Floated type shell&tube heat exchanger is mostly used for large temperature fluctuations and temperature differences, compared with Fixed Tube Heat Exchanger, its structure is more complex and more expensive.
One end of the tube is fixed on an immobile Tube Sheet, which is clamped between the shell Flange and the tube flange, and is connected by bolts; the other end of the tube is fixed on a floating head tube sheet, which is clamped between the floating cover and the hook ring connected by studs, forming a floating head that can move freely in the shell.
If the tube bundle and the shell are heated and elongated, they do not affect each other, so there is no temperature difference stress. The floating part is a detachable connection consisting of the floating tube sheet, hook ring and floating cover. It is easier to take the tube bundle out, and the tube can be cleaned both inside and outside and is easy access.
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Copper and nickel ore flotation is commonly used as a collector for xanthate, pine oil as a foaming agent, and copper sulfate as an activator. Nickel minerals generally require flotation in acid to weakly alkaline media. The optimum pH of pentlandite flotation is 4, and when the amount of yellow medicinal is higher, the pH range of flotation is wider, pH< 9.5 can float. Nickel sulfide minerals are inhibited in alkaline media formed by lime or in the presence of cyanide.
In an acidic medium (pH 5.0-5.5), Fe 2 + and Fe 3 + ions have a certain activation effect on the flotation of pentlandite. However, in alkaline media (pH 9～10), Fe 2 + and Fe 3 + ions have a strong inhibitory effect on the flotation of pentlandite, because FeO(OH) hydrophilicity is formed on the surface of pentlandite. Membrane, as the concentration of iron ions increases, the inhibition increases, so that pentlandite is completely inhibited.
Nickel-containing pyrrhotite is more difficult to float than other nickel minerals, and is activated by copper sulfate or treated with sulfur dioxide in an acidic medium.
The floatability of nickel sulfide minerals
Nickel-containing minerals dozens, wherein industrially mainly pyrite nickel (Fe, Ni) 9 S 8 , containing Ni21% ~ 30%; sulfur nickel ore needle NiS, containing Ni64.7%; nickel red NiAs, containing 43% of Ni; containing nickel pyrrhotite, containing NiOX%. Nickel and copper are often symbiotic. China's larger nickel ore is associated with copper, which is actually copper-nickel ore. Copper-nickel ore copper minerals, chalcopyrite is generally, often contain copper, nickel, platinum, palladium and other precious metals, the recovery should be noted.