About Sameer Usmani

Sameer Usmani is an environmental researcher and a PhD student at Australian National University, Australia. His research work revolves around renewable energy (biomass, solar), material analysis. He has expertise in simulation software viz. Aspen Plus, UniSim, MATLAB and completed/working range of projects for industrial projects. Sameer has several publications in respected journals, proving his competency and expertise with numerical modelling and experimental works. If you are interested to know more about his work, you can reach him at sameer.usmani.me@gmail.com/sameer.usmani@anu.edu.au

Green Steel Production – Opportunities and Challenges

The steel manufacturing industry is one of the highest carbon emission sources globally, leading to the highest CO2 emissions into the atmosphere. The process from converting iron ore to graded steel includes a blast furnace, followed by a basic oxygen furnace and an electric arc furnace. The highest emissions are generated during coke production, blast furnace, i.e., Energy demand and GHG emissions in the Iron and Steel sector principally result from the large consumption of coal/coke used in conjunction with the blast furnace.

What is Green Steel

Green steel refers to the process of steel manufacturing with reduced GHG emissions into the atmosphere as well as potentially reducing cost and improving steel quality, as compared to conventional steel production. A study indicates that steel demand will keep on rising until the end of the 21st century, so there is a huge motivation to look for an alternative method of steel production that emits low greenhouse gas (GHG) emissions into the atmosphere.

what is green steel

Scrap steel recycling is a positive step toward alleviating emissions. However, based on the available scrap, this route can contribute 44% of the total steel production by the end of 2050, which is not sufficient to meet the growing demands.

Also, the issue with recycled steel is that they are contaminated with copper and tin, which causes surface cracking during the hot rolling process. An integrated steel recycling process with innovative routes can bring down the global warming to a manageable threat.

Blast furnace (BF) and basic oxygen furnace (BOF) contribute to 70% of total GHG emissions into the environment. The process reduces iron into ores, sinter and pellets using carbon-based lowering agents. Fluxes (or steel scrap) are added to the blast furnace to maintain the slag temperature and separate the impurities. The hot metal produced contains sulphur, phosphorous, manganese and silicon. The impurities are heated/reduced in BOF to produce high-quality steel with carbon below 2%.

According to research, hydrogen-based and electricity-based steel production have minimal emissions into the atmosphere. However, this technology is still under investigation, some small-scale development has been done in the past, but large scale development is still under development phase.

Pathways for Green Steel Production – Opportunities and Challenges

Various alternative ways exist to produce low-grade carbon products such as carbon capture and storage (CCS), renewable hydrogen and high utilisation of biomass resources. The use of artificial iron units (AIUs) in iron steel production can reduce significant carbon emissions and high-grade steel production.

To minimize emissions, scrap use must be incorporated into the manufacturing process. The use of bioenergy resources in steel production can be a good option, but that goes through a long list of concerns, such as biomass availability, the capital cost of replacement of existing technology.

An Integrated Iron and Steel Mill (ISM) consists of many complex series of interconnected plants, where emissions come out from many sources (10 or more). Huge amount of CO2 is produced by the reduction reaction reactions occurring in the blast furnace and the combustion reaction in sintering, blast furnace and basic oxygen furnace.

green steel

Biomass can be used for steel production in place of coal, but this is discouraged by most industries, mainly because of huge biomass requirement, transportation, and storage requirement. Another alternative is the use of natural gas, which at present accounts for 20% of overall steel production in the world. Natural gas produces GHG emissions, which is feasible for small scale goals. If the end target is to achieve significant scale goals, then natural gas use integrated with carbon capture technology is beneficial.

The absorption process is another method used to separate CO2 from gas streams using chemical solvents. However, this process is very expensive because of the high thermal energy required to break the strong bond between solvents and CO2.

Adsorption is also a process to reduce CO2 where a gas stream is passed through the solid adsorbent (such as zeolites, activated carbon). The bed loaded with reduced pressure, increased temperature, and low voltage electric current is challenging to maintain to also expensive.

Gas separation is also a method to reduce GHG emissions, which works on the development of gas separation membranes (polymers, ceramics, zeolites and metals), depending on the difference in physical and chemical interactions. The reducing efficiency reaches up to 80% CO2 separation. In 2007, a simulation study revealed 97% of CO2 recovery from blast furnace gas. Ongoing research in Australia where researchers are developing new technology for gas separation membrane. The research aims to test a number of separation strategies, investigate the influence of syngas and minor gas components.

Hydrogen-based steel making route is another positive step toward green steel. Two different routes exist, direct hydrogen reduction and hydrogen plasma reduction. Small scale utilisation of hydrogen with up to 70% volume reduction was achieved, but the large-scale application is still under development.

The challenge lies mostly with the hydrogen-based DRI process, it produces 0% carbon which does not fulfil the carbon demand of the downstream process. The second issue is the supply of sufficient hydrogen. According to the study, the electricity cost for hydrogen production, considering the electrolysis to produce the hydrogen, should be less than 0.02 USD/kWh to make the process economically feasible. However, hydrogen storage supply and transportation costs are other scopes that still need to be explored.

Closing Comments

As on closing comments, steel production is one of the highest GHG emitting sources globally. If not controlled, the commitment at Paris Climate Summit 2015 to hold global temperature below 2℃ seems lost way before the set target date of 2050.

Promoting green steel production can be majorly significant with the targets. Technologies exist that can reduce GHG emissions, and some of them are under commission at a small scale; however, large scale implementation is yet to get approval from research integrity.

Existing technologies are very expensive, or they do have technical challenges which are economically costly to manage. Hydrogen-based steel production is a technology that looks very promising. Researchers are working on the project to analyse the economic and technical feasibility at a large scale.

Everything You Need to Know About Carbon Black

Carbon Black is a commercial form of solid carbon that is manufactured in highly controlled processes to produce specifically engineered aggregates of carbon particles that vary in particle size, aggregate size, shape, porosity and surface chemistry. Carbon Black typically contains more than 95 % pure carbon with minimal quantities of oxygen, hydrogen and nitrogen.

In the manufacturing process, Carbon Black particles range from 10 nm to approximately 500 nm in size. These fuse into chain-like aggregates, which define the structure of individual Carbon Black grades.

What is Carbon Black

Carbon Black is used in a diverse group of materials in order to enhance their physical, electrical and optical properties. Its largest volume use is as a reinforcement and performance additive in rubber products.

In rubber compounding, natural and synthetic elastomers are blended with Carbon Black, elemental sulphur, processing oils and various organic processing chemicals, and then heated to produce a wide range of vulcanized rubber products. In these applications, Carbon Black provides reinforcement and improves resilience, tear-strength, conductivity and other physical properties.

Carbon Black is the most widely used and cost effective rubber reinforcing agent (typically called Rubber Carbon Black) in tire components (such as treads, sidewalls and inner liners), in mechanical rubber goods (“MRG”), including industrial rubber goods, membrane roofing, automotive rubber parts (such as sealing systems, hoses and anti-vibration parts) and in general rubber goods (such as hoses, belts, gaskets and seals).

Applications of Carbon Black

Besides rubber reinforcement, Carbon Black is used as black pigment and as an additive to enhance material performance, including conductivity, viscosity, static charge control and UV protection. This type of Carbon Black (typically called Specialty Carbon Black) is used in a variety of applications in the coatings, polymers and printing industries, as well as in various other special applications.

Actually, after oil removal and ash removal processing from tire pyrolysis, we can get high-purity commercial carbon black, which can be used to make color masterbatch, color paste, oil ink and as addictive in plastic and rubber products. Besides, after activation treatment, the carbon black will become good materials to produce activated carbon.

In the coatings industry, treated fine particle Carbon Black is the key to deep jet black paints. The automotive industry requires the highest black intensity of black pigments and a bluish undertones.

Carbon Black has got a wide array of applications in different industries

Small particle size Carbon Blacks fulfill these requirements. Coarser Carbon Blacks, which offer a more brownish undertone, are commonly used for tinting and are indispensable for obtaining a desired grey shade or color hue.

In the polymer industry, fine particle Carbon Black is used to obtain a deep jet black color. A major attribute of Carbon Black is its ability to absorb detrimental UV light and convert it into heat, thereby making polymers, such as polypropylene and polyethylene, more resistant to degradation by UV radiation from sunlight. Specialty Carbon Black is also used in polymer insulation for wires and cables. Specialty Carbon Black also improves the insulation properties of polystyrene, which is widely used in construction.

In the printing industry, Carbon Black is not only used as pigment but also to achieve the required viscosity for optimum print quality. Post-treating Carbon Black permits effective use of binding agents in ink for optimum system properties. New Specialty Carbon Blacks are being developed on an ongoing basis and contribute to the pace of innovation in non-impact printing.

Applications of Biochar

Biochar is a carbon-rich, fine-grained residue which can be produced either by ancient techniques (such as covering burning biomass with soil and allowing it to smoulder) or state-of-the-art modern biomass pyrolysis processes. Combustion and decomposition of woody biomass and agricultural residues results in the emission of a large amount of carbon dioxide. Biochar can store this CO2 in the soil leading to reduction in GHGs emission and enhancement of soil fertility. Biochar holds the promise to tackle chronic human development issues like hunger and food insecurity, low agricultural productivity and soil depletion, deforestation and biodiversity loss, energy poverty, water pollution, air pollution and climate change. Let us have a close look at some of the most promising applications of biochar.


Use of biochar in animal farming

At present approx. 90% of the biochar used in Europe goes into animal farming. Different to its application to fields, a farmer will notice its effects within a few days. Whether used in feeding, litter or in slurry treatment, a farmer will quickly notice less smell. Used as a feed supplement, the incidence of diarrhoea rapidly decreases, feed intake is improved, allergies disappear, and the animals become calmer.

In Germany, researchers conducted a controlled experiment in a dairy that was experiencing a number of common health problems: reduced performance, movement disorder, fertility disorders, inflammation of the urinary bladder, viscous salivas, and diarrhoea. Animals were fed different combinations of charcoal, sauerkraut juice or humic acids over periods of 4 to 6 weeks.

Experimenters found that oral application of charcoal (from 200 to 400 g/day), sauerkraut juice and humic acids influenced the antibody levels to C. botulinum, indicating reduced gastrointestinal neurotoxin burden. They found that when the feed supplements were ended, antibody levels increased, indicating that regular feeding of charcoal and other supplements had a tonic effect on cow health.

Biochar as soil conditioner

In certain poor soils (mainly in the tropics), positive effects on soil fertility were seen when applying untreated biochar. These include the higher capacity of the soil to store water, aeration of the soil and the release of nutrients through raising the soil’s pH-value. In temperate climates, soils tend to have humus content of over 1.5%, meaning that such effects only play a secondary role.

Indeed, fresh biochar may adsorb nutrients in the soil, causing at least in the short and medium term – a negative effect on plant growth. These are the reasons why in temperate climates biochar should only be used when first loaded with nutrients and when the char surfaces have been activated through microbial oxidation.

The best method of loading nutrients is to co-compost the char. This involves adding 10–30% biochar (by volume) to the biomass to be composted. Co-composting improves both the biochar and the compost. The resulting compost can be used as a highly efficient substitute for peat in potting soil, greenhouses, nurseries and other special cultures.

Because biochar serves as a carrier for plant nutrients, it can produce organic carbon-based fertilizers by mixing biochar with such organic waste as wool, molasses, ash, slurry and pomace. These are at least as efficient as conventional fertilizers, and have the advantage of not having the well-known adverse effects on the ecosystem. Such fertilizers prevent the leaching of nutrients, a negative aspect of conventional fertilizers. The nutrients are available as and when the plants need them. Through the stimulation of microbial symbiosis, the plant takes up the nutrients stored in the porous carbon structure and on its surfaces.
A range of organic chemicals are produced during pyrolysis. Some of these remain stuck to the pores and surfaces of the biochar and may have a role in stimulating a plant’s internal immune system, thereby increasing its resistance to pathogens. The effect on plant defence mechanisms was mainly observed when using low temperature biochars (pyrolysed at 350° to 450°C). This potential use is, however, only just now being developed and still requires a lot of research effort.

Biochar as construction material

The two interesting properties of biochar are its extremely low thermal conductivity and its ability to absorb water up to 6 times its weight. These properties mean that biochar is just the right material for insulating buildings and regulating humidity. In combination with clay, but also with lime and cement mortar, biochar can be added to clay at a ratio of up to 50% and replace sand in lime and cement mortars. This creates indoor plasters with excellent insulation and breathing properties, able to maintain humidity levels in a room at 45–70% in both summer and winter. This in turn prevents not just dry air, which can lead to respiratory disorders and allergies, but also dampness and air condensing on the walls, which can lead to mould developing.

As per study by the Ithaka Institute’s biochar-plaster wine cellar and seminar rooms in the Ithaka Journal. Such biochar-mud plaster adsorbs smells and toxins, a property not just benefiting smokers. Biochar-mud plasters can improve working conditions in libraries, schools, warehouses, factories and agricultural buildings.

Biochar is an efficient adsorber of electromagnetic radiation, meaning that biochar-mud plaster can prevent “electrosmog”. Biochar can also be applied to the outside walls of a building by jet-spray technique mixing it with lime. Applied at thicknesses of up to 20 cm, it is a substitute for Styrofoam insulation. Houses insulated this way become carbon sinks, while at the same time having a more healthy indoor climate. Should such a house be demolished at a later date, the biochar-mud or biochar-lime plaster can be recycled as a valuable compost additive.

Biochar as decontaminant

As a soil additive for soil remediation – for use in particular on former mine-works, military bases and landfill sites.

Soil substrates – Highly adsorbing and effective for plantation soil substrates for use in cleaning wastewater; in particular urban wastewater contaminated by heavy metals.

A barrier preventing pesticides getting into surface water – berms around fields and ponds can be equipped with 30-50 cm deep barriers made of bio-char for filtering out pesticides.

Treating pond and lake water – bio-char is good for adsorbing pesticides and fertilizers, as well as for improving water aeration.

Use of biochar in wastewater treatment – Our Project

The biochar grounded to a particle size of less than 1.5 mm and surface area of 600 – 1000 m2/g. The figure below is the basic representation of production of bio-char for wastewater treatment.

We conducted a study for municipal wastewater which was obtained from a local municipal treatment plant. The municipal wastewater was tested for its physicochemical parameters including pH, chemical oxygen demand (COD), total suspended solids (TSS), total phosphates (TP) and total Kjeldahl nitrogen (TKN) using the APHA (2005) standard methods.

Bio filtration of the municipal wastewater with biochar acting as the bio adsorbent was allowed to take place over a 5 day period noting the changes in the wastewater parameters. The municipal wastewater and the treated effluent physicochemical.

The COD concentration in the municipal wastewater decreased by 90% upon treatment with bio-char. The decrease in the COD was attributed to the enhanced removal of bio contaminants as they were passed through the bio char due to the bio char’s adsorption properties as well as the high surface area of the bio char. An 89% reduction in the TSS was observed as the bio filtration process with bio char increased from one day to five days

The TKN concentration in the wastewater decreased by 64% upon treatment with bio char as a bio filter. The TP in the wastewater decreased by 78% as the bio filtration time with bio char increase. The wastewater pH changed from being alkaline to neutral during the treatment with bio char over the 5 day period

Use in Textiles

In Japan and China bamboo-based bio-chars are already being woven into textiles to gain better thermal and breathing properties and to reduce the development of odours through sweat. The same aim is pursued through the inclusion of bio-char in shoe soles and socks.