Gas-scrubbing and metal-refining process and system

In a metal-refining system, the combination comprising:

• a container for reacting a metal compound with an acid in a liquid and solid mixture contained in said container with production of solid particles and toxic vapor products, a first air intake tube opening within said liquid and solid mixture and an exhaust line serially including said first air intake tube and said container with said first air intake tube defining the upstream end of said line, the downstream end of said line being connected to a source of vacuum, a gas flow-adjustable second air intake connected to said line adjacent said downstream end to adjust the vacuum in said line, said line serially including, downstream from said container, a sump and a heat exchanger disposed above said sump, said sump collecting solid particles entrained by the vapors flowing through said line from said container to said sump, said sump also collecting liquid condensate formed in said heat exchanger, said line further serially including downstream from said heat exchanger a vapor purifying means including an upstream and a downstream tank each containing a liquid and each having a vapor outlet at the top of the tank, the liquid in said upstream tank being water, the liquid in said downstream tank being a water solution of a substance selected from the group consisting of caustic soda and slaked lime, a casing in each tank immersed in said liquid, the casing in said upstream tank having a vapor inlet serially communicating through said line with the downstream end of said heat exchanger, the casing in said downstream tank having a vapor inlet connected to the vapor outlet of said upstream tank, each casing having a wall formed with a plurality of tiny gas outlet apertures for producing gas bubbles rising in said liquid, each casing enclosing entrance tubes, each having an outlet end fixed to the inside of said wall and communicating with one of said gas outlet apertures, each entrance tube having an inlet end opening within said casing, whereby any solid particles in said casing reaching said inlet end of said tube will fall back towards the bottom of said casing, thereby preventing clogging of said gas outlet apertures.