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TREATMENT OF HIGH ALKALINITY MINING WATER

IP.com Disclosure Number: IPCOM000239511D
Publication Date: 2014-Nov-13
Document File: 3 page(s) / 42K

Publishing Venue

The IP.com Prior Art Database

Abstract

The present invention proposes a technique for treatment of a high alkalinity coal seam gas (CSG) water or other mine water having high alkalinity. The technique includes ion exchange columns followed by a degasifier that removes most of the sodium, carbonates and bicarbonates. The CSG water mainly contains sodium, carbonate, bicarbonate and chlorides. The technique described herein offers an easy and low cost treatment of the CSG waters. The technique produces sodium nitrate, which is an expensive commodity that may be sold to offset operating expense of treatment of the CSG waters.

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TREATMENT OF HIGH ALKALINITY MINING WATER

BACKGROUND

The present invention relates generally to treating high alkalinity mining water and more particularly to a technique of treatment of the high alkalinity mining water involving ion exchange columns and a degasifier.

Coal seam gas (CSG) refers to any naturally occurring gas trapped by water and ground pressure in underground coal seams. CSG is growing as an energy source. Exploration and production of the CSG expels large quantities of brine, referred to herein as CSG water. CSG water mainly contains sodium, carbonate, bicarbonate and clorides. Treatment of CSG water is a challenge for mining companies. Due to stringent regulations, CSG water needs to be properly treated by mining companies involved in CSG production before being discharged into the environment. Currently used treatment procedures involve high capital and operating expenditure.

A conventional technique for treatment of CSG water includes use of reverse. Permeate water is recycled and concentrate water is sent to series of evaporators to produce soda ash and sodium bicarbonate. Both soda ash and bicarbonate are low cost commodities.

Another conventional technique uses ion exchange to treat CSG water. The technique uses regenerants which include sulphuric acid and hydrochloric acid. Use of sulphuric acid and hydrochloric acid produces sodium sulphate and sodium chloride respectively. Both sulphuric acid and hydrochloric acid are expensive reagents and dangerous to handle.

It would be desirable to have an effective and economical technique for treatment of the high alkalinity mining waters.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 depicts a technique for treatment of high alkalinity coal seam gas (CSG) water involving ion exchange columns and a degasifier.

DETAILED DESCRIPTION

The present invention proposes a technique for treatment of coal seam gas (CSG) water or other mine water having high alkalinity. As depicted in Figure 1, the technique includes ion exchange columns followed by a degasifier that removes most of sodium, carbonates and bicarbonates.

Figure 1-  Technique involving ion exchange and degasifier

CSG water mainly contains sodium, carbonate, bicarbonate and chlorides. CSG water is sent through a strong acid cation (SAC) ion exchanger. As depicted in below equation, the SAC ion exchanger has an ion exchange resin which removes sodium and replaces the sodium w...