Kraft mill recovery system

DETAILED DESCRIPTION What is claimed is: 1.
In the process for the pulping of lignocellulosic material wherein a.
lignocellulosic materials are cooked with pulping liquor; b.
the pulping liquor is evaporated and combusted; c.
inorganic and organic solids mixed with the combustion gases are precipitated as precipitator catch containing sodium sulfate, sodium chloride, sodium carbonate and organic material; d.
said sodium carbonate is converted to sodium sulfate with aqueous sulfuric acid at a pH of from about 3 to about 6 to produce a treated precipitator catch slurry containing sodium sulfate, sodium chloride and organic material; the improvement which comprises passing said treated precipitator catch slurry into the top of a separatory column, in a downward flow; countercurrently passing hot water upwardly through said column at a rate sufficient to effect washing of the downwardly flowing slurry; removing said sodium chloride from the top of said separatory column; and removing said sodium sulfate and organic material from the bottom of said separatory column.
2.
The process as defined by claim 1 wherein the process is a continuous process.
3.
The process as defined by claim 1 wherein the temperature of the hot water is maintained at from about 30.
degree.
to about 70.
degree.
C.
4.
The process as defined in claim 1 wherein the hot water is fed into the separatory column at a rate sufficient to provide from about 0.
2 to about 4 pounds of water per each pound of sodium sulfate.
5.
The process of claim 4 wherein said rate provides from about 0.
2 to about 2.
0 pounds of water per pound of sodium sulfate.
6.
The process of claim 1 wherein said separatory column contains multiple plates incorporating therein multiple downwardly tapering funnel-shaped configurations for discharging slurry downward into turbulent zones and multiple apertures near the junction of the column wall allowing upward flow of water.




Description:
The present invention relates to kraft pulping processes.
More particularly, the present invention relates to reduction of losses in kraft pulping processes