Environmental pollution and treatment of acidic water in pyrite mines

Pyrite quickly to produce acidic water with water, such as iron ore mine sulfur yunfu perennial observation, waste rock and pH of the large reservoir units on average is about 3.5. Yunfu Pyrite Mine has adopted measures to strictly control acidic water, actively control acidic water, strengthen management in the whole process of production, and strengthen comprehensive management.
Prevention of pollution sources is a cost-effective measure to intercept incoming water from stope and waste rock to reduce the amount of acid water produced; to seal the surface of the ore, to isolate contact with air and moisture; to properly ore dressing to reduce acidic water The production.
Despite some comprehensive treatment methods, the production of acidic water is still inevitable. The treatment of simple acidic water in the Yunfu pyrite mine is to use a reverse-cone type swirling pool limestone powder to neutralize the acidic water process. The water quality can be raised from 3.0 to 6.5, and then clarified by a multi-stage advection sedimentation tank. The water quality can fully meet the national industrial wastewater discharge standard.
For complex acidic water (acidic water with particularly high content of manganese , zinc and iron), a two-stage neutralization process is adopted, that is, the first stage is neutralized with limestone powder in an inverted cone swirling tank, and the pH is raised from 3.0 to 4.5, the first The second-stage fertilization lime is neutralized by a drum or a stirred tank, and is discharged after being clarified by the advection sedimentation type. In 1992, Yunfu built a large-scale acid water treatment station.
The acid water of the general mine is treated with lime milk neutralization and discharge. At present, most of the pyrite ore beneficiation adopts alkaline process flotation, which can avoid acid corrosion of equipment, and the ore dressing wastewater is alkaline water and underground acidity. Discharged in the water after the standard. Some beneficiation processes require the addition of sulfuric acid. The use of underground acidic water can save some of the sulfuric acid, reduce the cost of ore dressing, and make rational use of some acidic water. It is also a more reasonable method, but the process index of ore dressing should be guaranteed.

"Gravity Die Casting. A permanent mould casting process, where the molten metal is poured from a vessle of ladle into the mould, and cavity fills with no force other than gravity, in a similar manner to the production of sand castings, although filling cn be controlled by tilting the die."

Gravity Die Casting

Sometimes referred to as Permanent Mould, GDC is a repeatable casting process used for non-ferrous alloy parts, typically aluminium, Zinc and Copper Base alloys.

The process differs from HPDC in that Gravity- rather than high pressure- is used to fill the mould with the liquid alloy.

GDC is suited to medium to high volumes products and typically parts are of a heavier sections than HPDC, but thinner sections than sand casting.

There are three key stages in the process.

  1. The heated mould [Die or Tool] is coated with a die release agent. The release agent spray also has a secondary function in that it aids cooling of the mould face after the previous part has been removed from the die.
  2. Molten metal is poured into channels in the tool to allow the material to fill all the extremities of the mould cavity. The metal is either hand poured using steel ladles or dosed using mechanical methods. Typically, there is a mould [down sprue" that allows the alloy to enter the mould cavity from the lower part of the die, reducing the formation of turbulence and subsequent porosity and inclusions in the finished part.
  3. Once the part has cooled sufficiently, the die is opened, either manually or utilising mechanical methods.

Advantages

  • Good dimensional accuracy
  • Smoother cast surface finish than sand casting
  • Improved mechanical properties compared to sand casting
  • Thinner walls can be cast compared to sand casting
  • Reverse draft internal pockets and forms can be cast in using preformed sand core inserts
  • Steel pins and inserts can be cast in to the part
  • Faster production times compared to other processes.
  • Once the tolling is proven, the product quality is very repeatable.
  • Outsourced Tooling setup costs can be lower than sand casting.

Gravity Casting Parts

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