Metal in situ immobilization within density variant bodies of water

Abstract

A method for treating (in situ) large bodies of water con ta minated with heavy metals and having varying density stratas to immobilize the contaminant metals is disclosed. The method, or process for (in situ) immobilization of metals is focused on treating large bodies of water having metals therein that are also adjacent a border of soil or earthen materials in an attempt to immobilize the metals from penetrating through the soil. The method is also able to treat the soil water boundary within the pit lake to provide additional immobilization. The pit lakes can include open pit lakes, subterranean mine lakes, flowing streams and the like. The method is also able to treat an abandoned mine prior to the filling of the mine with water. Initially, the density mean of the body of water is determined, which is densest typical at regions at or approaching 4 degrees C. The process includes introducing a treatment substance that has a density greater than that of the density means into the body of water, providing at least one microbe proximate or in the body of water, producing microbial sulfides arising from the initial microbe placement, causing microbial sulfides to react (in situ) with metal ions or m etal containing compounds located within the body of water, reducing the solubility of the metal ions by forming metal sulfides, and inhibiting the migration rate of the metal ions or other metal containing compounds within or from the soils or earthen materials as they settle out of the water.

Description

Background technique [0001] The present invention relates to methods for in situ immobilization of metals in water and at soil-water boundaries, as well as for immobilization of metals in water having areas of different densities and for the treatment of all areas of water and water-soil boundaries. [0002] Waste is produced by many types of industrial processes, often resulting from the extraction of valuable materials. Waste piles are often built up of cheap materials left over from industrial processes. For example, power plants often produce large amounts of ash. These ashes are left behind when fuel is burned for energy. Mining processes also often leave behind waste, which is mineral-containing waste that is left behind when valuable metals and minerals are extracted from the ore material. Phosphate rocks, for example, often leave behind gypsum-based waste during processing. When phosphorus is extracted from the ore material, the waste gypsum that is left behind is ...

AI Technical Summary

Problems solved by technology

First, both treatments are expensive to implement because the cost of pumping water alone is extremely high

Second, mixing treated water with sewage would only result in re-contamination of the clean water, or would require another storage unit, which is not readily available or would pollute the soil in the same way as the first pit lake

Third, treatment plant operators must be on the water during on-lake treatment, which may unnecessarily expose operators to sewage

Fourth, these treatments sometimes fail to reach the depths of these pit lakes, especially when the pit lakes are in the range of 50 feet to 3000 feet

Also, pumping water in pit lakes is expensive

Fifth, some water injection works are done entirely underground, where direct access is virtually impossible, or costly impractical because water is pumped from underground caverns to the surface for disposal

Existing techniques that move water from the surface of the pit lake to a separate location for treatment, or simply treat the water on the surface of the pit lake, do not treat the soil boundaries of the lake at the same time as the water treatment

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