carbon emission

Main Measures to Reduce Carbon Emission in the Steel Industry

The steel industry is a representative of energy-intensive industries and a pillar industry in the industrial system. The steel industry is highly related to upstream and downstream industries. When industries such as real estate, automobiles, machinery, and construction grow, society’s demand for steel also increases. At the same time, steel production has also driven the growth of industrial scale in upstream mining, transportation and other industries. As an important link in the path of industrial production, the scale growth of the steel industry relies on and demonstrates the rapid development of China’s economy. In addition, as a labor-intensive production industry, the steel industry also plays a key role in stimulating local consumption and stabilizing the employment situation.

Steel Industry Carbon Footprint

The current mainstream steel smelting process is generally divided into two categories: long-process steelmaking that includes the iron-making process and short-process steelmaking that does not include the iron-making process and uses scrap steel as the main raw material.

The steel industry requires a large amount of outsourced energy to support the normal operation of large power consumers such as blast furnace blowers, electric furnaces, and refining furnaces. The rolling and post-processing processes also require electricity to maintain the operation of rolling mills, electroplating and other process equipment. Although the iron and steel smelting process usually uses waste heat and pressure to generate electricity, about 50% of the power demand still needs to be met by purchased power. The indirect carbon emissions caused by this part of the electricity are Scope 2 emissions. Based on China’s annual steel production of 1 billion tons, the steel industry will produce approximately 240 million tons of scope 2 emissions of carbon dioxide equivalent every year.

The main measures of carbon reduction in the steel industry

1. Scrap utilization

After comparing the long process and short process steel making, we can find that the carbon emission of short process steel making is only about 1/3 of that of long process steel making. Carbon emissions are mainly from the reduction process of high-priced iron, so making more use of scrap steel and reducing the amount of reduction reaction is a powerful measure to reduce carbon.

In the context of carbon emission reduction, the intensive collection and treatment of scrap is an inevitable trend under the incentive of the market, at the same time, the preferential tax policy of scrap treatment is landed, and the policy of scrap import is opened, which is also the key to fill the short board of scrap supply and reduce the procurement cost of scrap.

2. Improved energy efficiency

The energy efficiency improvement of steelmaking enterprises is mainly focused on the full use of self-generated heat energy, pressure and fuel. The technology of energy efficiency improvement has been relatively mature, and steelmaking enterprises can quickly use it, such as the dry quenching technology of coke oven, the waste heat utilization technology of sintering, the gas residual pressure turbine power generation technology of blast furnace, the gas recovery technology of converter, the scrap preheating technology of electric furnace, and the annealing preheating technology of rolled steel. Energy efficiency improvement mostly involves fixed asset investment projects, iron and steel enterprises in the capacity replacement at the same time, energy consumption, carbon emissions reduction into the new replacement capacity planning, promote the construction of energy efficiency improvement facilities.

3. Sustainable energy

As energy companies strive to put sustainable energy into the market and reduce carbon emissions in the energy industry, steel companies should simultaneously promote the use of sustainable energy, such as expanding electric furnace steelmaking production. This also requires steel companies to make predictions about scrap steel and carbon reduction policies, and plan the construction of electric furnace steelmaking capacity in advance.

4. Fuel replacement

In long-process steelmaking, the main fuels are fossil fuels such as coal and natural gas. The use of low-carbon fuels to replace coal already has mature applications, such as reducing the proportion of sinter entering the furnace, using biomass fuel to replace part of the coal, and using hydrogen as a reducing agent in blast furnace steelmaking. These applications can effectively reduce carbon emissions. The above three technologies alone can reduce carbon dioxide emissions by approximately 204 kilograms per ton of steel.

5.CCUS

The application of “blast furnace + carbon capture” technology in the steel industry is mainly carried out in conjunction with traditional smelting technology to capture the carbon that escapes from large carbon emitters (such as blast furnaces). At present, the application of carbon capture technology that has developed rapidly is the process route of “blast furnace + carbon capture” and “melting furnace + carbon capture”.

The carbon emissions produced by the blast furnace account for about 1/3 of the carbon emissions of the entire long-process steelmaking. Carbon capture or storage technology can reduce the carbon released by blast furnaces by solidifying gaseous carbon dioxide and storing it in underground storage devices or converting it into other chemicals. The route of converting carbon dioxide into hydrocarbons can effectively reduce carbon dioxide emissions by 80%. However, carbon capture technology is still in the early trial stage in traditional processes and has not been applied on a large scale.

Smelting furnace is the use of iron ore, coal directly reduction iron making, eliminating the sintering process, which is a major carbon emission, directly reduce the carbon emission in the process of iron making. The current mature smelting furnace ironmaking technology is COREX, which is a technology developed by Voestelian that uses large blocks of iron ore and coal to smelt directly, eliminating the sintering process and also eliminating the coking process of converting coal into coke. Baowu Group successfully built and put into operation COREX furnace in Bayi Steel Plant. However, COREX furnace also has its delicate place, that is, the quality requirements of ore and coal are high, and the melting process itself will still have carbon emissions, which need to be captured and neutralized with carbon capture technology.

Another smelting furnace steelmaking technology that is still in its early stages is Tecnored, which uses biomass energy. Tecnored is a technology developed with the support of Brazilian company Vale that uses sugar cane to make biomass energy for the reduction reaction in the smelting process, while the carbon dioxide produced during the melting process can be “consumed” by the cultivated sugar cane, thus achieving carbon neutrality in the steel production value chain.

6. Carbon substitution technology

Compared with carbon capture technology, carbon substitution technology fundamentally replaces the application of carbon elements in the production process to achieve true carbon neutrality. As far as iron and steel smelting is concerned, the current technical direction is mainly focused on direct reduced iron technology and electrolysis smelting. The direct reduced iron technology is to use combustible gas and pellets to smelt sponge iron with less impurities and low carbon content for electric furnaces. Compared with traditional blast furnace ironmaking, it can reduce carbon dioxide emissions by 50%. At present, the technology of direct reduction smelting with natural gas is mature, but it requires high quality of pellets, and the consumption of natural gas is huge, and the production cost is higher than that of traditional blast furnace ironmaking.

The smelting technology that uses hydrogen energy for direct reduction is still under development. Its core is to use hydrogen as a reducing agent to reduce pellets. Limited by the current cost of hydrogen energy, large-scale smelting test facilities are still in the construction stage.

Another carbon replacement technology is electrolytic iron. Electrolytic iron technology can effectively reduce carbon dioxide emissions by about 87%, but it is still in its infancy. The smelting process of some non-ferrous metals such as copper, aluminum and high-value ferrous metal manganese uses electrolysis. The electrolysis method is suitable for producing metal elements, but the cost is relatively high. Some technology companies such as BOSTON METAL are working to reduce the production costs of electrolysis and make it a viable ironmaking process.