**3.8. Measurements of the weight of trapped aerosol particles in selected locations of the steelworks convertor hall**

During the performed technological operations in the steelworks convertor section, the following measuring points were selected:


with impactors for collection of aerosol particles sorted in agreement with the specified sorting levels (Table 11). The table contains the subsequently weighed particles by fractions and conversions into volume concentrations in the proximity of the technology operation.


a) air flow rate 10l/min. for a period of 5 minutes.

448 Atmospheric Aerosols – Regional Characteristics – Chemistry and Physics

**Figure 32.** Distribution of aerosol particles in the measuring point b)

**concentration (N·cm-3)** 

**Table 10.** Measured physical values of nanoparticles – point b)

**locations of the steelworks convertor hall** 

following measuring points were selected:

furnace into the ladle,

in the previous case.

**Measuring point b) Overall** 

The maximum peak of the doublet shape in the area around 20 nm corresponds to the distribution measured in the measuring point a) but the concentration of the particles was higher. Another area with an increased number of particles is around 120 nm, while this phenomenon was not observed in the previous case. The overall concentration of particles in the nano area is by one order of magnitude higher, the weight of the particles 5x higher than

> **Total surface of the particles (nm2·cm-3)**

Average values 1.4 . 105 4.03 . 109 1.38 . 1011 166

During the performed technological operations in the steelworks convertor section, the

with impactors for collection of aerosol particles sorted in agreement with the specified sorting levels (Table 11). The table contains the subsequently weighed particles by fractions and conversions into volume concentrations in the proximity of the technology operation.


**3.8. Measurements of the weight of trapped aerosol particles in selected** 

**Total volume of the particles (nm3·cm-3)** 

**Total weight of the particles (µg·m-3)** 

**Table 11.** Individual trapped fractions of aerosols in the first impactor

Samples of trapped particles at the pourover of raw iron were submitted for electron microscope analysis. The images made by the electron microscope based on the particles trapped in the filter by sorting levels are shown in Figures 33 and 34.

Pictures made by a scanning electron microscope show visible particles from several hundreds of nanometers to ca. 5µm. The evaluation of the sizes of the observed particles has made it possible to estimate that the most numerous particles were in the range from 1 to 2µm. The prevailing majority of trapped particles in fine atmospheric aerosols were spherical; see Figure 33. In agreement with the generally accepted theory, particles of the size of units of micrometers are formed directly by the solidification of finely dispersed liquid aerosol of liquid iron. If the cooling rate is sufficient, round particles with some signs of crystalline structure of atoms on the surface appear instead of crystalline formations. On the contrary, if the conditions for a transition into a solid state are different, particularly in terms of the cooling rate, then fairly interesting crystalline formations can be found between the particles, as shown in Figure 34. The resulting product is actually an aggregate of very small crystals which came into immediate contact in the atmosphere.

The entire process of formation of the fine aerosol is accompanied by a chemical reaction in which melted iron particles are in a thermodynamic imbalance with oxygen from the atmosphere, and therefore an intense exothermic chemical reaction occurs on the surface of the particles which produces oxidation products of iron. The resulting formations are shown in the pictures. A chemical analysis of particles with EDS has confirmed the variable values of the Fe/O ratio. In some cases the atomic ratio Fe/O was > 3/2, which may be explained by the presence of non-reacted iron in the particle core.

Sorting level A Sorting level B

Experiences with Anthropogenic Aerosol Spread in the Environment 451

Sorting level A Sorting level A

environment of raw iron casting

pre-treated melt after desulfurization

**4. Discussion about the toxicity of iron particles** 

**Figure 34.** Images from electron microscope of trapped particles of non- typical shapes from the

**Figure 35.** Electron snapshots of trapped nano- and micro- particles from the site of the pourover of

Iron in suitable concentrations is an element essential for human health which participates in the transport of oxygen (hemoglobin, myoglobine) in cellular breathing. If the

Sorting level C Sorting level D

**Figure 33.** Images from electron microscope of nano- and microparticles from the environment of the pourover of raw iron from the railway carriage

Samples of particles trapped in the impactor were collected at the site where pre-treated melt of raw iron was poured over after desulfurization, and they were analyzed by electron microscope. In addition to the minor number of spherical particles (composed of iron, iron oxide and iron-calcium), the images also show carbon-based non-spherical and non-metallic particles. A characteristic illustration of particles trapped in the impactor is shown in Figure 35. The content of the trapped particles was probably influenced by the composition of the residual slag that remained in the melt after the tapping. The melt desulfurization, as mentioned at the beginning, is performed by the addition of calcium carbide, magnesium and lime, so the presence of calcium is completely logical.

Experiences with Anthropogenic Aerosol Spread in the Environment 451

Sorting level A Sorting level A

450 Atmospheric Aerosols – Regional Characteristics – Chemistry and Physics

Sorting level A Sorting level B

Sorting level C Sorting level D

pourover of raw iron from the railway carriage

and lime, so the presence of calcium is completely logical.

**Figure 33.** Images from electron microscope of nano- and microparticles from the environment of the

Samples of particles trapped in the impactor were collected at the site where pre-treated melt of raw iron was poured over after desulfurization, and they were analyzed by electron microscope. In addition to the minor number of spherical particles (composed of iron, iron oxide and iron-calcium), the images also show carbon-based non-spherical and non-metallic particles. A characteristic illustration of particles trapped in the impactor is shown in Figure 35. The content of the trapped particles was probably influenced by the composition of the residual slag that remained in the melt after the tapping. The melt desulfurization, as mentioned at the beginning, is performed by the addition of calcium carbide, magnesium

**Figure 34.** Images from electron microscope of trapped particles of non- typical shapes from the environment of raw iron casting

**Figure 35.** Electron snapshots of trapped nano- and micro- particles from the site of the pourover of pre-treated melt after desulfurization
