Methods to Reduce Metals Content of Bleached Pulp While Reducing Bleaching Cost in a Chemical Pulping Process

Abstract

In accordance with certain embodiments of the present disclosure, a method of decreasing the amount of oxidizer required by a pulping or papermaking process is provided. The method comprises adding to a process stream or solution of the pulping or papermaking process an effective amount of urea hydrochloride to reduce the amount of oxidizer required by the pulping or papermaking process.

1 . A method of decreasing the amount of oxidizer required by a pulping or papermaking process comprising adding to a process stream or solution of the pulping or papermaking process an effective amount of urea hydrochloride to reduce the amount of oxidizer required by the pulping or papermaking process. 
     
     
         2 . A method as in  claim 1 , wherein the oxidizer comprises chlorine dioxide, ozone, oxygen, hydrogen peroxide, or combinations thereof. 
     
     
         3 . A method as in  claim 1 , wherein the oxidizer comprises chlorine dioxide. 
     
     
         4 . A method as in  claim 1 , wherein the oxidizer comprises hydrogen peroxide. 
     
     
         5 . A method as in  claim 1 , wherein an effective amount of urea hydrochloride comprises about 15 to about 60 lbs. per ton of oxidizer. 
     
     
         6 . A method as in  claim 3 , wherein an effective amount of urea hydrochloride comprises about 35 to about 60 lbs. per ton chlorine dioxide. 
     
     
         7 . A method as in  claim 4 , wherein an effective amount of urea hydrochloride comprises about 15 to about 20 lbs. per ton of hydrogen peroxide. 
     
     
         8 . A method as in  claim 1 , wherein the oxidizer required by the pulping or papermaking process is reduced by at least about 10%. 
     
     
         9 . A method as in  claim 1 , wherein the oxidizer required by the pulping or papermaking process is reduced by at least about 15%. 
     
     
         10 . A method as in  claim 1 , wherein the oxidizer required by the pulping or papermaking process is reduced by at least about 20%. 
     
     
         11 . A method of reducing one or more metals, impurities, or combinations thereof from a pulping or papermaking process, comprising adding to a process stream or solution containing pulp, metals, impurities, or combinations thereof of the pulping or papermaking process an effective amount of urea hydrochloride to reduce metals, impurities, or combinations thereof from the pulping or papermaking process. 
     
     
         12 . A method as in  claim 11 , wherein the one or more metals comprise aluminum, calcium, barium, magnesium, potassium, sodium, zinc, manganese, copper, iron, or combinations thereof. 
     
     
         13 . A method as in  claim 11 , wherein the one or more impurities comprise sodium sulfate, silica, lime, oxide, alumina, potash, sodium chloride, or combinations thereof. 
     
     
         14 . A method as in  claim 11 , wherein the one or more metals comprise transition metals. 
     
     
         15 . A method as in  claim 11 , wherein the one or more metals comprise calcium. 
     
     
         16 . A method as in  claim 15 , wherein the calcium content is reduced by about 50 to about 60%. 
     
     
         17 . A method as in  claim 11 , wherein an effective amount of urea hydrochloride comprises about 1 to about 4 lbs. of urea hydrochloride per ton of pulp. 
     
     
         18 . A method as in  claim 11 , wherein an effective amount of urea hydrochloride comprises about 1 to about 2 lbs. of urea hydrochloride per ton of pulp. 
     
     
         19 . A method of reducing oxidation of transition metals in a pulping or papermaking process comprising adding to a process stream or solution of the pulping or papermaking process an effective amount of urea hydrochloride to reduce oxidation of transition metals from the pulping or papermaking process. 
     
     
         20 . A method as in  claim 19 , wherein the transition metals comprise iron and manganese.