29 October 2024

29 October 2024

Silica sand, a cornerstone in the metal casting industry, plays a critical role in producing precision castings. CFlo's advanced foundry sand technology ensures superior performance, sustainability, and economic viability.

• Deposits: Silica sand is scattered across the globe and presence of significant deposits can be found in India, Indonesia, Vietnam, Australia, Brazil, USA and parts of Europe. These deposits of Silica sand are normally found in riverbeds, beaches, and deserts.
• Industrial Uses: Silica sand is crucial ingredient for many industries such as construction where it's used in concrete and mortar. The dependency of Glass industry in high purity silica sand is extremely high which increase with the requirement for float glass and solar glass applications. There are many other additional applications such as electronic industry, casting, paints pharmaceutical etc
• Environmental Considerations: CFlo is committed to addressing environmental concerns by adopting cutting-edge Zero Liquid Discharge (ZLD) processing technology, ensuring minimal impact on local ecosystems while maximizing resource efficiency.

Overall, silica sand is a versatile and widely utilized resource with both economic benefits and environmental considerations. However we have to be aware of the environmental challenges on mining of Silica Sand and thus we need to be looking at sustainable methods of processing silica sand for various applications.

High-Purity Silica: Elevating Casting and Glass Production Silica Sand for Casting and Glass application is required in the same size fraction mostly just that some of the chemical properties of Glass manufacturing are more stringent in nature and thus requiring additional processes to be able to achieve the required grades. In this article, we explore the characteristics of producing foundry sand in greater detail.

Foundry Sand

Foundry sand is a type of industrial sand specifically used in metal casting processes. It is characterized by its high purity, uniform grain size, and consistent shape, which are essential for producing high-quality castings. It typically has a high silica content, well-rounded grains, and a uniform size distribution, which contribute to its effectiveness in mold and core making. Its refractory nature (ability to withstand high temperatures) helps it to hold its shape and withstand the molten metal's heat during the casting process. The quality of foundry sand is define by its AGS (Average Grain Size) and AFS (Average Fineness Number). A typical table representing this is shown in Table 1.

AFS numbers are frequently used to denote the relative grading or grade of sand supplied The AGS gives a more accurate indication of grain size, in micrometres, and will indicate slight differences in sands having the same AFS number

Redefining Automotive Casting with Advanced Sand Technologies Automotive casting is a manufacturing process used to create automotive components by pouring molten metal into a mould, where it solidifies into a specific shape. The sand must be clean, uniformly sized, and of high quality to ensure the integrity of the castings. In the foundry industry, green sand casting is the most common method.

Green sand comprises high-quality silica sand, bentonite clay, water, and coal, with each component playing a crucial role in the casting process. Another major challenge can be is shortage of water therefore an option with high percentages of water recycling possibilities in the system which our company has developed with our ZLD technology.

Design and Technology

Our state-of-the-art Micrograder BT100 delivers unmatched precision, recycling 95% of water, and offers a modular design for rapid deployment and operational flexibility—perfectly suited for automotive casting and more. The cutting-edge ZLD technology, ensuring no liquid waste is discharged from the plant. This is crucial for sustainable operations, particularly in water-scarce regions. The plant’s modular design allows for maximum process efficiency by providing two products, one being the Foundry Sand and the oversize as Construction Grade Sand, with careful attention to material transfer points to retain as much material and water within the circuit as possible, maximizing product yield and minimizing environmental impact.

General Process Flow for Foundry Sand processing (BFD)

Key Features of Micrograder BT100

• Capacity: 100 TPH, ensuring high throughput. Plant operating hours can be managed as per requirement for up to 16-20 hours per day.
• Utilities Requirement: Power 300kW, Water 24m3/hour
• Main Product: Production of Foundry-grade Sand, suitable for precision automobile casting. AFS grade can be adjusted using interchangeable parts
• Secondary Product: Coarse and Fine graded Construction Sand.
• Cost Benefit: For example, the cost of acquisition for the Raw material in Gujarat, India is Rs 250 per ton, after processing the primary Product is fetching a price of around Rs.1200 per ton and By products at Rs. 600 per ton, on ex-works basis.
• Sustainability: By recycling 95% of process water, the plant significantly reduces its freshwater footprint. ZLD technology ensures no liquid waste is discharged from the plant, protecting local water bodies and ecosystems.
• Footprint: On account of high cost of land and site development The modular design of CFlo plant minimized the footprint, thus reducing the need for extensive civil works, resulting in substantial savings for the customer. This innovation also allowed the whole plant to be housed inside a building.
• Rapid Deployment: Modular design of the equipment allowed quicker installation compared to traditional static plants. Faster operational start-up was achieved in less than 2-3 weeks of arrival of the equipment at site resulting in reduction of pre-operative costs

Process Description:

• Stage 1: Sand is received in a feed hopper fitted with a belt feeder for effectively feeding sand ore to the circuit. The hopper is equipped with grizzly bars to eliminate large oversized material that can damage the hopper. It has a VSD and a belt weigher system, allowing continuous monitoring and control of the feed to the system. The belt feeder transfers the sand to the feed conveyor, which delivers the ore sand to the processing circuit.
• In Stage 2: of the sand processing workflow, the material undergoes several key phases. Initially, raw material is fed onto a screen for the Initial Screening. Here, oversized material (+3mm) is separated and dewatered, ready for stockpiling as construction-grade sand, while the undersized material (-3mm) is collected in a sump and pumped into the next stage. Precision Sizing follows, where the sand slurry is pumped onto a sizing screen for separation at 600 microns. The oversize material is stockpiled after moisture reduction, while the undersize (-600 microns) proceeds to further processing. During further processing, a hydrocyclone removes ultrafine particles from the undersize, and the remaining slurry is discharged onto a dewatering screen, reducing the moisture content to prepare it for the final stages. The final processed sand is handled via a conveyor system that discharges the product onto a mobile stockpiling conveyor, creating multiple stockpiles of foundry-grade sand
• Stage 3: involves the Water Recycling System (WRS). The cyclone overflow, containing fines and clays, is gravity-fed to the WRS for settling. Dense sludge is managed by pumping it to a customer-provided system or settlement tank, while the wastewater is discharged to the sludge pond via an in-built slurry pump. To facilitate the process, polymer is mixed in a dosing tank, stirred by agitators, and fed into the sludge pond. The polymer action allows for quick adhesion, where water separates from the slurry and begins to solidify. Clear water from this process is pumped back into the system for reuse. Additionally, the thickener overflow recycles the majority of clean water back into the system immediately.
• Automation of the entire process is ensured by an advanced Programmable Logic Controller (PLC) system. Housed in an air-conditioned cabin, the PLC system enhances productivity and reduces human error by providing real-time monitoring and adjustments to operations, ensuring efficient and precise control

Keeping in line with a robust requirements of the customers, CFlo’s Micrograder BT100 model has been designed to give the best possible return on investment by converting the reject oversize into a valuable product for the customer in the form of Construction Sand. This however does not overlook the environmental impacts of high water requirements thus this plant recycles 95% of the water in the system making it a win-win situation for the buyer.