A method for upgrading semi-coke to prepare raw materials for injection and sintering

Abstract

The present invention discloses a method for upgrading semi-coke to prepare raw materials for injection and sintering, comprising the following steps: mixing and kneading semi-coke powder, high fixed-carbon powder, binder and upgrading improver to obtain shaped raw materials; pressing the shaped raw materials to form semi-coke pellets with regular shapes; carbonizing the semi-coke pellets to obtain upgraded semi-coke pellets; and crushing and screening the upgraded semi-coke pellets to obtain raw materials for injection and sintering. The present invention uses a combined process of shaping + carbonization to process semi-coke powder and produce high-quality upgraded carbon materials; after pyrolysis and upgrading, the volatile matter of the semi-coke powder in the present invention can be significantly reduced from the current 8-12% to less than 4.5%, which is a clean and pure carbon material raw material and can be used as raw materials for injection and sintering in steel production.

Description

Technical Field

[0001] The present invention belongs to the fields of injection and sintering raw material preparation in the iron and steel industry, and particularly relates to a method for upgrading semi-coke to prepare raw materials for injection and sintering. Background Art

[0002] In China, low-rank coals account for more than 57% of the total coal reserves. Using coal separation and utilization technology to convert low-rank coals into three different forms of energy, namely coal gas, tar, and semi-coke, is a very effective means of efficiently utilizing low-rank coals. Among them, semi-coke products, as a new type of carbon material, have the advantages of high fixed carbon, high chemical activity, high specific resistance, low ash content, low sulfur content, and low phosphorus content, and have been widely used in the calcium carbide and ferrosilicon industries. With the large-scale popularization of low-rank coal separation and utilization technology in recent years, it is urgent to seek new application markets for semi-coke to absorb the newly increased production capacity.

[0003] With the rapid development of China's iron and steel industry, the demand for high-quality anthracite and metallurgical coke fines in blast furnace injection and sintering is increasing continuously, making the scarcity of anthracite and coking coal increasingly prominent. Seeking high-quality alternative raw materials is imminent. Compared with anthracite and coke fines, semi-coke is superior to anthracite in combustion performance due to its high calorific value and non-explosive characteristics, and is a high-quality injection raw material; at the same time, it has the advantages of low ash content and low harmful elements S / P, and replacing metallurgical coke fines for sintering can improve the quality of sinter ore and reduce the concentration of pollutants in sintering flue gas.

[0004] At present, semi-coke production mainly uses medium and low-temperature pyrolysis. The hot semi-coke obtained by carbonization is cooled by water quenching and then screened. Finally, it is divided into several products according to particle size, namely large materials, medium and small materials, and semi-coke fines. Among them, large materials and medium and small materials are mainly used as raw materials for the production of calcium carbide and ferrosilicon, and semi-coke fines are used as raw materials for injection and sintering in the iron and steel industry. The particle size of semi-coke fines is generally 0-8 mm. When used for injection and sintering, it needs to be crushed and ground. However, due to its too low grindability index (HGI) (generally less than 45%) and too strong abrasiveness to equipment, the efficiency of the pulverizing system is greatly reduced and the pipeline wear is serious. Iron and steel enterprises can only meet the production volume and relieve wear by reducing the use ratio of semi-coke. At present, the proportion of semi-coke in the injection fuel of steel plants is generally only 10-15%, and most do not exceed 25%. The semi-coke fines obtained by medium and low-temperature pyrolysis have a high volatile content, generally about 8-12%, and there are problems such as poor air permeability in the sintering material layer when replacing metallurgical coke fines for sintering. Summary of the Invention

[0005] In order to solve the problems of poor grindability and high volatile content of semi-coke fines when used as raw materials for injection and sintering production, the present invention proposes a method for upgrading semi-coke to prepare raw materials for injection and sintering. This method can improve the grindability index of semi-coke, reduce its abrasiveness and volatile content, and can be used as raw materials for injection and sintering in iron and steel production.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A method for upgrading semi-coke to prepare raw materials for injection and sintering, comprising the following steps:

[0008] Mix and knead semi-coke powder, high fixed-carbon powder, binder and upgrading modifier to obtain shaped raw materials;

[0009] Press the shaped raw materials to form semi-coke pellets with regular shapes;

[0010] Carbonize the semi-coke pellets to obtain upgraded semi-coke pellets;

[0011] Crush and screen the upgraded semi-coke pellets to obtain raw materials for injection and sintering.

[0012] Further, the high fixed-carbon powder is one or more of anthracite, non-sticky bituminous coal, metallurgical coke powder, waste activated coke and waste activated carbon.

[0013] Further, the addition amount of the high fixed-carbon powder is 0-15% of the total weight of the shaped raw materials.

[0014] Further, the binder is one or several of starch, coal tar, caking coal fine powder, coal tar pitch and humic acid.

[0015] Further, the addition amount of the binder is 3-8% of the total weight of semi-coke and high fixed-carbon powder.

[0016] Further, the upgrading modifier is quicklime, slaked lime or lignin powder.

[0017] Further, the addition amount of the upgrading modifier is 0-8% of the total weight of semi-coke and high fixed-carbon powder.

[0018] Further, the pressure for pressing the shaped raw materials is 5-10 t / cm, and the outer shape of the semi-coke pellets is pillow-shaped, ellipsoidal or oval-shaped.

[0019] Further, the specific process of carbonizing the semi-coke pellets includes drying and dehydration, carbonization and cooling or includes drying and carbonization.

[0020] Further, the carbonization is carried out in one or more of the atmospheres of carbon monoxide, hydrogen and nitrogen; the carbonization temperature is 700-1000 °C, and the time is 2-6 h.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] The present invention uses a combined process of forming + carbonization to process semi-coke fines and produce high-quality upgraded carbon materials. During the forming process, the semi-coke fines are subjected to a pair-roll extrusion pressure of more than 200 - 500 tons. The high pressure can cause the semi-coke fines to be extruded against each other and further refined. At the same time, it can also cause the internal cracks of the semi-coke fines to expand and generate new micro-cracks, so as to reduce the anti-crushing strength of the semi-coke fines and increase its grindability index HGI. By adding high-fixed-carbon powder materials with good grindability, the grindability index of semi-coke can be increased. During the forming process, the upgrading and modifying agents are all soft and fine powders, which can coat and fill some sharp corners and cracks of the semi-coke, reducing its abrasiveness. The wear of the upgraded semi-coke pellets on the conveying equipment can be significantly improved, and its grindability index can also be increased by 6 - 12%. Due to the significant increase in the grindability index of the semi-coke after carbonization and upgrading, when using the undersize material after crushing and screening the upgraded pellets for grinding, the output of the pulverizing system can basically reach the level of anthracite, and thus the addition amount of semi-coke in the pulverized coal injection can be significantly increased to more than 60%. After pyrolysis and upgrading, the volatile matter of the semi-coke fines in the present invention can be significantly reduced from the current 8 - 12% to less than 4.5%. With the help of pyrolysis and upgrading, harmful elements such as residual sulfur and nitrogen in the semi-coke fines are further discharged with the pyrolysis gas, making the upgraded semi-coke a cleaner and purer carbon material raw material. During sintering, the fuel-type nitrogen oxides in the combustion flue gas of semi-coke account for more than 80% of all nitrogen oxides in the flue gas. Using the semi-coke fines after carbonization and upgrading can reduce the concentration of nitrogen oxides in the sintering flue gas by about 50%, thus significantly reducing the environmental protection costs of flue gas desulfurization and denitrification.

[0023] Further, the high-fixed-carbon powder material is one or more of anthracite, non-sticky bituminous coal, metallurgical coke powder, waste activated coke, and waste activated carbon. The high-fixed-carbon powder material is a raw material or solid waste in iron and steel production, and its addition can increase the grindability index of semi-coke. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic process flow diagram of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention will be described in detail below with reference to the drawings.

[0026] See Figure 1 , a method for upgrading semi-coke to prepare raw materials for pulverized coal injection and sintering according to the present invention, includes the following steps:

[0027] Step 1: Mix and knead semi-coke fines, other carbonaceous raw materials, binder, and upgrading and improving agent in a mixing device at normal temperature according to the proportion requirements to obtain a uniformly-propertied forming raw material;

[0028] Step 2: Use a high-pressure briquetting machine to press and form the forming raw material prepared in Step 1 to obtain semi-coke pellets with regular shapes;

[0029] Step 3: Transfer the semi-coke pellets prepared in Step 2 to the quality-improving treatment unit. In the carbonization and quality-improving unit, the semi-coke pellets are gradually heated from room temperature to a predetermined carbonization temperature and then stay at the carbonization temperature for a certain period of time to complete the processes of drying and dehydration as well as carbonization and quality improvement. After carbonization, the quality-improved semi-coke pellets are discharged from the bottom of the carbonization furnace.

[0030] Step 4: Crush and screen the processed quality-improved semi-coke pellets in a crushing device to obtain blowing and sintering raw materials smaller than 3 mm. Among them, the particles larger than 3 mm are returned to the crushing device for re-crushing, the fine particles of 1 - 3 mm are collected and used for sintering production, and the particles smaller than 1 mm are transported to the powder-making system for grinding and then used for blast furnace blowing.

[0031] Among them, the other carbonaceous raw materials in Step 1 are one or a mixture of two or more of high fixed-carbon powder materials such as anthracite, non-sticky bituminous coal, metallurgical coke powder, waste activated coke, and waste activated carbon. The addition amount of the other carbonaceous raw materials is 0 - 15% of the total weight of the mixed material (i.e., the forming raw material); the binder is one or several of high molecular organic compounds such as starch, coal tar, caking coal fine powder, coal pitch, and humic acid. The addition amount of the binder is 3 - 8% of the total weight of the semi-coke and the other carbonaceous raw materials; the quality-improving modifier is slaked lime or lignin powder, etc. The addition amount of the quality-improving modifier is 0 - 8% of the total weight of the semi-coke and the other carbonaceous raw materials. The specific addition situation is related to the purpose of quality improvement. If only blowing raw materials are to be produced, the quality-improving modifier can be not added.

[0032] In Step 2, the forming line pressure of the high-pressure briquetting machine should be able to reach 5 - 10 t / cm. The shape of the prepared semi-coke pellets can be regular shapes such as pillow-shaped, ellipsoidal, and oval-shaped. Preferably, the three-dimensional dimensions of the pellets are all between 15 - 25 mm.

[0033] The carbonization and quality-improving unit in Step 3 can be a carbonization furnace including a drying and dehydration section, a carbonization section, and a cooling section, or a double-furnace setting of a drying furnace + a carbonization furnace (including a cooling section), or a three-part setting of drying, carbonization, and cooling.

[0034] The carbonization and quality-improving unit in Step 3 is preferably an externally heated vertical furnace integrating drying, carbonization, and cooling. The carrier gas for carbonization is heated by a regenerative furnace. The carrier gas is preferably a reducing gas containing carbon monoxide, hydrogen, etc. or an inert gas containing nitrogen, etc. Under necessary conditions, an internally heated vertical furnace can also be used for carbonization and quality-improving operations. The hot carrier gas of the internally heated carbonization furnace is mainly combustion flue gas containing components such as nitrogen, carbon dioxide, and water vapor. Compared with the carbonization process of the internally heated carbonization furnace, the externally heated vertical furnace can avoid the gasification effect of carbon dioxide and water vapor on the pellets at high temperatures, thereby preventing the strength of the semi-coke pellets from decreasing and being crushed.

[0035] The predetermined carbonization temperature and residence time described in Step 3 can be selected according to the volatile matter requirements of the upgraded semi-coke pellets. The preferred predetermined carbonization temperature is 700 - 1000 °C, and the residence time is 2 - 6 h. When the volatile matter requirement of the upgraded semi-coke pellets is lower than 2%, long-term carbonization under the condition of 1000 °C is preferred.

[0036] The pyrolysis gas generated by the carbonization of the semi-coke pellets in the shaft furnace described in Step 3 is purified and the tar therein is recovered. The obtained tar can be sold as a by-product, and part of the pyrolysis gas from which the tar has been removed is recycled as the gaseous fuel for heating the semi-coke pellets in the carbonization furnace, and the remaining part is sent out for utilization.

[0037] The crushing equipment described in Step 4 is fine crushing equipment such as double-roll crushers, toothed-roll crushers, and cone crushers, to increase the yield of particulate products below 3 mm after single crushing.

[0038] Example 1

[0039] Step 1: Weigh and proportion the semi-coke powder, anthracite coal powder, fat coal powder, and hydrated lime powder according to the mass ratio of 80:10:8:2, and then knead them evenly at room temperature in a kneader to ensure that the fat coal powder and hydrated lime powder are evenly distributed in the semi-coke powder, obtaining a kneaded material.

[0040] Step 2: Add the kneaded material obtained in Step 1 to the hopper of a double-roll briquetting machine and press it into pillow-shaped semi-coke pellets of 22×18×15 mm under a linear pressure of 6 t / cm.

[0041] Step 3: Transfer the semi-coke pellet product obtained in Step 2 to the top hopper of the carbonization furnace and evenly add it into the carbonization furnace through the hopper valve. The selected carbonization furnace is an externally heated carbonization furnace with drying and cooling sections. The carrier gas is carbide gas mainly composed of carbon monoxide. In the carbonization furnace, the semi-coke pellets are gradually heated from room temperature to 900 °C from top to bottom and kept at a constant temperature for about 3 h, and then enter the cooling section of the carbonization furnace and are cooled to 150 °C. The cooled pellets are discharged from the bottom of the carbonization furnace and conveyed to the hopper by a high-temperature conveyor. The discharging speed of the carbonization furnace is controlled by the opening frequency and opening duration of the bottom slide valve. Take samples at the bottom discharge port of the furnace to detect the proximate analysis data of the pellets, and adjust the discharging rate of the pellets at the bottom of the furnace according to the volatile matter data of the samples. It is detected and determined that the average volatile matter of the semi-coke pellets is 3.2%, the fixed carbon content exceeds 88%, and the grindability index is 55%. It is a clean and high-quality carbonaceous material, and its performance exceeds that of the coke powder and semi-coke powder currently used for sintering and injection.

[0042] Step 4: The pellets are further cooled in the silo. After cooling, the pellets enter the crushing and screening section. A cone crusher is used to crush the upgraded semi-coke pellets. The crushed upgraded semi-coke powder is screened. The vibrating screen uses two types of screen meshes, 1 mm and 3 mm. Among them, the oversize particles of 3 mm are returned to the crusher inlet by the belt for re-crushing, the undersize particles of 1 mm are transported to the powder-making section of the injection workshop, and the fine particles of 1-3 mm are collected and transported to the fuel bin of the sintering machine. In the powder-making section, the undersize particles of 1 mm are ground by a medium-speed grinder to a fineness of 70% passing through 75 μm and used as blast furnace injection raw materials.

[0043] Example 2

[0044] Step 1: Weigh and proportion the semi-coke fines, corn starch, coal tar pitch, and lignin powder according to the mass ratio of 88:2:4:6, and then knead them evenly at room temperature in a kneader to ensure that the binder and modifier are evenly distributed in the semi-coke fines, obtaining the kneaded material.

[0045] Step 2: Add the kneaded material obtained in Step 1 to the silo of the pair-roll briquetting machine and press it into oval semi-coke pellets of 20×16×12 mm under a linear pressure of 10 t / cm.

[0046] Step 3: Transfer the semi-coke pellet product obtained in Step 2 to the top silo of the internal-heating carbonization furnace and evenly add it into the carbonization furnace through the silo valve. The carrier gas is a pyrolysis gas mainly composed of hydrogen and carbon monoxide. The semi-coke pellets in the carbonization furnace are gradually heated from room temperature to 700 °C from top to bottom and kept at a constant temperature in the high-temperature section for about 2 h, and then enter the cooling section of the carbonization furnace and are cooled to 150 °C. The cooled pellets are discharged from the bottom of the carbonization furnace and transported to the silo by a high-temperature conveyor. The discharge speed is controlled by the opening frequency and opening duration of the bottom slide valve. Samples are taken at the bottom discharge port of the furnace to detect the industrial analysis data of the pellets, and the discharge amount of the pellets at the bottom of the furnace is adjusted according to the volatile matter data of the samples. The test data of the semi-coke pellets show that the grindability index of the samples reaches 60%, the average volatile matter is 4.5%, and the fixed carbon content exceeds 86%, greatly improving the powder-making performance of the upgraded semi-coke.

[0047] Step 4: The pellets are further cooled in the silo. After cooling, the pellets are transferred to the injection workshop, mixed with other powder-making raw materials in proportion, and first crushed by a multi-stage toothed roll crusher for the upgraded semi-coke pellets. The obtained powder then enters the medium-speed grinder and is all used for powder making.

[0048] Example 3

[0049] Step 1: Weigh and proportion the semi-coke powder, metallurgical coke powder, corn starch, and humic acid according to the mass ratio of 78:15:2:5. Then, knead them at room temperature in a kneader to ensure that the two binders are evenly distributed in the semi-coke powder and coke powder. The mixed material enters a roller mill for further compaction to facilitate subsequent forming and ball pressing, obtaining a kneaded material.

[0050] Step 2: Add the mixed material obtained in Step 1 to the hopper of a pair-roll briquetting machine and press it into conical semi-coke pellets of 25×25×18 mm under a linear pressure of 5 t / cm.

[0051] Step 3: Transfer the semi-coke pellet product obtained in Step 2 to a low-temperature mesh belt drying furnace. Use the flue gas from the downstream carbonization furnace to dry the moisture of the semi-coke pellets to less than 2% at 200 - 400 °C. The dried hot pellets are conveyed by a scraper conveyor to the bell-type charging hopper of an externally heated carbonization furnace and evenly added into the carbonization furnace through the control of the hopper valve. The carrier gas is an inert gas mainly composed of nitrogen. The semi-coke pellets in the carbonization furnace are gradually heated from room temperature to 1000 °C from top to bottom, and the high-temperature carbonization time is controlled at about 5 h. Then, they enter the cooling section of the carbonization furnace and are cooled to 150 °C. The cooled pellets are discharged from the bottom of the carbonization furnace and conveyed by a high-temperature conveyor to a storage bin. The discharging speed is controlled by the opening frequency and duration of the bottom slide valve. Sample and detect the industrial analysis data of the pellets at the bottom discharge port of the furnace, and adjust the discharging rate of the pellets at the bottom of the furnace according to the volatile matter data of the sample. It is detected and determined that the average volatile matter of the semi-coke pellets is 2.1%, the fixed carbon content exceeds 92%, and the grindability index is 49%. Using this upgraded semi-coke as a sintering fuel can significantly reduce the concentrations of sulfides and nitrogen oxides in the flue gas during sintering, and its performance exceeds that of the coke powder and anthracite coal currently used in sintering.

[0052] Step 4: The pellets are further cooled in the bin. The cooled pellets enter the crushing and screening section. Use a pair-roll crusher to crush the upgraded semi-coke pellets, and adjust the roll spacing of the pair-roll crusher during crushing. Screen the crushed upgraded semi-coke powder. The vibrating screen uses two types of screen meshes, 1 mm and 3 mm. Among them, the particles on the screen with a size of 3 mm are returned to the inlet of the crusher by a belt for re-crushing. The fine particles with a size of 1 - 3 mm are collected and directly enter the fuel bin of the sintering machine. The material under the 1-mm screen is transported to the injection workshop for powder making treatment.

[0053] Example 4

[0054] Step 1: Weigh and proportion the semi-coke powder, high fixed-carbon powder, binder, and quality-improving modifier, and then knead them evenly at room temperature in a kneader to ensure that the binder and modifier are evenly distributed in the semi-coke powder, obtaining a kneaded material. Among them, the high fixed-carbon powder is a mixture of anthracite and non-sticky bituminous coal, and the dosage of the high fixed-carbon powder is 15% of the weight of the kneaded material. The binder is a mixture of starch and coal tar, and the dosage of the binder is 3% of the total weight of the semi-coke powder and the high fixed-carbon powder. The quality-improving modifier is slaked lime, and the dosage of the quality-improving modifier is 8% of the total weight of the semi-coke powder and the high fixed-carbon powder.

[0055] Step 2: Add the kneaded material obtained in Step 1 to the hopper of a pair-roll briquetting machine and press it into a pillow-shaped semi-coke pellet of 22×18×15 mm under a linear pressure of 8 t / cm.

[0056] Step 3: Transfer the semi-coke pellet product obtained in Step 2 to the top hopper of a carbonization furnace and evenly add it into the carbonization furnace through the hopper valve. The selected carbonization furnace is an externally heated carbonization furnace with drying and cooling sections. The carrier gas is carbide gas mainly composed of carbon monoxide. In the carbonization furnace, the semi-coke pellets are gradually heated from room temperature to 700 °C from top to bottom and kept at a constant temperature for about 6 h, and then enter the cooling section of the carbonization furnace and are cooled to 150 °C. The cooled pellets are discharged from the bottom of the carbonization furnace and conveyed to the hopper by a high-temperature conveyor. The discharging speed of the carbonization furnace is controlled by the opening frequency and opening duration of the bottom slide valve. Take samples at the bottom discharge port of the furnace to detect the industrial analysis data of the pellets, and adjust the discharging rate of the pellets at the bottom of the furnace according to the volatile matter data of the samples.

[0057] Step 4: The pellets are further cooled in the hopper. After cooling, the pellets enter the crushing and screening section, and a cone crusher is used to crush the quality-improved semi-coke pellets. Screen the crushed quality-improved semi-coke powder. The screens of the vibrating screen are selected as 1 mm and 3 mm. Among them, the particles on the screen with a size of 3 mm are returned to the inlet of the crusher by the belt for re-crushing, and the materials passing through the 1-mm screen are transported to the powder-making section of the injection workshop. The fine particles with a size of 1-3 mm are collected and transported to the fuel bin of the sintering machine. In the powder-making section, the materials passing through the 1-mm screen are ground by a medium-speed grinder to a fineness with 70% of the particles being 75 μm and then used as blast furnace injection raw materials.

[0058] Example 5

[0059] Step 1: Weigh and proportion the semi-coke powder and the binder, and then knead them evenly at room temperature in a kneader to ensure that the binder and modifier are evenly distributed in the semi-coke powder, obtaining a kneaded material. Among them, the binder is a mixture of starch and coal tar, and the dosage of the binder is 8% of the total weight of the semi-coke powder and the high fixed-carbon powder.

[0060] Step 2: Add the mixture obtained in Step 1 to the hopper of a pair-roll briquetting machine and press it into a conical semi-coke pellet of 25×25×18 mm under a linear pressure of 5 t / cm.

[0061] Step 3: Transfer the semi-coke pellet products obtained in Step 2 to a low-temperature mesh belt dryer. Using the flue gas from the downstream carbonization furnace, dry the moisture of the semi-coke pellets to less than 2% at 200 - 400 °C. The dried hot pellets are conveyed by a scraper conveyor to the bell-type charging hopper of the externally heated carbonization furnace and evenly added into the carbonization furnace through the control of the hopper valve. The carrier gas is an inert gas mainly composed of nitrogen. The semi-coke pellets in the carbonization furnace are gradually heated from room temperature to 800 °C from top to bottom, and the high-temperature carbonization time is controlled at about 5 h. Subsequently, they enter the cooling section of the carbonization furnace and are cooled to 150 °C. The cooled pellets are discharged from the bottom of the carbonization furnace and conveyed by a high-temperature conveyor to the storage bin. The discharging speed is controlled by the opening frequency and duration of the bottom slide valve. Sample and detect the industrial analysis data of the pellets at the bottom discharge port of the furnace, and adjust the discharging rate of the pellets at the bottom of the furnace according to the volatile matter data of the sample.

[0062] Step 4: The pellets are further cooled in the bin. The cooled pellets enter the crushing and screening section. Use a pair of roll crushers to crush the upgraded semi-coke pellets, and adjust the roll spacing of the pair of roll crushers during crushing. Screen the crushed upgraded semi-coke powder. The vibrating screen meshes are selected as 1 mm and 3 mm. Among them, the particles on the screen with a size of 3 mm are returned to the crusher inlet by the belt for re-crushing, the fine particles with a size of 1 - 3 mm are collected and directly enter the fuel bin of the sintering machine, and the materials passing through the 1-mm screen are transferred to the injection workshop for powder making treatment.

[0063] Example 6

[0064] Step 1: Weigh and proportion semi-coke powder, high fixed-carbon powder, binder, and upgrading modifier, and then knead them evenly at room temperature in a kneader to ensure that the binder and modifier are evenly distributed in the semi-coke powder, obtaining a kneaded material; among them, the high fixed-carbon powder is a mixture of metallurgical coke powder, waste activated coke, and waste activated carbon. The dosage of the high fixed-carbon powder is 7% of the weight of the kneaded material. The binder is a mixture of caking coal pulverized coal and coal tar pitch. The dosage of the binder is 5% of the total weight of the semi-coke powder and the high fixed-carbon powder. The upgrading modifier is lignin powder; the dosage of the upgrading modifier is 5% of the total weight of the semi-coke powder and the high fixed-carbon powder.

[0065] Step 2: Add the kneaded material obtained in Step 1 to the hopper of a pair of roll pelletizers and press it into oval semi-coke pellets with a size of 20×16×12 mm under a linear pressure of 10 t / cm.

[0066] Step 3: Transfer the semi-coke pellet product obtained in Step 2 to the top bunker of the internally heated carbonization furnace, and uniformly add it into the carbonization furnace through the bunker valve. The carrier gas is pyrolysis gas mainly composed of hydrogen. The semi-coke pellets are gradually heated from room temperature to 700 °C from top to bottom in the carbonization furnace, and are kept at a constant temperature for about 2 h in the high-temperature section, and then enter the cooling section of the carbonization furnace and are cooled to 150 °C. The cooled pellets are discharged from the bottom of the carbonization furnace and conveyed to the bunker by a high-temperature conveyor. The discharging speed is controlled by the opening frequency and opening duration of the bottom slide valve.

[0067] Step 4: The pellets are further cooled in the bunker. After cooling, the pellets are transferred to the injection workshop. After being proportionally added and mixed with other pulverized raw materials, the upgraded semi-coke pellets are first crushed by a multi-stage toothed roll crusher, and the obtained powder then enters a medium-speed mill and is all used for pulverization.

[0068] The present invention provides a new treatment process of cold pressing and shaft furnace carbonization upgrading, which upgrades and modifies semi-coke powder to customize and produce upgraded raw materials for high-performance injection and sintering. The volatile content of semi-coke is further reduced, which can effectively reduce fuel-type nitrogen oxides in sintering flue gas and save the cost of subsequent tail gas treatment.

Claims

1. A method for upgrading semi-coke to prepare raw materials for injection and sintering, characterized in that, The method includes the following steps: Mix and knead semi-coke powder, high fixed-carbon powder, binder and quality-improving agent to obtain shaped raw materials; wherein, the quality-improving agent is quicklime, slaked lime or lignin powder; Press the shaped raw materials to form semi-coke pellets with regular shapes; wherein, the linear pressure for pressing the shaped raw materials is 5-10 t / cm; Carbonize the semi-coke pellets to obtain quality-improved semi-coke pellets; Crush and screen the quality-improved semi-coke pellets to obtain raw materials for injection and sintering; The mass ratio of the quality-improving agent to the total weight of semi-coke and high fixed-carbon powder is 2:98-8:100; The specific process of carbonizing the semi-coke pellets includes drying and dehydration, carbonization and cooling or includes drying and carbonization; The carbonization is carried out in one or more of the gases including carbon monoxide, hydrogen and nitrogen; the carbonization temperature is 700-1000 °C, and the time is 2-6 h.

2. The method for preparing raw materials for injection and sintering by upgrading semi-coke according to claim 1, wherein The high fixed-carbon powder is one or more of anthracite, non-sticky bituminous coal, metallurgical coke powder, waste activated coke and waste activated carbon.

3. A method for upgrading semi-coke to prepare raw materials for injection and sintering according to claim 1, characterized in that, The addition amount of the high fixed-carbon powder is 0-15% of the total weight of the shaped raw materials.

4. A method for upgrading semi-coke to prepare raw materials for injection and sintering according to claim 1, characterized in that, The binder is one or more of starch, coal tar, caking coal fine powder, coal tar pitch and humic acid.

5. A method for upgrading semi-coke to prepare raw materials for injection and sintering according to claim 1, characterized in that, The addition amount of the binder is 3-8% of the total weight of semi-coke and high fixed-carbon powder.

6. A method for upgrading semi-coke to prepare raw materials for injection and sintering according to claim 1, characterized in that, The shape of the semi-coke pellets is pillow-shaped, ellipsoidal or oval.

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