CN113817521A

CN113817521A - Preparation method of biomass charcoal composite fuel for blast furnace injection

Info

Publication number: CN113817521A
Application number: CN202111038078.9A
Authority: CN
Inventors: 王臣; 王广伟; 毛晓明; 熊林; 王川; 宁晓钧
Original assignee: Baoshan Iron and Steel Co Ltd; University of Science and Technology Beijing USTB
Current assignee: Baoshan Iron and Steel Co Ltd; University of Science and Technology Beijing USTB
Priority date: 2021-09-06
Filing date: 2021-09-06
Publication date: 2021-12-21

Abstract

The invention provides a method for preparing a biomass-charcoal composite fuel for blast furnace injection. The crushed biomass raw material and low-metamorphic coal are subjected to mixed hydrothermal carbonization treatment, then mixed with preheated high-metamorphic coal and kept warm, and finally Autoclave. The invention utilizes the minerals in the low-rank coal to improve the yield of biomass hydrothermal carbonization, meanwhile, the ash, volatile matter and moisture in the low-rank coal can also be partially removed, and the bonding performance is improved. Mixing with preheated highly metamorphic coal can increase the ignition point of the mixture, reduce the explosiveness of the mixture, and further enhance the ash melting point of the composite fuel by utilizing the high ash melting point of the highly metamorphic coal. The biomass carbon composite fuel of the invention can completely replace fossil fuels for blast furnace injection, thereby reducing the emission of carbon dioxide and pollutants in the ironmaking production process, and the hot-pressed fuel has the characteristics of high bulk density and high compressive strength. Suitable for long-distance transportation and long-term storage.

Description

Preparation method of biomass charcoal composite fuel for blast furnace injection

Technical Field

The invention relates to the technical field of blast furnace ironmaking, in particular to a preparation method of a biomass charcoal composite fuel for blast furnace injection.

Background

With the continuous development of economy in China, the living standard of people is continuously improved, and the demand of social infrastructure on steel materials is continuously increased. In 2019, the yield of crude steel in China reaches 9.96 hundred million tons, the yield of pig iron also reaches 8.09 hundred million tons, and the double-refreshing history is new and high. Because of the energy structure of rich coal, less oil and gas shortage, the non-blast furnace ironmaking technologies such as gas-based direct reduction and the like cannot be popularized and applied in China, and the blast furnace ironmaking production process flow is still the main point at present. Nearly 600kg of coal is consumed for producing 1 ton of molten iron in blast furnace ironmaking, and the coal consumption of steel production reaches 4 hundred million tons in China every year, which accounts for nearly 10 percent of the total coal consumption in China. Because coal belongs to non-renewable resources, the mining, processing and using processes of the coal all cause pollution to the environment, and the release of carbon dioxide by combustion is even more a climate problem such as global warming. The search for environment-friendly fuels becomes one of the important tasks of reducing the coal consumption in iron-making production, developing green steel technology and realizing low-carbon metallurgy.

The implementation of the technology of blowing the coal powder into the blast furnace greatly reduces the coke consumption in the blast furnace production, can effectively reduce the pollutant discharge in the steel production while reducing the iron-making production cost, and becomes one of the main technologies for the green development of the steel. The early blast furnace production injection pulverized coal completely adopts anthracite, and the characteristic of high fixed carbon content in the anthracite is utilized to replace blast furnace metallurgical coke. Later, as the supply of anthracite and the reserve of raw coal are continuously reduced and the price is continuously increased, the mixing and spraying of the bituminous coal which is cheaper and has richer reserves and the anthracite become the main measure for further reducing the cost of molten iron of iron and steel enterprises. Recently, the resource of blast furnace injection fuel is expanded to be the key work concerned by a plurality of iron and steel enterprises, and lean coal, lignite, semi coke and upgraded coal are one of the resources selected by the blast furnace coal powder injection technology. Meanwhile, as a large country for agricultural production, China has abundant biomass resources, the amount of agricultural and forestry wastes generated each year reaches 20.29 hundred million tons, the amount of the wastes which can be recycled reaches 13.24 hundred million tons, and the amount of the wastes is reduced to 3.82 hundred million tons by standard coal, and the use of biomass as blast furnace injection fuel is also concerned by a plurality of ironmaking producers. Compared with fossil fuels, the biomass resources have the characteristics of regeneration and carbon neutrality, carbon dioxide released in the combustion process can be absorbed again through light and action in the production process, and the biomass resources injected in blast furnace ironmaking can effectively reduce the emission of ironmaking production pollutants and carbon dioxide.

Compared with fossil fuels such as anthracite, bituminous coal, lean coal, lignite, semi-coke, upgraded coal and the like, biomass with the potential of replacing fossil fuels has the characteristics of wide source, reproducibility and good combustion performance, but the following problems generally exist: 1) the defects of high moisture content, low fixed carbon and calorific value, low energy density, looseness and porosity seriously affect the transportation, storage and use of the carbon fiber; 2) the straw biomass has the problems of high ash content and alkali metal content, the direct injection of the blast furnace is continuously used, so that gun blockage and tuyere small sleeve slag bonding are easily caused, the high-temperature metallurgical performance of coke, sinter and pellet in the blast furnace can be strongly damaged, and the production economic and technical indexes of the blast furnace are seriously influenced; 3) the main components of biomass comprise cellulose, hemicellulose and lignin, so that the biomass generally has strong toughness, and powder making equipment such as a medium-speed mill, a ball mill and the like is difficult to crush the biomass into the particle size required by fuel injected into a blast furnace.

Therefore, if biomass resources are applied to blast furnace ironmaking production efficiently, upgrading treatment of the biomass is needed. The biomass pyrolysis carbonization can effectively remove moisture and volatile components in the biomass raw material, and improve the content and calorific value of fixed carbon. However, due to the enrichment of ash caused by the pyrolysis and carbonization processes, the ash content in the prepared biomass pyrolytic carbon is greatly improved, and the alkali metal content far exceeds the requirement of pulverized coal injection of a blast furnace. Meanwhile, the ash melting point is low due to the high content of alkali metal and alkaline earth metal in the biomass pyrolytic carbon, and the normal production of the blast furnace is influenced due to the fact that a gun is easily blocked by the blast furnace and a tuyere is easily subjected to small sleeve slag bonding when the blast furnace is blown; the increase in alkali load also affects the metallurgical properties of coke and ore in the blast furnace. In addition, although the energy density of the biomass charcoal is improved to a certain degree, the biomass charcoal still has small volume density, and segregation is easily caused when the biomass charcoal is mixed with pulverized coal for pulverizing and injecting, so that pulverization, conveying and injecting of a mixed sample are influenced.

In view of the above, there is a need to design an improved method for preparing a biomass charcoal composite fuel for blast furnace injection to solve the above problems.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a preparation method of biomass charcoal composite fuel for blast furnace injection, which is characterized in that biomass charcoal and low-metamorphic coal are mixed for hydrothermal carbonization treatment to prepare the biomass charcoal composite fuel, and the problem of high ash content and alkali metal content in the biomass charcoal is solved by adopting a hydrothermal carbonization technology; the characteristic of high reactivity of the biomass charcoal is utilized to promote the rapid ignition and combustion of the high-metamorphic coal, and the performance of high ash melting point of the high-metamorphic coal is utilized to overcome the defect of low ash melting point of the biomass; in addition, compact and hard waterproof massive fuel is obtained through heating and high-pressure compression molding, the performance requirements of long-distance transportation and long-term storage can be met, and the segregation problem faced when the biomass charcoal and blast furnace injection coal are mixed for milling and injection is avoided.

In order to realize the aim, the invention provides a preparation method of biomass charcoal composite fuel for blast furnace injection, which comprises the following steps:

s1, mixing the crushed biomass raw material and low metamorphic coal according to a preset mass ratio, and then carrying out hydrothermal carbonization treatment together to obtain composite hydrothermal carbon;

s2, preheating the crushed high-metamorphic coal, mixing the preheated high-metamorphic coal with the composite hydrothermal carbon obtained in the step S1 according to a preset mass ratio, preserving heat at a preset temperature, and performing hot-press forming to obtain the biomass carbon composite fuel for blast furnace injection.

As a further improvement of the invention, in step S1, the preset mass ratio of the biomass to the low metamorphic coal is (85-95): 5-15).

As a further improvement of the invention, in step S1, the temperature of the hydrothermal carbonization treatment is controlled to be 220-350 ℃, the corresponding saturated vapor pressure is 2.3-16.5 MPa, and the treatment time is controlled to be 0.5-3 h.

As a further improvement of the invention, in step S2, the high metamorphic coal is preheated to 650-700 ℃ by using a heating furnace, and the temperature of the composite hydrothermal carbon is controlled to 80-250 ℃.

As a further improvement of the invention, in step S2, after the composite hydrothermal carbon and the preheated high-metamorphic coal are mixed according to the weight ratio of (30-90) to (10-70), the temperature is controlled to be 300-450 ℃ and the temperature is kept.

As a further improvement of the invention, in step S2, the hot pressing temperature is 300-450 ℃, the pressure is 10-60 MPa, and the time is 0.1-3 min.

As a further improvement of the invention, the biomass comprises but is not limited to one or a mixture of several biomass in agricultural wastes, forestry wastes and municipal organic wastes, and the low metamorphic coal comprises but is not limited to one or a mixture of several gas coal, fat coal, coking coal, lean coal and lean coal with caking property; the high metamorphic coal includes but is not limited to anthracite, semi coke, upgraded coal, coke and carbon black.

As a further improvement of the invention, the particle sizes of the crushed biomass, the crushed low-metamorphic coal and the crushed high-metamorphic coal are all 0-3 mm.

As a further improvement of the invention, the bulk density of the biomass charcoal composite fuel for blast furnace injection is 0.9-2.5 g/cm³The compression strength is more than or equal to 0.1MPa, the diameter is 8-30 mm, the length-diameter ratio is 1-6, and the forming rate is more than or equal to 95 percent; the blast furnace injectionThe biomass charcoal composite fuel has dry base ash content not more than 10%, dry base fixed carbon not less than 65%, heat value not less than 26MJ/kg, sulfur content not more than 0.3%, alkali metal K + Na not more than 0.1%, ash melting point not less than 1200 deg.c, and Hastelloy index not less than 60%.

As a further improvement of the invention, the biomass charcoal composite fuel for blast furnace injection is crushed and mixed with pulverized coal for blast furnace injection when in use.

The invention has the beneficial effects that:

1. according to the preparation method of the biomass charcoal composite fuel for blast furnace injection, provided by the invention, the biomass and the low-rank coal raw material are subjected to mixed hydrothermal carbonization treatment, so that on one hand, partial ash content and alkali metal elements in the biomass and the low-rank coal can be removed; on the other hand, the low-rank coal is rich in mineral substances, so that the yield of biomass hydrothermal carbonization can be improved, meanwhile, ash, volatile matters and water in the low-rank coal can be partially removed, the cohesiveness is improved, the quality of a carbonized product is improved, and high-quality hydrothermal carbon with low ash and alkali metal content, high fixed carbon content and moderate water content is obtained. And then, hot-press molding is carried out on the high-ash-melting-point high-metamorphic coal, and the ash melting point of the composite fuel is further improved by utilizing the characteristic of the high ash melting point of the high-metamorphic coal. The prepared biomass charcoal composite fuel has good combustion performance and reaction performance, and the high combustion performance and reactivity of the biomass charcoal in the blast furnace injection process can promote the rapid ignition and combustion of high-metamorphic coal and improve the combustion performance of the composite fuel.

2. The biomass charcoal composite fuel has low content of alkali metal (K, Na). The hydrothermal carbonization of the biomass can effectively remove water-soluble alkali metal compounds, and solves the problem of high alkali metal content when the biomass is applied to blast furnace blowing.

3. The biomass charcoal composite fuel has a higher calorific value. Compared with biomass charcoal, the pulverized coal has the characteristics of high fixed carbon content and high calorific value, and the biomass charcoal composite fuel prepared by pressing the biomass hydrothermal charcoal, the low-metamorphic coal and the high-metamorphic coal by adopting the hot press molding technology has the characteristics of low ash content and moisture content and high fixed carbon content, and increases the calorific value of the biomass charcoal composite fuel.

4. The biomass charcoal composite fuel meets the requirements of long-distance transportation and long-time storage. The biomass and biomass charcoal composite fuel has the characteristics of low energy density, developed pore structure and easiness in water absorption, so that the biomass and charcoal composite fuel has difficulty in transportation and storage, and the compact, hard and waterproof massive biomass charcoal composite fuel obtained by heating and pressing can meet the performance requirements of long-distance transportation and long-term storage.

5. The powder preparation, pipeline transportation and injection performance of the biomass charcoal composite fuel are improved. The biomass charcoal and the bituminous coal and the anthracite injected by the blast furnace still have larger density difference, so that the problem of segregation exists in the processes of pulverizing, conveying and injecting, the biomass charcoal composite fuel formed by hot pressing is compact and hard, can be directly crushed by coal injection pulverizing equipment in an iron-making plant, the aim of uniformly mixing the biomass hydrothermal charcoal and the pulverized coal is realized in the crushing process, and the pulverizing, pipeline conveying and injecting performances of the mixed fuel are improved.

6. The biomass-carbon composite fuel can improve the comprehensive utilization efficiency of biomass resources, reduce the influence of biomass blast furnace injection on blast furnace alkali load, and is beneficial to stable and smooth blast furnace smelting.

Drawings

FIG. 1 is a schematic flow chart of a preparation method of a biomass charcoal composite fuel for blast furnace injection according to the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in detail below with reference to specific embodiments.

It should be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and/or processing steps closely related to the scheme of the present invention are shown in the specific embodiments, and other details not closely related to the present invention are omitted.

In addition, it is also to be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Referring to fig. 1, the preparation method of the biomass charcoal composite fuel for blast furnace injection provided by the invention specifically comprises the following steps:

1) removing impurities from a biomass raw material by using a coarse screen and an iron remover, crushing, and crushing low metamorphic coal and high metamorphic coal;

2) mixing the crushed biomass and the low metamorphic coal according to a mass ratio of (85-95) to (5-15) (mixture I), and then carrying out hydrothermal carbonization treatment to obtain composite hydrothermal carbon; the hydrothermal carbonization treatment is adopted, the special performance of subcritical water is utilized to carry out modification treatment on biomass and low metamorphic coal, the characteristics of low energy consumption, good pollutant discharge amount and uniform and stable performance of the prepared hydrothermal carbon are achieved, and the bonding performance of the low metamorphic coal can be improved, so that the performance requirement of hot press molding of a mixed sample can be met. The wastewater generated in the biomass and low-rank coal hydrothermal carbonization process can be recycled after deoiling and desalting treatment, so that no harmful substance is discharged in the whole treatment process, the purposes of resource utilization of the biomass, reduction of coking cost, saving of coking coal resources and reduction of carbon dioxide and pollutant discharge are achieved, and the method has good environmental and economic benefits.

3) Preheating the crushed high-metamorphic coal by using a heating furnace; mixing the composite hydrothermal carbon obtained in the step 2) with preheated high-metamorphic coal according to the mass ratio of (30-90) to (10-70) (mixture II), and preserving heat at 300-450 ℃;

4) and (3) pressing the mixture II obtained in the step (3) at the temperature of 300-450 ℃ and under the pressure of 10-60 MPa for 0.1-3 min to obtain the formed biomass charcoal composite fuel. Through the effect of the forming pressure, the gaps among different fuel particles are reduced, the interaction of active chemical bonds is promoted, the bonding is facilitated, and the forming density and the strength of the biomass charcoal composite fuel are improved. The biomass charcoal composite fuel formed by hot pressing is compact and hard, can be directly crushed by coal injection and pulverized coal preparation equipment in an iron works, the aim of uniformly mixing biomass hydrothermal charcoal and pulverized coal is fulfilled in the crushing process, and the powder preparation, pipeline transportation and injection performance of the mixed fuel are improved.

By adopting the technical scheme, after being crushed, biomass and low-rank coal raw materials are mixed according to a certain proportion and then are subjected to hydrothermal carbonization treatment, and partial ash and alkali metal elements in the biomass and low-rank coal are removed; meanwhile, the low-rank coal is rich in minerals (the main component of the minerals comprises Al)₂O₃、CaO、Fe₂O₃MgO), the existence of mineral substance can promote the yield of living beings hydrothermal carbonization, simultaneously, the hydrothermal carbonization process jointly of living beings and low order coal, ash content, volatile matter and moisture in the low order coal also can be by partial desorption, cohesiveness can be improved, the quality of carbomorphism product has been promoted (show that fixed carbon content increases, the ash content reduces, the calorific value promotes, hot briquetting ability can obtain promoting), obtain ash content and alkali metal content low, fixed carbon content is high, moisture content moderate high quality hydrothermal charcoal.

The high-metamorphic coal is subjected to preheating treatment, the preheated high-metamorphic coal is mixed with the prepared hydrothermal carbon, the mixture is guaranteed to be 300-450 ℃, the mixture has good bonding performance, and the forming rate and the strength of a hot-press forming product are guaranteed. The ash content of biomass and bituminous coal contains a large amount of soluble alkali metal and alkaline earth metal compounds, so that the ash melting point of the biomass and bituminous coal is lower, the ash melting point of hydrothermal carbon is improved by removing the alkali metal and the alkaline earth metal through hydrothermal carbonization, the biomass and bituminous coal is subjected to hot press forming with high-ash-melting-point high-metamorphic coal, and the ash melting point of the composite fuel is further improved by utilizing the characteristic of the high-ash-melting-point of the high-metamorphic coal.

In the step 1), the particle size of the crushed biomass, low-metamorphic coal and high-metamorphic coal is 0-3 mm. The hydrothermal reaction can be accelerated by controlling the granularity, the physical and chemical performance index and uniformity of the prepared hydrothermal carbon are improved, meanwhile, the contact area among different particles in the hot pressing process can be increased, and the strength of a force chain and the hydrogen bond force are increased.

In the step 2), the hydrothermal carbonization temperature of the mixture I is controlled to be 220-350 ℃, the corresponding saturated vapor pressure is 2.3-16.5 MPa, and the treatment time is controlled to be 0.5-3 h. Through optimizing the parameters of the hydrothermal carbonization process, the biomass and the low-rank coal are hydrothermally decomposed into the hydrothermal carbon with low ash content and alkali metal content, high fixed carbon content and certain cohesiveness, so that the performance of the hydrothermal carbon can meet the quality requirement of hot pressing.

In the step 3), the temperature of the composite hydrothermal carbon is controlled to be 80-250 ℃, and the highly-metamorphic coal is preheated to 650-700 ℃ by using a heating furnace. The operation is carried out in such a way that the mixture II can reach 300-450 ℃, and the hot-press forming at the temperature has the best effect. Because the hydrothermal carbon has strong explosiveness, in order to improve the safety, the temperature of the composite hydrothermal carbon is maintained below 250 ℃ by using the residual temperature after hydrothermal carbonization, and the high-metamorphic coal has no explosiveness and can be safely heated to a higher temperature, so that the temperature of the mixture II reaches 450 ℃, but the explosiveness of the mixture II is reduced due to the blending of the high-metamorphic coal, and the production safety can be ensured.

The bulk density of the formed biomass charcoal composite fuel in the step 4) is 0.9-2.3 g/cm³The compression strength is more than or equal to 0.1MPa, the diameter is 8-30 mm, the length-diameter ratio is 1-6, and the forming rate is more than or equal to 95%. The formed biomass charcoal composite fuel has dry basis ash content of less than or equal to 10%, dry basis fixed carbon of more than or equal to 65%, heat value of more than or equal to 26MJ/kg, sulfur content of less than or equal to 0.3%, alkali metal (K + Na) of less than or equal to 0.1%, ash melting point of more than or equal to 1200 ℃ and Hashimoto grindability index of more than or equal to 60%.

The biomass comprises one or a mixture of several biomass including agricultural waste, forestry waste and municipal organic waste. The low metamorphic coal comprises one or a mixture of more of gas coal, fat coal, coking coal, lean coal and lean coal with caking property. The high-metamorphic coal comprises one or a mixture of more of anthracite, semi coke, upgraded coal, coke and carbon black.

The biomass charcoal composite fuel prepared by the method can completely replace fossil fuel for blast furnace injection.

Example 1

A biomass charcoal composite fuel for blast furnace injection is prepared by taking soybean straws from agricultural production as a biomass raw material through the following steps:

(1) removing impurities such as small stones and iron wires from the collected soybean stalks by using a vibrating screen and a strong magnetic iron remover, and crushing the soybean stalks into straw scraps with the granularity less than 3mm by using a shearing crusher.

The low-rank coal in this example was lean (16.7% volatile matter, 9.5% ash, and 18% G), and large pieces of lean coal were crushed into particles having a particle size of less than 3mm by a crusher.

Respectively weighing the crushed soybean straws and the lean coal, forming a mixture I according to the mass ratio of 85:15, uniformly mixing the mixture I and the ironmaking wastewater according to a proper ratio, and adding the mixture I and the ironmaking wastewater into a high-pressure reaction kettle for hydrothermal carbonization reaction. The hydrothermal carbonization temperature is 220 ℃, the pressure is 2.3MPa of saturated vapor pressure, and the reaction time is 3 h. And transferring the reactant to a solid-liquid separation device after the hydrothermal carbonization reaction is finished, separating a solid product from a liquid product to obtain the composite hydrothermal carbon, and recycling the residual wastewater after the liquid product is subjected to deoiling, desalting and purifying treatment.

After the composite hydrothermal carbon is dried, component detection is carried out, the volatile content of a drying base is 36.8%, the ash content of the drying base is 4.3%, and the content of alkali metal of the drying base is 0.06%. The prepared composite hydrothermal carbon is heated and insulated by high-temperature steam generated by a flash tank, and the insulation temperature is 80 ℃.

(2) The selected anthracite has 8.3% of volatile matter and 9.1% of ash content. Anthracite is preheated to 700 ℃ by using a heating furnace, the heated composite hydrothermal carbon and the anthracite are uniformly mixed according to the mass ratio of 40:60 to obtain a mixture II, and the temperature of the mixture II is controlled to be 450 ℃. And placing the mixture II in a hot-pressing mold, and pressing and molding on a press machine under the pressure of 60MPa for 0.3min to obtain the biomass charcoal composite fuel.

The result of detecting the quality of the biomass charcoal composite fuel is as follows: the bulk density is 2.33g/cm³The columnar fuel with the diameter of 15mm and the length-diameter ratio of 2-3 has the compression strength of 0.23MPa and the forming rate of 96 percent. The water content of the formed biomass charcoal composite fuel is 1.3%, the volatile content of a dry base is 18.6%, the ash content of the dry base is 7.2%, the heating value of the dry base is 28.5MJ/kg, the sulfur content is 0.28%, and alkali metal is addedThe (K + Na) content is 0.09%, the ash melting point reaches 1332 ℃, and the Hardgrove grindability index is 68.3%.

The biomass charcoal composite fuel prepared by the implementation method has the advantages that the volume density is greatly increased, the powdery particles are reduced, and long-distance transportation and long-time storage are facilitated; the volatile content meets the safety requirements of a blast furnace powder making and injection system, and the production safety can be ensured; the higher heating value can provide sufficient heat for blast furnace smelting, and is beneficial to reducing the fuel ratio; the lower sulfur content and alkali metal content are beneficial to improving the economic and technical indexes of blast furnace smelting; the high Haw's grindability coefficient can satisfy the requirement of the intermediate speed mill powder process of enterprise, is favorable to improving the machine hour output and reducing the powder process composition. The performance of the biomass charcoal composite fuel prepared on the whole can meet the technical requirement of solid fuel injection of a blast furnace, and the biomass charcoal composite fuel can completely replace pulverized coal for blast furnace injection and reduce the consumption of fossil fuel in iron-making production.

Examples 2 to 5

Examples 2 to 5 provide biomass charcoal composite fuel for biomass blast furnace injection, which is different from example 1 in that the mass ratio of soybean straw to lean coal, the hydrothermal carbonization temperature and the hydrothermal carbonization time are shown in table 1. Other preparation methods are substantially the same as those of example 1, and are not repeated herein. Table 2 shows the properties of the biomass charcoal composite fuel prepared in examples 2 to 5.

TABLE 1 preparation conditions of examples 2 to 5 and technical indices of the prepared hydrothermal charcoal

Table 2 Properties of Biomass charcoal composite fuels prepared in examples 2-5

Examples	Example 2	Example 3	Example 4	Example 5
					Bulk Density (g/cm)³)	2.39	2.43	2.48	2.49
Molding ratio (%)	95	96	94	94
					Compressive strength (MPa)	0.23	0.24	0.22	0.23
Moisture (%)	1.3	1.2	1.2	1.2
					Dry basis volatiles (%)	17.3	16.9	16.2	15.3
Dry basis ash (%)	7.1	6.9	6.7	6.6
					Heating value of drying base (MJ/kg)	28.7	29.1	29.3	29.6
Sulfur content (%)	0.27	0.27	0.26	0.25
					Alkali Metal (K + Na) (%)	0.09	0.08	0.08	0.09
Ash melting Point (. degree. C.)	1350	1335	1335	1317
					Ha's grindability index (%)	69.2	69.7	70.3	70.5

As can be seen from Table 1, the volatile matter of the drying base of the hydrothermal carbon prepared in examples 2 to 5 is between 38.6% and 43.5%, and the ash content is between 3.7% and 4.2%. Compared with the hydrothermal carbonization time, the hydrothermal carbonization temperature has more obvious influence on the components of the prepared hydrothermal carbon, and the volatile components and the ash content of the composite hydrothermal carbon drying base are gradually reduced along with the increase of the hydrothermal carbonization temperature. The main reasons are that the higher hydrothermal carbonization temperature can promote the degradation of main components such as cellulose, hemicellulose and lignin in the soybean straws and accelerate the removal of volatile matters, and meanwhile, the ash content in the soybean straws and lean coal contains water-soluble mineral substances, so that the increase of the hydrothermal carbonization temperature accelerates the migration of the soluble mineral substances to a liquid phase and reduces the ash content in the prepared hydrothermal carbon.

And carrying out hot pressing on the prepared hydrothermal carbon and preheated anthracite to prepare the biomass carbon composite fuel. The volume density of the biomass charcoal composite fuel prepared and obtained is 2.39g/cm³～2.49g/cm³The high-strength high-heat-resistance high-temperature-resistant coal has high forming rate (94% -96%), compressive strength of 0.23-2.24 MPa, moisture content of 1.2% -1.3%, volatile components of a drying base of 15.3% -17.3%, ash content of the drying base of 6.6% -7-29.6 MJ, a heating value of the drying base of 28.7-1350.6 MJ, the sulfur content of the sample is kept between 0.25% -0.27%, the alkali metal content of the alkali metal meets the requirement of the ultra-low-alkalinity-resistant high-temperature-resistant high. As can be seen from Table 2, the components for preparing the biomass charcoal composite fuel and the blast furnace injection process performance under different conditions are slightly different, but the biomass charcoal composite fuel can meet the requirement of blast furnace injection, can be used as a substitute fuel of blast furnace injection pulverized coal, and can reduce the consumption of fossil fuels in iron-making production.

Examples 6 to 10

Embodiments 6 to 10 provide biomass charcoal composite fuel for biomass blast furnace injection, which is different from embodiment 3 in that the heat preservation temperature of hydrothermal charcoal, the preheating temperature of anthracite, and the ratio of hydrothermal charcoal anthracite are shown in table 3. The other preparation methods are substantially the same as those of example 3, and are not repeated herein. Table 4 shows the properties of the biomass charcoal composite fuel prepared in examples 6 to 10.

TABLE 3 preparation parameters for examples 6 to 10

Examples	Composite hydrothermal charcoal insulation temperature (DEG C)	Anthracite preheating temperature (DEG C)	Compounding water heating charcoal: anthracite coal
				Example 6	140	650	30:70
Example 7	140	700	40:60
				Example 8	140	700	50:50
Example 9	200	650	50:50
				Example 10	250	650	50:50

Table 4 Performance of examples 6-10 for preparing biomass charcoal composite fuel

As can be seen from Table 4, the biomass charcoal composite fuel prepared in examples 6 to 10 has a bulk density of 2.36g/cm³～2.63g/cm³The samples prepared in different embodiments have larger difference, which is mainly caused by the mixture ratio of the composite hydrothermal carbon and the anthracite. The bulk density and the true density of the anthracite are both larger, and the volume density of the biomass carbon composite fuel can be increased by improving the proportion of the anthracite. Meanwhile, it can be seen that the forming rate is gradually reduced along with the increase of the proportion of the anthracite, and the forming rate is increased when the composite hydrothermal carbon: when the anthracite data is 30:70, the forming rate is reduced to 85%, and in order to ensure that the biomass charcoal composite fuel has higher forming rate, the proportion of the hydrothermal charcoal needs to be controlled to be more than 30%. The compressive strength is more than 0.19 MPa.

The biomass charcoal composite fuel prepared in the embodiments 6 to 10 has the dry basis moisture content of 0.9 to 1.1 percent, the dry basis volatile component of 15.2 to 17.4 percent, the dry basis ash content of 6.2 to 8.2 percent, the dry basis calorific value of 28.6MJ to 29.2MJ, the sample sulfur content of 0.23 to 0.31 percent, the alkali metal content of 0.07 to 0.09 percent, the ash melting point of 1322 to 1388 ℃ and the Hawski grindability index of 67.2 to 72.6 percent, and meets the requirements of a blast furnace coal powder injection process on the components, the heat value, the harmful element content and the medium-speed grinding powder. As can be seen from Table 4, the biomass charcoal composite fuel prepared under different conditions has slightly different components and blast furnace injection process performance, but can meet the requirement of blast furnace injection, can be used as a substitute fuel of blast furnace injection pulverized coal, and can reduce the consumption of fossil fuel in iron-making production.

Examples 11 to 14

Examples 11 to 14 provide biomass char composite fuels for blowing into a biomass blast furnace, which are different from example 3 in the molding pressure and molding time used, and specific values for each example are shown in table 5. The other preparation methods are substantially the same as those of example 3, and are not repeated herein. Table 6 shows the properties of the biomass charcoal composite fuel prepared in examples 11 to 14.

TABLE 5 Molding pressures and Molding times for examples 11 to 14

Examples	Forming pressure (MPa)	Molding time (min)
			Example 11	60	0.1
Example 12	30	0.5
			Example 13	30	1
Example 14	10	3

Table 6 Performance of biomass charcoal composite fuel prepared in examples 11-14

Examples	Example 11	Example 12	Example 13	Example 14
					Bulk Density (g/cm)³)	2.29	2.31	2.35	2.16
Molding ratio (%)	86	92	94	75
					Compressive strength (MPa)	0.21	0.17	0.18	0.13
Moisture (%)	1.3	1.4	1.4	1.5
					Dry basis volatiles (%)	17.0	16.9	16.9	16.8
Dry basis ash (%)	6.9	6.8	6.9	7.0
					Heating value of drying base (MJ/kg)	29.0	29.2	29.1	29.2
Sulfur content (%)	0.27	0.27	0.27	0.27
					Alkali Metal (K + Na) (%)	0.08	0.08	0.08	0.08
Ash melting Point (. degree. C.)	1336	1335	1136	1337
					Ha's grindability index (%)	68.3	71.7	70.5	72.6

As can be seen from table 6, the molding pressure and the molding time have significant effects on the properties of the prepared biomass charcoal composite fuel, especially have the greatest effects on the bulk density and the molding rate, and the bulk density is continuously increased along with the increase of the molding pressure, the molding rate is increased, and the compressive strength is enhanced; the volume density and the forming rate can be increased by prolonging the forming time, and the compressive strength is improved to a certain extent. The molding pressure and the molding time have little influence on moisture, volatile matters, ash content, calorific value, sulfur content and alkali metal content, and the ash melting point has no great change. With the reduction of the forming pressure and the shortening of the forming pressure, the Hawthorn millable index of the biomass charcoal composite fuel is slightly increased. Therefore, the composite hydrothermal carbon and the high-metamorphic coal are mixed and hot-pressed, so that the performance of the composite fuel is improved, and the milling, pipeline conveying and injection performance of the mixed fuel is improved.

Examples 15 to 17

Examples 15 to 17 provide biomass char composite fuel for biomass blast furnace injection, which is different from example 3 in the biomass raw material used, and the specific values for each example are shown in table 7. The other preparation methods are substantially the same as those of example 3, and are not repeated herein. Table 8 shows the properties of the biomass charcoal composite fuel prepared in examples 15 to 17.

TABLE 7 Biomass feedstock types corresponding to examples 15 to 17

Table 8 Performance of biomass charcoal composite fuel prepared in examples 15-17

Examples	Example 15	Example 16	Example 17
				Bulk Density (g/cm)³)	2.15	2.63	2.38
Molding ratio (%)	96	97	97
				Compressive strength (MPa)	2.2	2.4	2.5
Moisture (%)	1.5	1.2	1.3
				Dry basis volatiles (%)	17.2	15.1	16.1
Dry basis ash (%)	7.8	6.2	5.8
				Heating value of drying base (MJ/kg)	27.4	32.3	31.3
Sulfur content (%)	0.28	0.23	0.21
				Alkali Metal (K + Na) (%)	0.08	0.07	0.07
Ash melting Point (. degree. C.)	1375	1386	1371
				Ha's grindability index (%)	71.2	73.9	72.3

As can be seen from table 8, the biomass charcoal composite fuel prepared in examples 15 to 17 can meet the requirement of blast furnace injection smelting, wherein the biomass charcoal composite fuel prepared when the palm shells are biomass raw materials has the best performance, the ash content is only 6.2%, the calorific value reaches 32.3MJ/kg, the sulfur content is 0.23%, the alkali metal content is only 0.07%, the ash melting point reaches 1386 ℃ and the hastelloy index reaches 73.9%, and can meet the requirement of blast furnace smelting on the quality of the injection fuel.

Comparative example 1

Comparative example 1 provides a biomass charcoal composite fuel for blowing of a biomass blast furnace, which is different from example 3 in that the biomass is subjected to hydrothermal carbonization and then mixed with low-metamorphic coal for heat preservation. The rest is substantially the same as embodiment 3, and will not be described herein.

TABLE 9 COMPARATIVE EXAMPLE 1 preparation of Biomass charcoal composite Fuel Properties

As can be seen from Table 9, the biomass charcoal composite fuel prepared in comparative example 1 has lower volume density, molding rate and compressive strength than those of example 3; the biomass composite fuel prepared in the comparative example 1 has higher moisture content, volatile content and ash sulfur content than those of the biomass composite fuel prepared in the example 3, and has a lower calorific value; comparative example 1 also contained a higher alkali metal content, a lower ash melting point and a harshness grindability index. In the comparative example 1, the forming rate of only 85 percent can not meet the requirement of industrial production of the biomass charcoal composite fuel, the alkali metal content reaches 0.15 percent, and the requirement of blast furnace injection on the alkali metal content of the fuel can not be met. Thus, the present invention can produce significant beneficial effects by hydrothermally carbonizing low metamorphic coal with biomass.

Although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the spirit and scope of the present invention.

Claims

1. a preparation method of biomass carbon composite fuel for blast furnace injection, is characterized in that, comprises the following steps:

S1. Mix the crushed biomass raw material and low-metamorphic coal according to a preset mass ratio, and then perform hydrothermal carbonization treatment together to obtain composite hydrothermal carbon;

S2. Preheat the crushed highly metamorphic coal, then mix with the composite hydrothermal char obtained in step S1 according to a preset mass ratio, and keep the heat at a preset temperature, and then hot-press molding to obtain the blast furnace injection Combining fuel with biomass charcoal.

2 . The method for preparing a biomass-charcoal composite fuel for blast furnace injection according to claim 1 , wherein, in step S1 , the preset mass ratio of the biomass to the low-metamorphic coal is (85-95) 2 . : (5 to 15).

3 . The preparation method of biomass carbon composite fuel for blast furnace injection according to claim 1 , wherein, in step S1 , the temperature of the hydrothermal carbonization treatment is controlled at 220-350° C., corresponding to the saturated vapor pressure. 4 . It is 2.3～16.5MPa, and the treatment time is controlled at 0.5～3h.

4 . The preparation method of biomass charcoal composite fuel for blast furnace injection according to claim 1 , wherein in step S2 , the highly metamorphic coal is preheated to 650-700° C. in a heating furnace, and the composite The temperature of the hydrothermal charcoal is controlled at 80-250°C.

5. The preparation method of biomass carbon composite fuel for blast furnace injection according to claim 1, characterized in that, in step S2, the composite hydrothermal carbon and the preheated high metamorphic coal are in a weight ratio of (30～ 90): (10～70) After mixing, the temperature is controlled at 300～450℃ and kept warm.

6 . The method for preparing biomass carbon composite fuel for blast furnace injection according to claim 1 , wherein, in step S2, the temperature of the hot pressing is 300-450° C., the pressure is 10-60 MPa, and the time It is 0.1～3min.

7. The preparation method of biomass-charcoal composite fuel for blast furnace injection according to claim 1, wherein the biomass includes but is not limited to a kind of agricultural waste, forestry waste, and urban organic waste or a mixture of several biomass, the low-metamorphic coal includes but is not limited to a mixture of one or more of cohesive gas coal, fat coal, coking coal, lean coal, lean lean coal; Metamorphic coal includes, but is not limited to, one or a mixture of anthracite, blue carbon, upgraded coal, coke, and carbon black.

8 . The method for preparing biomass-charcoal composite fuel for blast furnace injection according to claim 1 , wherein the particle sizes of the biomass, low-metamorphic coal and high-metamorphic coal after crushing are all 0-3 mm. 9 .

9 . The method for preparing the biomass charcoal composite fuel for blast furnace injection according to claim 1 , wherein the bulk density of the biomass charcoal composite fuel for blast furnace injection is 0.9-2.5 g/cm ³ , and the The compressive strength is ≥0.1MPa, the diameter is 8-30mm, and the particle or columnar fuel with the aspect ratio is 1-6, and the molding rate is ≥95%; Base fixed carbon ≥ 65%, calorific value ≥ 26MJ/kg, sulfur content ≤ 0.3%, alkali metal (K+Na) ≤ 0.1%, ash melting point ≥ 1200 ℃, Hastelloy grindability index ≥ 60%.

10 . The preparation method of biomass charcoal composite fuel for blast furnace injection according to claim 1 , wherein the biomass charcoal composite fuel for blast furnace injection is broken during use and mixed with pulverized coal for blast furnace injection. 11 . .