Sulfuric acid magnesium salt (1:1) → Sulfur Dioxide

An important advantageous feature of the process of the present invention is the fact that the magnesium values in the water treatment liquors can be readily recovered as magnesium oxide and recycled to the process. This was demonstrated in Example 1 as follows. The spent sulfite liquor ("red water") separated from the purified TNT was combined with the acid wash layer and the resulting mixture (pH 8.3) was neutralized to pH 7.2 with sulfuric acid and evaporated to dryness, yielding 5.9 grams of solids. A 2.0 gram aliquot portion of the solids was heated to redness (about 600° C) in a crucible, yielding 0.4 gram of gray ash, which was found by analysis to consist of approximately 55% MgO and 45% MgSO4. Complete conversion to MgO was accomplished by heating the ash to a still higher temperature in known manner. The MgO thus obtained, alone or as a mixture with the MgSO4, can be recycled by mixing it with fresh MgO or Mg(OH)2, as required, water and sufficient sulfur dioxide to form the magnesium sulfite-bisulfite solution for use in purifying crude TNT according to the process of the present invention. Volatile substances formed during the ignition of the solids from the spent sulfite liquor and consisting essentially of SO3, SO2, CO2, nitrogen oxides and water, were recovered by absorption in water.

ORD record

ord-3368d2addb534922b6aa713d64a85c7e

Source dataset

uspto-grants-1977_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04003953