Nickel sulfate wastewater treatment process

General wastewater treatment process flow diagram at a typical nickel sulfate plant is shown in Figure 22.12. 

In 1996, costs for SLM technology treatment of a wastewater system typical of that found in the nickel-plating industry were compared to those for reverse osmosis treatment of the same amount of wastewater. It was assumed that wastewaters would be processed at a feed rate of 30/gal min, 15 hr/day, and 20 days/month. It was also assumed that a total of 175 lb of nickel sulfate, 45 lb of nickel chloride, and 225 lb of chromium salts would be removed. 

The raw minerals mined from natural deposits comprise mixtures of different specific minerals. An early step in mineral processing is to use crushing and grinding to free these various minerals from each other. In addition, these same processes may be used to reduce the mineral particle sizes to make them suitable for a subsequent separation process. Non-ferrous metals such as copper, lead, zinc, nickel, cobalt, molybdenum, mercury, and antimony are typically produced from mineral ores containing these metals as sulfides (and sometimes as oxides, carbonates, or sulfates) [91,619,620], The respective metal sulfides are usually separated from the raw ores by flotation. Flotation processes are also used to concentrate non-metallic minerals used in other industries, such as calcium fluoride, barium sulfate, sodium and potassium chlorides, sulfur, coal, phosphates, alumina, silicates, and clays [91,619,621], Other examples are listed in Table 10.2, including the recovery of ink in paper recycling (which is discussed in Section 12.5.2), the recovery of bitumen from oil sands (which is discussed further in Section 11.3.2), and the removal of particulates and bacteria in water and wastewater treatment (which is discussed further in Section 9.4). 

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