Currently, most of the use of tailings backfill of gold ore, ferrous sulfate treatment using gold plant tailings. The ferrous ion in the solution reacts with the free cyanide to form ferrocyanide (Fe 2 + +6CN - →Fe(CN) 6 4- ). A disadvantage of this reaction process is that the ferrocyanide produced is unstable under high temperature, low pH and ultraviolet irradiation conditions, and this solution may also ooze out during the backfilling process, contaminating the natural groundwater.
When an excess of ferrous sulfate is added to the cyanide-containing solution, the cyanide can be changed to an insoluble precipitate Fe 4 [Fe(CN) 6 ] 3 , which is Prussian blue. Some add insoluble ferrous sulfide, and some white insoluble ferrous ferrocyanide formed by adding iron and copper , quickly absorb oxygen from the air, and turn into dark blue to form iron ferricyanide. However, there are many different conditions for Prussian blue vision. Therefore, this reaction is not so simple. One of these is called "soluble Prussian Blue", ie MFe III [Fe II (CN) 6 ] (M is K or Na), which forms a colloidal solution with water. In addition, precipitation and oxidation of ferrous hydroxide are also active reactions.
Thus with FeSO 4 solution was removed from the optimal conditions cyanide, it is to find the process of generating a soluble and insoluble compounds.
The experiment firstly reacted FeSO 4 with CN - to form a molar ratio of Prussian blue. The stoichiometric ratio of Fe to CN - was 0.39, but the experimental results showed that the optimum molar ratio was 0.5. The optimum pH for precipitating Prussian Blue is 5.5 to 6.5, while the pH for decomposing Prussian Blue is 10.5. The presence of oxygen oxidizes Fe 2 + to cyanoferrate and ferricyanide without facilitating the removal of cyanide. Because the ferrocyanide ion is unstable in an acidic solution, the ferrocyanide ferrous complex [Fe(CN) 5 H 2 O] 3 - is formed and rapidly oxidized to ferricyanide ion Fe(CN) 6 3- . These reactions occur at pH below 4.
The precipitation of the excess FeSO 4 and CN - is mainly composed of insoluble Prussian blue Fe 4 [Fe(CN) 6 ] 3 . At a pH of 1 to 7, the Prussian blue precipitate is stable; however, it is unstable in an alkaline solution and rapidly decomposes in solution to form Fe(CN) 6 4- . When the pH is higher than 7, Prussian blue also forms various insoluble ferrites Fe 2 O 3 ·nH 2 O (n = 1 to 3).
According to environmental protection regulations, cyanide in the solution should be reduced to a specific level, but does not involve cyanide in the solid. It is therefore necessary to optimize the FeSO 4 process in order to form a Prussian blue precipitate without the formation of soluble ferrocyanide. FeSO 4 with the addition of cyanide optimal conditions of pH 5.5 ~ 6.5, Fe and CN - ratio of 0.5.
Key Specifications/Special Features
Materials: aluminum, alloy steel, brass, cast iron and steel
Lost wax casting
Surface treatments: sand painting, electrophoresis and zinc plating
Heat treatments: tempered or annealed and induction hardened
Machining: CNC turning, milling, drilling and boring
Weight: 0.2 to 60kg
Packing: customized
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About the commodity:
1).25-year experiences
2).Certification:ISO9001:2000
3).Material:brass
4).Process:polishing,nickel plating,chrome plating,etc
5).Weight range:0.2-60kg
6).Min tolerance:0.05mm
7).Standard:Nonstandard JIS,DIN,ASTM,BS,SAE
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We supply all kinds of metal products,The line of our products include constraction parts, auto parts, railway parts, marine parts etc.
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Steel Forging Ring
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