Investigative analysis of the key physical and chemical properties of processed recovered carbon black to establish a quality benchmark and consistency

The demand for recovered carbon black (rCB) is growing rapidly; the main reason for this growth is the rising demand for sustainable alternatives to carbon black. This growth aligns with the United Nations' sustainable development goals (SDGs) 9, 11, 12, and 13 because it promotes the recycling of waste tires through pyrolysis into products, hence reducing the reliance on fossil fuels used to make carbon black. It also supports the development of sustainable products, thus reducing emissions and supporting the development of circular economy products. This expansion, however, will incur critical challenges associated with the large production, handling, and transportation requirements.

A new rCB beneficiation plant in South Africa aims to enter into the rCB manufacturing market, but to do this, it needs to not only optimize its process but also the products for ease of handling and transportation. However, the inherent variability and presence of contaminants in and low bulk density of rCB contribute to inconsistent material properties and significant dust generation during handling. Therefore, this new plant aims to standardize its rCB product through the development of proprietary treatment methods and further aims to reduce the dust by densifying the rCB through pelletization.

The objective of this study is to investigate the influence of these treatments and pelletization parameters on rCB quality. Raw and treated rCB samples were collected from the plant, and pellets were produced under varying binder conditions. Analytical characterization included bulk density measurements, proximate analysis (ash, volatile, and moisture content), ash composition (XRF), laser particle size analysis, and gas adsorption analysis (BET).

These tests aimed to assess how treatment and densification influence surface area, particle distribution, compositional stability, and pellet quality. Preliminary findings show a lower volatile content at a treatment temperature above 250 °C, with an average of 20% volatile matter removal when compared to the raw material.