Atmospheric particulate matter related to industrial processes
Origin, levels and physical-chemicals properties
Every day it seems clearer that the environmental factor must be included as part of the overall business management of companies. In this aspect, the metallurgic industry aims for a more sustainable and eco-efficient production. Added to this is a growing social awareness of environmental issues and an increasingly restrictive European environmental law, which focuses on implementing more environmentally-friendly systems and the health of the workforce.
One area in this field which garners special interest is the generation of pollutants and their emission into the atmosphere. According to the data from the State Register of Emissions and Sources, the metal manufacturing and transformation industry is a significant source of emissions of particulate matter and heavy metals.
Atmospheric particulate matter comprises small (< 100 μm) solid or liquid particles which are suspended in the atmosphere. The particles of less than 10 μm (PM10) are considered the most critical ones because they can easily be inhaled and potentially affect health. It is without a doubt one of the factors which must be taken into consideration at each stage of the process in the foundry industry, starting with the storage and transportation of raw materials and ending with the finishing of components.
Besides the control systems demanded by the Integrated Environmental Authorizations, IK4-AZTERLAN is carrying out advanced investigation and study projects in environmental pollution, with the aim of identifying the main emission sources and establish improvement measures that will minimise their impact.
The methodology to be used varies depending on the type of study performed (immission, emissions control and environmental control in the factory), but all of them begin with sampling campaigns, in order to later characterize the particulate matter.
Using advanced analysis techniques as a springboard for characterizing these samples, provides determining information regarding the type and proximity of the emission sources.
Scanning Electron Microscopy (SEM) is an important tool for characterizing the individual particles in high resolution, as well as obtaining the spectra composition of samples. The differences in the chemical composition of the particles make those which hold more atomic weight (heavy metals in general) be displayed clearer and brighter than the rest. In addition the size or form of the particles, morphology provides information regarding the age (in other words, proximity of the emission) and in some cases helps to identify the processes which generate them, as well as the synthesis temperature.
The identification of trace metals in the fine particle fraction is used to draw a map of the sources.
Below are some images of particulate matter captured from metal-mechanic transformation processes.
