Recuperation of Garnet Sand Sludge after Waterjet Cutting

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Waterjet cutting is an industrial technique used to cut a wide variety of materials ranging from metals, concrete, wood, rubber, foams, and plastic. The underlying principle is that water is engineered to flow  as a powerful high-pressure jet, usually at 50,000 to 90,000 PSI, through a specialized nozzle used to  cut these materials. However, harder substances such as metals, concrete, glass, and stone require an  additional force in conjunction with water for precise cutting. Appropriate ratios are achieved by mixing  water with an abrasive agent such as red garnet sand. The almandine species of red garnet is a common  type of abrasive used industrially and is mainly sourced from Australia, India, and China. Due to its optimal granular size, specific gravity, hardness, and density, it is most effective as an abrasive when coupled with a waterjet to maximize its efficiency. The combination of water and abrasive material in a  single stream is called an Abrasive Water Jet (AWJ). 

AWJ is known to have negative environmental impacts arising from the formation of wastewater, garnet  sludge and microscopic components of the cut material. The ratio of garnet sand to water for a specific  jet pressure generally accounts for about 70% of the total operational costs. Besides, the management  of these waste products proves to be an added cost as it requires additional procedures. Our project  aims to counteract these costs by recharging and utilizing up to 100% of the post-AWJ garnet sand  sludge produced. The goal is to obtain high-quality, fully reusable abrasive products with minimal impurities like dust and moisture. Additionally, our project aims to altogether avoid the unnecessary  disposal of this waste in household landfills, as it can be fully repurposed. 

AWJ technology applications are widespread across multiple industries globally like shipping. The United  States alone accounts for more than 5,000 units of AWJ installations, whereas the rest of the world  accounts for the installation of more than 7,500 units. The trend in this industrial application continues  to grow as the number of installations increase by about 30% each year. Therefore, there is a constant  opportunity for growth in the current market for recycling and reusing garnet sand, stemming from the tightening of environmental and sanitary standards. 

We have developed a highly efficient, original technology for recuperating post-AWJ garnet sand sludge,  in which experimental batches of secondary garnet sand products have been obtained, and quality  control has been carried out in industrial settings. Our tests have yielded positive results since 50-100  kg of secondary garnet sand was produced with a favourable granular size (100-315 microns).  Additionally, commissioning works are in progress for a project that has been developed for obtaining  secondary garnet sand from post-AWJ sludge at the rate of 1000 kg/hour. 

The global market for garnet is valued at 439.5 million USD in 2020 and is expected to reach 663.9 million  USD by the end of 2026. Our highly efficient method for repurposing garnet sand has multiple market  growth opportunities in the ship building, abrasive paper, water filtration, construction, and denim  fabric industries. Positive environmental impacts include the elimination of the need for landfill disposal. 

Ultimately, the core of our project is based on the framework that ensures thermal and electric energy saving during the AWJ process, the recuperation of garnet sand from post-AWJ sludge and the production of a wide range of garnet sand sludge products after the AWJ process.