PROJECT DESCRIPTION
BACKGROUND
Quartz is one of the most widely used raw materials in European industry, irreplaceable in many applications due to its unique properties and low price. Total European usage of crystalline silica (i.e. quartz and cristobalite) is measured in thousands of millions of tonnes per annum. It is used in many manufacturing industries such as the cement, ceramics, foundry, glass, mineral wool, aggregates, mortar and concrete sectors. However, prolongedinhalation of respirable crystalline silica particles can cause lung inflammation and the lung disease known as silicosis. Hence, a vast number of European workers, around four million (European Trade Union Confederation, 2007), are potentially exposed to Respirable Crystalline Silica (RCS). Although it is not possible to substitute crystalline silica in many sectors, it is possible to nullify its toxicity by treating it with certain substances.
OBJECTIVES
Quartz is one of the most widely used raw materials in European industry, irreplaceable in many applications due to its unique properties and low price. Total European usage of crystalline silica (i.e. quartz and cristobalite) is measured in thousands of millions of tonnes per annum. It is used in many manufacturing industries such as the cement, ceramics, foundry, glass, mineral wool, aggregates, mortar and concrete sectors. However, prolongedinhalation of respirable crystalline silica particles can cause lung inflammation and the lung disease known as silicosis. Hence, a vast number of European workers, around four million (European Trade Union Confederation, 2007), are potentially exposed to Respirable Crystalline Silica (RCS). Although it is not possible to substitute crystalline silica in many sectors, it is possible to nullify its toxicity by treating it with certain substances.
RESULTS
The SILIFE project designed and developed a pilot quartz treatment for reducing the risks associated with Respirable Crystalline Silica (RCS) in the workplace. This represents a major step towards producing commercial quartz powders that show very little or no RCS toxicity, which can be used in many industrial processes.
Firstly, relevant data on the processes (exposure hot spots, production, etc.) and raw materials (particle size distribution, surface area, etc.) were collected. Then, a selection of the best candidate silanes (silicon hydrides) for surface-treating dry quartz powder was made. The conditions for the silane application, by a dry method (using as reactor equipped with a high shear-rate powder mixing system, a heat exchanger and a specifically designed dosage system), were established. The results were found to be similar to those from the wet application method (aqueous suspension) developed in a previous FP7 project, SILICOAT.
The pilot prototype was designed and the project partner BCL (Bulk Cargo Logistics) responsible for the production of the coated quartz adapted the equipment to their requirements. Sufficient quantities of the different quartzes provided by the end-user partners were treated with the developed technology, and then, sent back to the respective facilities for testing.
After the assessment of the suitability of the treated quartzes for the respective processes and final products, the end users performed industrial trials using treated and non-treated quartz, comparing behaviour and products. In some cases, changes in the equipment conditions or in the silanes used were required to get successful results. At the end, all results were successful, except for some foundry situations that will need deeper study in a post-project action. Toxicological assessments of quartz were performed during thedifferent stages of the project. These consisted of in vitro and in vivo screening to: a) estimate the adverse biological activity of different quartzes selected for coating trials; b) screen coating efficiency of samples from laboratory-scale trials to select coatings for industrial trials; and c) test adverse biological activity of bulk and respirable (dust) samples from industrial coating trials to validate the toxicity reduction.
By the end of the project, the silane coating was proven to reduce the toxicity of RCS, but from the legal point of view the coated RCS remains catalogued as RCS. In this framework, the SILIFE process can be a complementary measure, but not an overall solution. SILIFEs key innovation was to adapt the coating technology developed in the SILICOAT project to obtain dry powders. Therefore, SILIFE has introduced, at industrial scale, a technology that had never been applied before. The project also comprised several significant demonstration activities regarding the feasibility of use of the treated quartz powders by end-users. In particular, a series of quartz (and cristobalite) end-users were gathered into the project, belonging to the following sectors: foundries, frits (special glasses) and ceramic glazes, plastics, adhesives, and specialty inorganic chemicals.
Among the socio-economic benefits are healthier workplaces, and a more sustainable use of crystalline silica - one of the most thoroughly used industrial chemicals. Though targeting a health-related problem, there is an important business opportunity in the production of non-toxic quartzes for a global market. To this end, a European patent (EP19382177.4) was applied for in March 2019 for the industrial process for producing quartz and other quartz-containing raw materials with reduced toxicity relating to respirable crystalline silica (RCS).
Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).
