-grate machine-rotary kiln can be effectively reduced, the problem of ring formation in the production of the basic pellet by the chain-grate machine-rotary kiln is solved, and the production efficiency of the basic pellet is improved.

[0025] Specifically, the method for slowing down the ring formation of alkaline pellets produced by a chain grate-rotary kiln of the present application comprises the following steps:

[0026] (1) batching

[0027] The iron ore powder, limestone powder and bentonite are weighed and batched according to the following weight fractions: 70-100 parts of limestone powder, 890-920 parts of iron ore powder, and 10 parts of bentonite, wherein the iron ore powder is Shanxi Lanxian iron ore powder with an iron grade of 65.2% and a SiO2 content of 4.5%, the CaO content in the limestone powder is 52.4%, and the bentonite is a conventional bentonite purchased on the market.

[0028] (2) mixing and balling

[0029] The above limestone powder, iron ore powder and bentonite are mixed uniformly by a mixer, and then added to a disc balling machine for water addition and balling to produce pellets with a moisture content of 9.8% by weight, and the average particle size of the pellets is controlled to be 8-16 mm.

[0030] (3) preheating

[0031] The pellets are distributed, dried and preheated on a chain grate-rotary kiln roasting device to obtain preheated pellets.

[0032] (4) roasting

[0033] The preheated pellets are introduced into the rotary kiln from the head of the chain grate, and continue to be roasted at high temperature to obtain finished pellets, wherein the rotary kiln head temperature is controlled to be 1160-1180℃, the rotary kiln tail hot air temperature is controlled to be 900-950℃, the binary basicity (CaO / SiO2) of the finished pellet is controlled to be 1.1, and the composition of the rotary kiln refractory material is controlled to be: MgO > 50%, Cr2O3 > 20%, SiO2 < 3%, (K2O + Na2O) < 0.5%.

[0034] The method for slowing down the ring formation of alkaline pellets produced by a chain grate-rotary kiln of the present application is further described below in combination with a reference example in the prior art and an embodiment of the present application.

[0035] Reference Example

[0036] The reference example is a conventional method for producing alkaline pellets by a chain grate-rotary kiln process, and the specific production steps are as follows:

[0037] (1) batching

[0038] The limestone powder, iron ore powder and bentonite are mixed uniformly by a mixer, and then added into a disc balling machine to make balls with water supplement, to produce the ball with a water content of 9.8% by weight percentage, and the average particle size of the ball is 8-16 mm.

[0039] (2) Mixing and balling

[0040] The limestone powder, iron ore powder and bentonite are mixed uniformly by a mixer, and then added into a disc balling machine to make balls with water supplement, to produce the ball with a water content of 9.8% by weight percentage, and the average particle size of the ball is 8-16 mm.

[0041] (3) Preheating

[0042] The ball is distributed, dried and preheated on a chain grate-rotary kiln roasting device, to obtain preheated ball.

[0043] (4) Roasting

[0044] The preheated ball is put into the rotary kiln from the head of the chain grate, and is continuously roasted at high temperature to obtain the finished ball, wherein the temperature of the rotary kiln head is 1160-1180℃, the hot air temperature of the rotary kiln tail is 900-950℃, the binary basicity of the finished ball is 1.1, and the main components of the rotary kiln refractory material are: Al2O3=78.3%, SiO2=15%, CaO=1.1%, (K2O+Na2O)=0.68%.

[0045] According to actual calculation, in the reference example, the kiln needs to be stopped for processing the ring-forming material in the kiln for an average of 23 days. The above reference example shows that when the basicity ball is roasted, the rotary kiln is prone to ring formation, and the kiln needs to be stopped for processing the ring-forming material for an average of 23 days. The ring-forming material is formed at a fast speed, and the production cycle is short, which leads to low production efficiency of the basicity ball produced by the chain grate-rotary kiln in the conventional process.

[0046] Example 1

[0047] In the example 1 of the present application, the main components of the rotary kiln refractory material of the chain grate-rotary kiln production line are adjusted from Al2O3 and SiO2 to MgO and Cr2O3. Specifically, the method for slowing down the ring formation of the basicity ball produced by the chain grate-rotary kiln in the example 1 comprises the following steps:

[0048] (1) Proportioning

[0049] The iron ore powder, limestone powder and bentonite are weighed and proportioned according to the following weight parts: 94 parts of limestone powder, 896 parts of iron ore powder and 10 parts of bentonite, wherein the iron ore powder is Shanxi Lanxian iron ore powder with an iron grade of 65.2% and a SiO2 content of 4.5%, the limestone powder has a CaO content of 52.4%, and the bentonite is a conventional bentonite purchased on the market.

[0050] (2) Mixing and balling

[0051] The limestone powder, iron ore powder and bentonite are mixed uniformly in a mixer, and then water is added for balling in a disc balling machine to produce pellets with a water content of 9.8% by weight, and the average particle size of the pellets is 8-16 mm.

[0052] (3) Preheating

[0053] The pellets are distributed, dried and preheated on a grate-kiln roasting device to obtain preheated pellets.

[0054] (4) Roasting

[0055] The preheated pellets are introduced into a rotary kiln from the head of the grate, and are continuously roasted at high temperature to obtain finished pellets, wherein the rotary kiln head temperature is 1160-1180℃, the rotary kiln tail hot air temperature is 900-950℃, the binary basicity of the finished pellet is 1.1, and the main components of the rotary kiln refractory material are: MgO=51.3%, Cr2O3=20.7%, SiO2=2.8%, (K2O+Na2O)=0.45%.

[0056] According to actual calculation, in the embodiment 1 of the present application, the kiln needs to be stopped for processing the ring-forming material in the kiln for an average of 29 days. The above embodiment 1 shows that, after using the new refractory material to replace the original refractory material, the kiln needs to be stopped for processing the ring-forming material in the kiln for an average of 29 days, compared with the reference embodiment in the prior art, the production cycle of the grate-kiln for producing basic pellets is prolonged by 6 days, and the production efficiency of the basic pellets is effectively improved.

[0057] Embodiment 2

[0058] In the embodiment 2 of the present application, the MgO content ratio in the rotary kiln refractory material of the grate-kiln production line is increased from 51.3% in the embodiment 1 to 54.2%, and the remaining main components Cr2O3, SiO2 and K2O+Na2O have the same content as in the embodiment 1. Specifically, the method for slowing down the ring-forming of the grate-kiln for producing basic pellets in the embodiment 2 comprises the following steps:

[0059] (1) Proportioning

[0060] The iron ore powder, limestone powder and bentonite are weighed and proportioned according to the following weight parts: 94 parts of limestone powder, 896 parts of iron ore powder and 10 parts of bentonite, wherein the iron ore powder is Shanxi Lanxian iron ore powder with an iron grade of 65.2% and a SiO2 content of 4.5%, the limestone powder has a CaO content of 52.4%, and the bentonite is a conventional bentonite purchased on the market.

[0061] (2) Mixing and balling

[0062] The limestone powder, iron ore powder and bentonite are mixed uniformly in a mixer, and then water is added to the disc balling machine for balling, so that the produced pellets have a water content of 9.8% by weight and an average particle size of 8-16 mm.

[0063] (3) Preheating

[0064] The pellets are distributed, dried and preheated on a chain grate-rotary kiln roasting device, and the preheated pellets are obtained.

[0065] (4) Roasting

[0066] The preheated pellets are introduced into the rotary kiln from the head of the chain grate, and are continuously roasted at high temperature, so that the finished pellets are obtained, wherein the rotary kiln head temperature is 1160-1180℃, the rotary kiln tail hot air temperature is 900-950℃, the binary basicity of the finished pellet is 1.1, and the main components of the rotary kiln refractory material are as follows: MgO=54.2%, Cr2O3=20.7%, SiO2=2.8%, (K2O+Na2O)=0.45%.

[0067] According to actual calculation, the rotary kiln needs to be stopped for processing the ring-forming material in the kiln for an average of 30 days in the embodiment 2. The above embodiment 2 shows that, by increasing the MgO content ratio in the refractory material from 51.3% in the embodiment 1 to 54.2%, the production cycle of the chain grate-rotary kiln for producing basic pellets is prolonged by 1 day compared with the embodiment 1, and is prolonged by 7 days compared with the baseline embodiment in the prior art, thereby effectively improving the production efficiency of the basic pellets.

[0068] Embodiment 3

[0069] In the embodiment 3 of the present application, the MgO content ratio in the refractory material of the rotary kiln of the chain grate-rotary kiln production line is increased from 54.2% in the embodiment 2 to 57.3%, and the remaining main components Cr2O3, SiO2 and K2O+Na2O have the same content as in the embodiment 2. Specifically, the method for slowing down the ring-forming of the basic pellets in the chain grate-rotary kiln of the embodiment 3 comprises the following steps:

[0070] (1) Proportioning

[0071] The iron ore powder, limestone powder and bentonite are weighed and proportioned according to the following weight fractions: 94 parts of limestone powder, 896 parts of iron ore powder and 10 parts of bentonite, wherein the iron ore powder is Shanxi Lanxian iron ore powder with an iron grade of 65.2% and a SiO2 content of 4.5%, the limestone powder has a CaO content of 52.4%, and the bentonite is a conventional bentonite purchased on the market.

[0072] (2) Mixing and balling

[0073] The limestone powder, iron ore powder and bentonite are mixed uniformly in a mixer, and then water is added for balling in a disc balling machine to produce pellets with a water content of 9.8% by weight, and the average particle size of the pellets is 8-16 mm.

[0074] (3) Preheating

[0075] The pellets are distributed, dried and preheated on a chain grate-rotary kiln roasting device to obtain preheated pellets.

[0076] (4) Roasting

[0077] The preheated pellets are introduced into the rotary kiln from the head of the chain grate, and are continuously roasted at high temperature to obtain finished pellets, wherein the rotary kiln head temperature is 1160-1180℃, the rotary kiln tail hot air temperature is 900-950℃, the binary basicity of the finished pellet is 1.1, and the main components of the rotary kiln refractory material are: MgO=57.3%, Cr2O3=20.7%, SiO2=2.8%, (K2O+Na2O)=0.45%.

[0078] According to actual calculation, in the embodiment 3, the average production cycle is 30.5 days, and the kiln needs to be stopped for processing the ring-forming material in the kiln. The above embodiment 3 shows that by increasing the MgO content ratio in the refractory material from 54.2% in embodiment 2 to 57.3%, the production cycle of the chain grate-rotary kiln for producing basic pellets is further prolonged by 0.5 days compared with embodiment 2, and is prolonged by 7.5 days compared with the benchmark embodiment in the prior art, thereby effectively improving the production efficiency of the basic pellets.

[0079] Embodiment 4

[0080] In the embodiment 4 of the present application, the Cr2O3 content ratio in the rotary kiln refractory material of the chain grate-rotary kiln production line is increased from 20.7% in embodiment 1 to 23.5%, and the remaining main components MgO, SiO2 and K2O+Na2O have the same content as in embodiment 1. Specifically, the method for slowing down the ring-forming of the basic pellets in the chain grate-rotary kiln of embodiment 4 comprises the following steps:

[0081] (1) Proportioning

[0082] The iron ore powder, limestone powder and bentonite are weighed and proportioned according to the following weight fractions: 94 parts of limestone powder, 896 parts of iron ore powder and 10 parts of bentonite, wherein the iron ore powder is Shanxi Lanxian iron ore powder with an iron grade of 65.2% and a SiO2 content of 4.5%, the limestone powder has a CaO content of 52.4%, and the bentonite is a conventional bentonite purchased on the market.

[0083] (2) Mixing and balling

[0084] The limestone powder, iron ore powder and bentonite are mixed uniformly in a mixer, and then water is added to the disc balling machine for balling, thereby producing pellets with a water content of 9.8% by weight, and an average particle size of 8-16 mm.

[0085] (3) Preheating

[0086] The pellets are distributed, dried and preheated on a chain grate-rotary kiln roasting device, and the preheated pellets are obtained after preheating.

[0087] (4) Roasting

[0088] The preheated pellets are introduced into the rotary kiln from the head of the chain grate, and are continuously roasted at high temperature, thereby obtaining finished pellets, wherein the rotary kiln head temperature is 1160-1180℃, the rotary kiln tail hot air temperature is 900-950℃, the binary basicity of the finished pellet is 1.1, and the main components of the rotary kiln refractory material are as follows: MgO=51.3%, Cr2O3=23.5%, SiO2=2.8%, (K2O+Na2O)=0.45%.

[0089] According to actual calculation, the rotary kiln needs to be stopped for processing the ring-forming material in the kiln for an average of 31 days in the embodiment 4. The above embodiment 4 shows that by increasing the Cr2O3 content ratio in the refractory material from 20.7% in the embodiment 1 to 23.5%, the production cycle of the chain grate-rotary kiln for producing basic pellets is further prolonged by 2 days compared with the embodiment 1, and is prolonged by 8 days compared with the benchmark embodiment in the prior art, thereby effectively improving the production efficiency of the basic pellets.

[0090] Embodiment 5

[0091] In the embodiment 5, the Cr2O3 content ratio in the refractory material of the rotary kiln of the chain grate-rotary kiln production line is increased from 23.5% in the embodiment 4 to 26.7%, and the contents of the remaining main components MgO, SiO2 and K2O+Na2O are the same as those in the embodiment 4. Specifically, the method for slowing down the ring-forming of the chain grate-rotary kiln for producing basic pellets in the embodiment 5 includes the following steps:

[0092] (1) Proportioning

[0093] The iron ore powder, limestone powder and bentonite are weighed and proportioned according to the following weight parts: 94 parts of limestone powder, 896 parts of iron ore powder and 10 parts of bentonite, wherein the iron ore powder is Shanxi Lanxian iron ore powder with an iron grade of 65.2% and a SiO2 content of 4.5%, the limestone powder has a CaO content of 52.4%, and the bentonite is a conventional bentonite purchased on the market.

[0094] (2) Mixing and balling

[0095] The limestone powder, iron ore powder and bentonite are mixed uniformly in a mixer, and then water is added to a disc balling machine for balling, so that the produced pellets have a water content of 9.8% by weight and an average particle size of 8-16 mm.

[0096] (3) Preheating

[0097] The pellets are distributed, dried and preheated on a chain grate-rotary kiln roasting device, and the preheated pellets are obtained.

[0098] (4) Roasting

[0099] The preheated pellets are introduced into a rotary kiln from the head of the chain grate, and are continuously roasted at high temperature, so that the finished pellets are obtained, wherein the rotary kiln head temperature is 1160-1180℃, the rotary kiln tail hot air temperature is 900-950℃, the binary basicity of the finished pellet is 1.1, and the main components of the rotary kiln refractory material are as follows: MgO=51.3%, Cr2O3=26.7%, SiO2=2.8%, (K2O+Na2O)=0.45%.

[0100] According to actual calculation, the rotary kiln needs to be stopped for processing the ring-forming material in the kiln for an average of 32 days in the embodiment 5. The above embodiment 5 shows that, by increasing the Cr2O3 content ratio in the refractory material from 23.5% in the embodiment 4 to 26.7%, the production cycle of the chain grate-rotary kiln for producing basic pellets is prolonged by 1 day compared with the embodiment 4, and is prolonged by 9 days compared with the benchmark embodiment in the prior art, thereby effectively improving the production efficiency of the basic pellets.

[0101] Embodiment 6

[0102] In the embodiment 6, the Cr2O3 content ratio in the refractory material of the rotary kiln of the chain grate-rotary kiln production line is increased from 26.7% in the embodiment 4 to 28.2%, and the contents of the main components MgO, SiO2 and K2O+Na2O are the same as those in the embodiment 5. Specifically, the method for slowing down the ring-forming of the chain grate-rotary kiln for producing basic pellets in the embodiment 6 includes the following steps:

[0103] (1) Proportioning

[0104] The limestone powder, iron ore powder and bentonite are weighed and mixed according to the following weight proportions: 94 parts of limestone powder, 896 parts of iron ore powder and 10 parts of bentonite, wherein the iron ore powder is Shanxi Lanxian iron ore powder with an iron grade of 65.2% and a SiO2 content of 4.5%, the limestone powder has a CaO content of 52.4%, and the bentonite is a conventional bentonite purchased on the market.

[0105] (2) Mixing and balling

[0106] The limestone powder, iron ore powder and bentonite are mixed in a mixer, and then water is added to a disc balling machine for balling, so that the produced pellets have a water content of 9.8% by weight and an average particle size of 8-16 mm.

[0107] (3) Preheating

[0108] The pellets are distributed, dried and preheated on a grate-kiln roasting device, and the preheated pellets are obtained after preheating.

[0109] (4) Roasting

[0110] The preheated pellets are introduced into a rotary kiln from the head of the grate, and are continuously high-temperature roasted to obtain finished pellets, wherein the rotary kiln head temperature is 1160-1180℃, the rotary kiln tail hot air temperature is 900-950℃, the binary basicity of the finished pellet is 1.1, and the main components of the rotary kiln refractory material are: MgO=51.3%, Cr2O3=28.2%, SiO2=2.8%, (K2O+Na2O)=0.45%.

[0111] According to actual calculation, the rotary kiln needs to be stopped for processing the ring-forming material in the kiln for an average of 32.5 days in the embodiment 6. The above embodiment 6 shows that by increasing the Cr2O3 content ratio in the refractory material from 26.7% in the embodiment 5 to 28.2%, the production cycle of the grate-kiln for producing basic pellets is prolonged by 0.5 days compared with the embodiment 5, and is prolonged by 9.5 days compared with the benchmark embodiment in the prior art, thereby effectively improving the production efficiency of the basic pellets.

[0112] To sum up, the method for slowing down the ring forming of the chain-grate machine-rotary kiln production of alkaline pellet by the application adjusts the refractory material of the rotary kiln of the chain-grate machine-rotary kiln production line from Al2O3 and SiO2 as the main components to MgO and Cr2O3 as the main components, slows down the forming speed of the ring forming material in the process of the chain-grate machine-rotary kiln production of alkaline pellet, and prolongs the production cycle of the chain-grate machine-rotary kiln production of alkaline pellet to more than 30 days on average, that is, by using the method for slowing down the ring forming of the chain-grate machine-rotary kiln production of alkaline pellet, the kiln needs to be stopped for processing the ring forming material in the kiln only after 30 days of average production, which is more than 7 days longer than the prior art, thereby significantly reducing the frequency of shutdown due to the ring forming of the rotary kiln, effectively improving the production efficiency of the alkaline pellet, providing strong technical support for realizing the continuous production of the alkaline pellet by the chain-grate machine-rotary kiln, and having good popularization value and economic benefits.

[0113] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the application, and not to limit them; although the application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: the technical solutions recorded in the foregoing examples can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the application.

Claims

1. A method for mitigating ring formation in the production of alkaline pellets using a chain grate-rotary kiln, characterized in that, Includes the following steps: (1) Ingredients Iron ore powder, limestone powder, and bentonite are weighed and mixed according to the following weight proportions: 70-100 parts limestone powder, 890-920 parts iron ore powder, and 10 parts bentonite. (2) Mixing and pelletizing The above-mentioned limestone powder, iron ore powder and bentonite are mixed evenly by a mixer, and then added to a disc pelletizer to make pellets by adding water. (3) Preheating The pellets are fed, dried, and preheated on a chain grate-rotary kiln calcining equipment to obtain preheated pellets. (4) Roasting After exiting the chain grate mill, the preheated pellets enter the rotary kiln for further high-temperature calcination to obtain the finished pellets. The temperature at the kiln head is controlled at 1160–1180℃, and the hot air temperature at the kiln tail is controlled at 900–950℃. The composition of the refractory material in the rotary kiln is controlled as follows: MgO > 50%, Cr2O3 > 20%, SiO2 < 3%, (K2O + Na2O) < 0.5%.

2. The method for mitigating ring formation in the production of alkaline pellets using a chain grate-rotary kiln according to claim 1, characterized in that, The iron ore powder has an iron grade of 65.2% and a SiO2 content of 4.5%; the limestone powder has a CaO content of 52.4%.

3. The method for mitigating ring formation in the production of alkaline pellets using a chain grate-rotary kiln according to claim 1, characterized in that, The pellets obtained from the mixing and pelletizing process have a moisture content of 9.8% by weight, and the average particle size of the pellets is controlled to be 8–16 mm.

4. The method for mitigating ring formation in the production of alkaline pellets using a chain grate-rotary kiln according to claim 1, characterized in that, The binary basicity of the finished alkaline pellets is 1.

1.

5. The method for mitigating ring formation in the production of alkaline pellets using a chain grate-rotary kiln according to claim 1, characterized in that, The main components of the rotary kiln refractory material are controlled as follows: MgO = 51.3%, Cr2O3 = 20.7%, SiO2 = 2.8%, (K2O + Na2O) = 0.45%.

6. The method for mitigating ring formation in the production of alkaline pellets using a chain grate-rotary kiln according to claim 1, characterized in that, The main components of the rotary kiln refractory material are controlled as follows: MgO = 54.2%, Cr2O3 = 20.7%, SiO2 = 2.8%, (K2O + Na2O) = 0.45%.

7. The method for mitigating ring formation in the production of alkaline pellets using a chain grate-rotary kiln according to claim 1, characterized in that, The main components of the rotary kiln refractory material are controlled as follows: MgO = 57.3%, Cr2O3 = 20.7%, SiO2 = 2.8%, (K2O + Na2O) = 0.45%.

8. The method for mitigating ring formation in the production of alkaline pellets using a chain grate-rotary kiln according to claim 1, characterized in that, The main components of the rotary kiln refractory material are controlled as follows: MgO = 51.3%, Cr2O3 = 23.5%, SiO2 = 2.8%, (K2O + Na2O) = 0.45%.

9. The method for mitigating ring formation in the production of alkaline pellets using a chain grate-rotary kiln according to claim 1, characterized in that, The main components of the rotary kiln refractory material are controlled as follows: MgO = 51.3%, Cr2O3 = 26.7%, SiO2 = 2.8%, (K2O + Na2O) = 0.45%.

10. The method for mitigating ring formation in the production of alkaline pellets using a chain grate-rotary kiln according to claim 1, characterized in that, The main components of the rotary kiln refractory material are controlled as follows: MgO = 51.3%, Cr2O3 = 28.2%, SiO2 = 2.8%, (K2O + Na2O) = 0.45%.