Liquid storage apparatus and method of controlling the pressure in the same

A liquid storage apparatus for use as a sulfurization facility for sulfurizing a sulfate solution to produce a sulfide in the sulfurizing step of a wet smelting for nickel oxide ore, the apparatus comprising:

• a plurality of liquid storage vessels, wherein each vessel including a feed conduit for feeding a slurry after the sulfurizing after a sulfurizing reaction and a filtrate after a solid/liquid separation, a gas charge/discharge conduit for charging an inactive gas and discharging a gaseous component at gaseous phase as an exhaust gas, and a discharge conduit for discharging the slurry or the filtrate;
• a collective conduit arranged of a branched shape having a series of joints at one end of the collective conduit aligned in parallel with the gas charge/discharge conduits of respective said liquid storage vessels and connected via the joints to the gas charge/discharge conduits for collectively passing the inactive gas to be fed to the liquid storage vessels and the exhaust gas discharged from the liquid storage vessels;
• and
• a pressure control conduit for receiving at one end the inactive gas to be fed to the liquid storage vessels and releasing at an other end the exhaust gas discharged from the liquid storage vessels, wherein the pressure control conduit is connected by a junction to the one end of the collective conduit and is equipped with a pair of pressure control valves mounted on the collective conduit at both, front and rear, sides of the junction so that both the feed of the inactive gas to the liquid storage vessels and the discharge of the exhaust gas from the liquid storage vessels can be controlled by the pressure control valves.