Client: Botash – Botswana Ash (Pty) Ltd.
Industry: Sodium Minerals Beneficiation / Salt Mining
Region: Makgadikgadi Region, Botswana
Product: 4 X AGF42D – Autonomous Gravity Sand Filters, ±20 MLD
Installation: 1990

Challenge

• Botash is the region’s largest producer of natural sodium products and currently produces variants of soda ash and salt.
• Botash, distributes its products to most SADC countries.
• At the Botash operations, water is pumped from boreholes out of the salt pans into solar ponds where, through evaporation, it is concentrated into brine.
• A critical filtration process is required before the brine solution is pumped into the processing plant, where soda ash and salt are extracted.

Application

• AGFs are used to clear the brine extracted from the Sua Pan of suspended solids.

Solution

• The design consultant from UHDE Consulting relied on the technical expertise of the Superior Filtration team to find the right solution.
• Four identical Superior Filtration AGF42D autonomous mechanical rapid gravity sand filters with a 20 MLD capacity in total, were installed in 1990.
• These filters were customised for Botash with rubber-lined backwash storage compartments, stainless-steel parts, and
  piping.
• Factors taken into consideration:
  • High Efficiency
    • Completely autonomous filtration and backwash
    • Thorough filter bed cleaning 

• • High Reliability
    • No moving or rotating components
    • No peripherals (backwash pumps, controllers, compressors)

• • Low Maintenance
    • Staffing is limited to periodic oversight
    • Maintenance is limited to mechanical structure integrity
    • Only periodic replacement of nozzles and sand

• • Lowest Lifetime Cost
    • Exceptional durability in the harshest conditions
    • Works for decades with minimal maintenance or input

Results

• A fit-for-purpose, customised filtration solution.
• After 34 years of continuous autonomous operation in an industrial chemical process and under harsh salt mine conditions, the AGFs offer excellent filtration with extreme reliability and durability.
• Since the installation of the AGF filters at the Botash plant in 1990, the filters have only required periodic replacement of underdrain nozzles and filter sand.
• The AGF filters operate autonomously without electricity, human intervention or downtime.