Iron-and-steel industry

Air and gas cleaning procedures in iron-and-steel industry: methods and equipment

The manufacturer and supplier of advanced gas treatment facilities PZGO LLC offers to calculate, design, manufacture and put into operation air control and purification equipment for metallurgical industries: particulate and dust catchers, exhaust scrubber systems, chemical absorbers and flue / blast-furnace gas cleaners.

We have been closely cooperating with Russian and foreign metallurgical enterprises for over 30 years. Over these decades, we thoroughly investigated all aspects of iron-and-steel branch and developed methods and equipment that made it possible to achieve almost 100% reduction of harmful / toxic and undesirable gaseous and mechanical emissions.

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Types of harmful emissions connected with the production of steel and cast iron

Steels and cast irons, without exaggeration, are the most important structural materials of the modern world. Due to the hardness and endurance, steel is used in almost every household item, as well as in machine parts and mechanisms.

Of course, such a demand for metal products causes a steady increase in smelting output. In 2018, the production of steel and iron increased by 4.6% (in comparison with 2017) and amounted to 1.8 billion tons.

It should be borne in mind that the end product of the ferrous metallurgy is only a 15-40 % of the feedstock (depending on the grade of steel or cast iron).

Thus, it is easy to calculate that the annual volume of the processed charge / blast furnace burden amounts to tens of billions of tons. This figure becomes even more frightening when you consider that a significant part of this volume eventually turns into hazardous gaseous and mechanical waste.

Emission components Presence / Amount, kilograms per ton
Mechanical dust up to 106
Carbonic oxide up to 50
Sulphur oxides up to 25
Nitrogen oxides up to 3
Hydrogen sulphide up to 60
Aerosols etching rooms
Vapors / Emulsions metal processing procedures

Fortunately, environmental organizations are constantly tightening the requirements for emissions (flue gases, exhaust smokes and fumes) of enterprises, so the industrialists are increasingly concerned about the installation of efficient gas and air cleaning systems (wet scrubber systems, absorbers, adsorption towers, Venturi dust collectors, furnace gas cleaners, etc.).

Gas cleaning activities in the context of steel and cast iron smelting

The main methods for the production of steel today are: oxygen-blow process, open-hearth (also known as Siemens-Martin) method, and electric steelmaking.

All these approaches have their advantages. But, unfortunately, they are also not without flaws, which consist, among other things, in the formation of tangible volumes of harmful substances.

However, before proceeding to the production of steel, it should be noted that the precursor for its production is always steel-making pig iron. Cast / pig iron (in 90% of cases) is produced by melting iron-containing ores or agglomerated feedstocks in a blast furnace at temperatures above 1000 degrees Celsius.

The main “fuel” for blast furnaces is coke, but to intensify the combustion, natural gas, fuel oil or coal dusts are often added to the tuyere.

During combustion, the above hydrocarbon fuel generates a wide range of harmful gases and ash (soot), which is subject to mandatory neutralization. The most effective device to deactivate flue / blast-furnace emissions after burning organic fuel is fluidized bed scrubber. Read more about floating bed scrubber systems.

Oxygen-blow process / basic oxygen furnace process

The principle of this production method is in the title itself. Pig iron is loaded into the converter, heated to a liquid state and blown through an oxygen stream.

Currently, about 60% of all steel in the world is manufactured by the oxygen blow method. Carbon, silicon, manganese and other elements in the pig iron are oxidized and removed from the melt, so that the iron is transformed into steel.

venturi scrubber for steel industry

Venturi scrubber for collecting metal dust (emissions from smelting vessel), produced at PZGO LLC

An important consumable element of the converter is the chemically active lining. In experimental converters, the lining life is about 2500 cycles. As the converter works, the lining burns out, increasing the concentration of enough already harmful emissions from the basic oxygen furnace.

Depending on the type of oxygen converter, maximum efficiency in trapping unwanted gases (and parallel cooling of the stream) can be shown by a fluidized bed scrubber, an orifice / foam or packed absorber.

Please describe your converter / furnace and clarify the conditions of technological processes, and we will calculate the characteristics of the equipment that will be necessary and sufficient to perform the required gas cleaning / air purification tasks.

Open-hearth method

The open-hearth furnace is one of the pioneers of steelmaking equipment. The first working furnace was created by Pierre Martin in 1864 and for a long time the open-hearth method was the main approach to the creation of steel.

But progress does not stand still, and since the middle of the last century, the replacement of open-hearth furnaces with more modern electric furnaces began. The emissions of gases and slag generated by these units are prohibitively high, but, fortunately, today it no longer matters.

To date, the amount of steel produced by the open-hearth method is no more than 2%, and the working furnaces remain only in Ukraine and in India. Open-hearth furnaces have made a significant contribution to the development of human civilization, but today they are mainly of historical interest.

Electric steelmaking

Electric steelmaking is the most advanced approach to the smelting of high-quality and high-alloy steels, the production of which is impossible neither in open-hearth furnaces nor in oxygen converters. In addition, electric arc furnaces have ≈ 7 times higher productivity than open-hearth furnaces.

But, leaving behind the benefits of these units, we turn to the operation of furnaces in the context of air and gas cleaning procedures. The main source of steel is scrap (charge), which in addition to ore concentrates contains fuel, usually coal, pitch, torus or petroleum coke. Coke burning implies the emission of a spectrum of gaseous and gas-mechanical components characteristic of any organic matter. These are sulfur oxides, nitrogen oxides, acids, benzenes and other products of thermal decomposition of hydrocarbon fuels.

column type packed absorber

Column-type packed absorber for neutralizing toxic / unwanted gaseous and aerosol pollutants

Among other things, electric arc furnaces are capable of producing high-alloy steels, in which chromium, nickel, silicon, molybdenum, niobium, cobalt, boron, and many other metals and non-metals are used as alloying elements.

The combination of the above substances (coke combustion products and alloying elements) at high temperatures can mother a virtually unlimited number of gas conglomerates, many of which are very likely to exhibit reactive / toxic properties.

FBS air pollution control systems

The main type of gas cleaning equipment, which is capable of simultaneously trapping all gases and dust showing reactivity, is a wet fluidized bed scrubber.

The main advantages of these systems are: high flexibility, construction simplicity, easy maintenance, efficiency at capturing complex pollutants is 96-99%, cooling of gas flow being processed, mechanical self-cleaning feature, and fully automatic performance within operation and sludge removal.

Fluid bed movement (demo stand)

We have described in detail all the advantages of these apparatuses on a separate page. Please review the full list of FBS specifications.

To expand and increase the productivity of the air pollution control infrastructure, the scrubbers can be combined into a chain with absorption and adsorption columns, which will bring the cleaning level to ≈ 100%.

Calculation, design and manufacture of gas treatment plants for metallurgical enterprises in Europe and Asia

Please do not focus blindly on the reference information provided on this page. Every single production needs a unique approach.

To discuss the conditions for the individual design and manufacture of unique, durable and inexpensive equipment for your metallurgical enterprise, please fill in the Customer's questionnaire or contact PZGO LLC in any convenient way.

We are ready to quickly deliver gas treatment plants to anywhere in Europe and Asia and, if necessary, conduct a training course for personnel and put equipment into operation.

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