Additive effects of Coal dust
and Iron ore dust (Iron Oxide)
A CASE OF AN IRON PROCESSING PLANT ZISCO STEEL IN
REDCLIFF KWEKWE
INNOCENT NJANJI
FUNGAI MAWESERE
KUDZAI HLAVATI
TERRANCE DURI
OVERVIEW OF AN IRON PROCESSING PLANT

We manufacture a wide range of hot rolled long steel sections for both local
and export markets namely Angle Irons, Flat Bars, Channel Irons, Window
Sections, Fencing Standards, Foundry Products, Sponge Iron (DRI), Industrial
Oxygen and we also process coal into various products

Iron ores consist of oxygen and iron atoms bonded together into molecules.

To convert it to metallic iron it must be smelted or sent through a direct
reduction process to remove the oxygen.

Oxygen-iron bonds are strong, and to remove the iron from the oxygen, a
stronger elemental bond must be presented to attach to the oxygen.

Carbon is used because the strength of a carbon-oxygen bond is greater than
that of the iron-oxygen bond, at high temperatures. Thus, the iron ore must be
powdered and mixed with coke, to be burnt in the smelting process.

The furnaces are mostly fueled by coal.
FOCUS AIRBORNE CONTAMINANTS

Iron ores are rocks and minerals from which metallic iron can be extracted.

There are four main types of iron ore deposit: Hematite, which is the most
commonly mined, Magnetite, Titanomagnetite, and Pisolitic ironstone.

The research is focused on the Iron ore dust and Coal dust as they have
Additive effects
EXPOSURE LIMITS/STANDARDS

Iron Oxide is 10mg/m3 - OSHA Standard

Coad dust is 2 mg/m3 – NSSA standard
SITUATION

The workers who work at furnace, responsible coal handling are also
exposed to the Iron ore dust from the adjacent conveyor which
feeds the ore to the furnace.

Upon measuring the dust levels for the two dusts (Iron ore dust and
Coal dust), the results indicated that the Coal dust was 14.2 mg/m3.
Further, the concentration of Iron ore dust was 12.7 mg/m3

It was also discovered that both dusts have effects the mid-lower
respiratory tract, causing Pneumoconiosis.
CALCULATION AND DISCUSION

Formula: C1/L1 + C2/L2
14.3 mg/m3
=
2 mg/m3

+
12.7 mg/m3
10 mg/m3
= 8.42
The calculated additive effect using the airborne concentrations and the OSHA
Exposure Standards is 8.42 and is more than 1. This means that, exposure
standards for the mixture is exceeded and there is need for a robust plan and
program to keep the workers safe.
RECOMMENDATIONS

Coal wetting

Local and mechanical ventilation systems

Dust scrubbing systems

Conveyor covers

Use of appropriate equipment to load coal into the bunkers

PE/C
THANK YOU