High density, high stability, sized metal oxide powder and process for making same

Abstract

The present invention relates generally to a novel approach to treating spent pickling acids, and a useful product resulting from such treatment or recycling approach. More specifically, the present invention is directed to compositions of matter of a high density, high stability, high absorption capacity composite metal oxide preferably comprising designed ratios of iron oxide and zinc oxide from inexpensive, waste raw materials such as, spent hydrochloric galvanizing pickling acids. Further, the present invention describes a process for reacting the spent pickling acids with an alkali hydroxide, oxide or carbonate to generate an alkali chloride and a mixture comprising iron and zinc oxides and hydroxides. The product of the reaction is then filtered, and the content of the alkali in the solids is adjusted according to application requirements, after which the solids are calcined and then screened to a required particle size. One beneficial application of the composite metal oxide of the present invention is its use as a drilling fluid weighting agent.

1 . A process of making a high density, high stability metal oxide mixture from waste spent pickling acid comprising the steps of: 
 a. providing a waste spent pickling acid having a desired ratio of metals;    b. reacting the pickling acid from step (a) to make a slurry consisting of solids comprising primarily metals and an aqueous liquid comprising primarily an alkali chloride;    c. filtering the slurry from step (b) to separate the aqueous alkali chloride from the solids thereby forming a liquid stream comprising alkali chloride filtrate and a filter cake comprising primarily compounds of the metals; and    d. calcining the filter cake from step (c).    
     
     
         2 . The process of  claim 1  wherein the waste spent pickling acid is waste spent galvanizing pickling acid.  
     
     
         3 . The process of  claim 1  wherein the waste spent pickling acid contains predominantly iron and zinc metal in a desired ratio.  
     
     
         4 . The process of  claim 3  wherein the desired ratio of zinc to iron is less than or equal to about 0.75.  
     
     
         5 . The process of  claim 3  wherein the desired ratio of zinc to iron is from about 0.5 to about 0.5854.  
     
     
         6 . The process of  claim 1  wherein more than one source of waste spent pickling acid is provided.  
     
     
         7 . The process of  claim 6  wherein a first source of spent pickling acid is provided having a ratio of zinc to iron from about 0 to about 1 and a second source of spent pickling acid is provided having a ratio of iron to zinc from about 0 to about 1.  
     
     
         8 . The process of  claim 7  wherein the first source of spent pickling acid comprises a blend of spent pickling acid from one or more sources.  
     
     
         9 . The process of  claim 7  wherein the second source of spent pickling acid comprises a blend of spent pickling acid from one or more sources.  
     
     
         10 . The process of  claim 7  comprising the additional step of blending the first and second sources of spent pickling acids prior to step (b).  
     
     
         11 . The process of  claim 10  wherein the blending step results in a blended spent pickling acid having a desired ratio of zinc to iron.  
     
     
         12 . The process of  claim 11  wherein the desired ratio of zinc to iron is less than or equal to about 0.75.  
     
     
         13 . The process of  claim 10  wherein the blending step takes place at temperatures ranging from about 40° F. to about 300° F.  
     
     
         14 . The process of  claim 1  wherein the reacting step comprises reacting the pickling acid from step (a) with alkali oxide, hydroxide or carbonate to make the slurry.  
     
     
         15 . The process of  claim 14  wherein the alkali oxide comprises one or a mixture from the group of sodium, calcium, potassium, lithium or magnesium.  
     
     
         16 . The process of  claim 14  wherein the reaction takes place at temperatures ranging from about 60° F. to about 400° F.  
     
     
         17 . The process of  claim 1  wherein the reaction takes place at temperatures designed to optimize the desired particle size of the solids.  
     
     
         18 . The process of  claim 14  wherein the reaction pressures are sufficient to maintain in solution the volatile components of the waste pickling acid.  
     
     
         19 . The process of  claim 18  wherein the reaction pressures are in the range of about 0 psig to about 100 psig.  
     
     
         20 . The process of  claim 14  wherein a reaction residence time is maintained to optimize the reaction slurry products.  
     
     
         21 . The process of  claim 20  wherein the reaction residence time is from about 0.1 hours to about 6 hours.  
     
     
         22 . The process of  claim 14  wherein a reaction residence time is maintained to optimize the pH of the reaction slurry product.  
     
     
         23 . The process of  claim 14  wherein the pH of the reaction slurry product is in the range of about 6.5 to about 8.  
     
     
         24 . The process of  claim 1  wherein the reacting step takes place in plug flow or stirred tank reactor operated either in batch or in continuous mode, or in a series of continuous stirred reactors.  
     
     
         25 . The process of  claim 1  wherein the filtration step is conducted at temperatures in the range of about 60° F. to about 300° F.  
     
     
         26 . The process of  claim 1  wherein the filtration step is optimized to prevent solids by-pass and enhance the clarity of the filtrate liquid.  
     
     
         27 . The process of  claim 1  wherein the filtration step is optimized to increase filtration rates.  
     
     
         28 . The process of  claim 1  wherein the filtration step is optimized to permit filtration rates of between about 0.06 gal/min/ft 2  and 0.5 gal/min/ft 2 .  
     
     
         29 . The process of  claim 1  wherein the filtration step is optimized to permit filter cake accumulation rates of between about 4 lb/hr/ft 2  and 50 lb /hr/ft 2 .  
     
     
         30 . The process of  claim 1  wherein the alkali chloride filtrate is substantially free of solids.  
     
     
         31 . The process of  claim 1  further comprising the additional step of washing the filter cake from step (c) at least once.  
     
     
         32 . The process of  claim 1  further comprising the step of washing, at least once, the product of step (d) comprising substantially oxides of iron and zinc.  
     
     
         33 . The process of  claim 1  further comprising the additional step of concentrating the liquid alkali chloride filtrate of step (c).  
     
     
         34 . The process of  claim 33  wherein the pH of the concentrating step is adjusted to about 6.5 to about 8.  
     
     
         35 . The process of  claim 33  further comprising the additional step of filtering the concentrated liquid alkali chloride filtrate.  
     
     
         36 . The process of  claim 1  wherein the calcining step oxidizes the filter cake to solids comprising a mixture of iron oxides, zinc oxides, alkali oxides, and/or various other partially hydrated oxides.  
     
     
         37 . The process of  claim 1  wherein the temperatures employed in the calcining step range from about 1100° F. to about 1500° F.  
     
     
         38 . The process of  claim 1  wherein the temperatures employed in the calcining step are sufficient to drive off substantially all free water, absorbed water and chemically bound water, as well as remaining chlorides.  
     
     
         39 . The process of  claim 1  further comprising the additional step of combining the filter cake solids separated in step (c) with an alkali material prior to the calcining step.  
     
     
         40 . The process of  claim 39  wherein the alkali material is selected from the group of inexpensive industrial alkali materials, including, sodium hydroxide, sodium carbonate, calcium carbonate, calcium hydroxide, calcium oxide or by-pass streams, aqueous or dry, containing the above, including, lime kiln dust.  
     
     
         41 . The process of  claim 39  wherein the solids separated in step (c) are combined with the alkali material in a weight ratio of solids to alkali adduct ranging from about 1:1 to 10:1 on a dry weight basis.  
     
     
         42 . The process of  claim 41  wherein the absorbency of the solids separated in step (c) and subsequently calcined in step (d) is higher than 0.35 grams of water per gram of calcined product.  
     
     
         43 . The process of  claim 1  wherein the product of the calcining step comprises substantially oxides of zinc and iron.  
     
     
         44 . The process of  claim 43  wherein at least some of the iron and zinc oxides are present in the form of zinc ferrate.  
     
     
         45 . The process of  claim 1  wherein the product of the calcining step comprises a powder of a particle size such that less than 15% of the particles are less than 6 micron equivalent diameter and do not pass through a 325 mesh screen) and 1.5% of the particles are greater than 75 micron equivalent diameter and do not pass through a 200 mesh screen.  
     
     
         46 . The process of  claim 43  wherein the density of the product is at least 4.5 and at most 5.5.  
     
     
         47 . A process of making a high density, high stability mixture of predominantly iron oxide, zinc oxide and zinc ferrate from waste spent galvanizing pickling acid comprising the steps of: 
 a. providing a first source of waste spent galvanizing pickling acid having a ratio of zinc to iron from 0 to 1;    b. providing a second source of waste spent galvanizing pickling acid having a ratio of iron to zinc from 0 to 1;    c. blending the first and second sources of pickling acid to achieve a ratio of zinc to iron of about 0 to about 0.75.    d. reacting the blended pickling acid from step (c) with alkali oxide, hydroxide or carbonate at temperatures and residence times to make a slurry consisting of optimum-sized solids comprising primarily iron and zinc and an aqueous liquid comprising primarily an alkali chloride;    e. filtering the slurry from step (b) to separate the aqueous alkali chloride from the solids thereby forming a liquid stream comprising alkali chloride filtrate that is substantially free of solids and a filter cake comprising primarily iron and zinc compounds; and    f. calcining the filter cake from step (c) at temperatures to oxidize the iron and zinc compounds comprising the filter cake to a product comprising substantially oxides of iron and zinc.    
     
     
         48 . A process of making a drilling fluid additive comprising the steps of: 
 a. providing a first source of waste spent galvanizing pickling acid having a ratio of zinc to iron from 0 to 1;    b. providing a second source of waste spent galvanizing pickling acid having a ratio of iron to zinc from 0 to 1;    c. blending the first and second sources of pickling acid to achieve a ratio of zinc to iron of about 0 to about 0.75.    d. reacting the blended pickling acid from step (c) with alkali oxide, hydroxide or carbonate at temperatures and residence times to make a slurry consisting of optimum-sized solids comprising primarily iron and zinc and an aqueous liquid comprising primarily an alkali chloride;    e. filtering the slurry from step (b) to separate the aqueous alkali chloride from the solids thereby forming a liquid stream comprising alkali chloride filtrate that is substantially free of solids and a filter cake comprising primarily iron and zinc compounds; and    f. calcining the filter cake from step (c) at temperatures to oxidize the iron and zinc compounds comprising the filter cake to a product comprising substantially oxides of iron and zinc.    
     
     
         49 . A high density, high stability metal oxide mixture manufactured by: 
 a. providing a waste spent pickling acid having a desired ratio of metals;    b. reacting the pickling acid from step (a) to make a slurry consisting of solids comprising primarily metals and an aqueous liquid comprising primarily an alkali chloride;    c. filtering the slurry from step (b) to separate the aqueous alkali chloride from the solids thereby forming a liquid stream comprising alkali chloride filtrate and a filter cake comprising primarily compounds of the metals; and    d. calcining the filter cake from step (c).    
     
     
         50 . A high density, high stability mixture of predominantly iron oxide, zinc oxide and zinc ferrate made from waste spent galvanizing pickling acid by the process of: 
 a. providing a first source of waste spent galvanizing pickling acid having a ratio of zinc to iron from 0 to 1;    b. providing a second source of waste spent galvanizing pickling acid having a ratio of iron to zinc from 0 to 1;    c. blending the first and second sources of pickling acid to achieve a ratio of zinc to iron of about 0 to about 0.75.    d. reacting the blended pickling acid from step (c) with alkali oxide, hydroxide or carbonate at temperatures and residence times to make a slurry consisting of optimum-sized solids comprising primarily iron and zinc and an aqueous liquid comprising primarily an alkali chloride;    e. filtering the slurry from step (b) to separate the aqueous alkali chloride from the solids thereby forming a liquid stream comprising alkali chloride filtrate that is substantially free of solids and a filter cake comprising primarily iron and zinc compounds; and    f. calcining the filter cake from step (c) at temperatures to oxidize the iron and zinc compounds comprising the filter cake to a product comprising substantially oxides of iron and zinc.    
     
     
         51 . A novel drilling fluid weighting agent of a high density, high stability mixture of predominantly iron oxide, zinc oxide and zinc ferrate made from waste spent galvanizing pickling acid by the process of: 
 a. providing a first source of waste spent galvanizing pickling acid having a ratio of zinc to iron from 0 to 1;    b. providing a second source of waste spent galvanizing pickling acid having a ratio of iron to zinc from 0 to 1;    c. blending the first and second sources of pickling acid to achieve a ratio of zinc to iron of about 0 to about 0.75.    d. reacting the blended pickling acid from step (c) with alkali oxide, hydroxide or carbonate at temperatures and residence times to make a slurry consisting of optimum-sized solids comprising primarily iron and zinc and an aqueous liquid comprising primarily an alkali chloride;    e. filtering the slurry from step (b) to separate the aqueous alkali chloride from the solids thereby forming a liquid stream comprising alkali chloride filtrate that is substantially free of solids and a filter cake comprising primarily iron and zinc compounds; and    f. calcining the filter cake from step (c) at temperatures to oxidize the iron and zinc compounds comprising the filter cake to a product comprising substantially oxides of iron and zinc.