Air emissions profile: Which set lists the most common primary pollutants released by the iron and steel industry?

Introduction / Context:
Integrated iron and steel plants emit a characteristic set of pollutants from sinter plants, coke ovens, blast furnaces, basic oxygen furnaces, and reheating furnaces. Knowing the typical pollutants helps target control technologies and comply with environmental regulations.

Given Data / Assumptions:

• Typical fuels: coke oven gas, blast furnace gas, natural gas, and auxiliary liquid fuels.
• High-temperature thermal processes with combustion and reduction reactions.
• Focus on primary gaseous pollutants, not particulate or metals.

Concept / Approach:
Carbon monoxide (CO) and carbon dioxide (CO2) arise from combustion and reduction reactions (CO as a reductant in blast furnaces). Sulfur dioxide (SO2) primarily originates from sulfur in coke and heavy fuels. While nitrogen oxides (NOx) may also be present, the question asks for the main pollutants traditionally associated with the sector, prominently CO/CO2/SO2.

Step-by-Step Solution:
1) Evaluate CO: Produced in large quantity in BFs and combustion systems; significant pollutant and energy carrier.2) Evaluate CO2: Unavoidable product of oxidation and calcination; major greenhouse gas.3) Evaluate SO2: Formed when sulfur in fuels/coke oxidizes.4) Compare options: Sets containing H2S or NO as primary are less characteristic for bulk emissions from steelworks; SO3 and NO2 are secondary or smaller fractions relative to SO2 and overall NOx.

Verification / Alternative check:
Emission inventories for steel plants consistently highlight CO, CO2, SO2 (along with NOx and particulates) as principal pollutants requiring control (e.g., desulfurization, optimized combustion, scrubbers, ESP/baghouse for dust).

Why Other Options Are Wrong:
H2S, NO, SO3: H2S emissions are more typical of sour gas processing; SO3 is a minor fraction formed downstream.CO2, H2S, NO2: H2S/NO2 are not the dominant trio for steel emissions.SO3, NO2, CO2: SO3 and NO2 are less predominant than SO2 and mixed NOx.

Common Pitfalls:
Confusing primary pollutants with secondary ones formed in the atmosphere.Overlooking CO as both pollutant and energy resource in steel plants.

Final Answer:
CO, CO2 and SO2