Non-embedding method for heavy metal stabilization using beef bone meal and blast media

Abstract

Methods are disclosed for stabilizing a heavy metal in a heavy metal bearing paint residue to reduce leaching of the heavy metal from a waste subject to natural or induced leaching conditions by addition of environmentally safe, worker safe, and multi-media compatible stabilizing agent comprising beef bone meal. Beef bone meal is added to the blast media, and provides effective reduction of heavy metal content in waste leachate and effectively removes paint residue without causing visible embedding on the substrate surface, which meets the SSPC SP10 criteria for surface preparation prior to painting. The methods described herein may be used outside of or within an OSHA containment building or collection device. The resultant stabilized paint residue and spent blast media mixture is suitable for on-site reuse, off-site reuse, or disposal as RCRA non-hazardous waste.

What is claimed is: 
     
         1 . A method for stabilizing a heavy metal in a heavy metal-containing paint residue to reduce leaching of the heavy metal therefrom when said paint residue is generated into paint waste and exposed to natural or induced leaching conditions, comprising:
 contacting a heavy metal-containing paint residue that is painted on a substrate with a mixture comprising paint removal blast media and a stabilizing agent comprising beef bone meal in an amount effective to reduce leaching of the heavy metal to a non-hazardous level, thereby forming a stabilized paint waste and a blast-cleaned substrate;   wherein the blast-cleaned substrate is not visibly embedded with stabilizing agent and paint removal blast media.   
     
     
         2 . The method of  claim 1 , wherein the paint residue is contacted with the mixture within an Occupational Safety and Health Administration (OSHA) containment structure. 
     
     
         3 . The method of  claim 1 , wherein the paint residue is contacted with the mixture within a collection device comprising an exhaust air filtration cyclone or baghouse. 
     
     
         4 . The method of  claim 3 , wherein contacting the paint residue with the mixture occurs prior to exposure of the paint residue to an exhaust air filtration cyclone or baghouse. 
     
     
         5 . The method of  claim 1 , wherein the paint residue is contacted with the mixture within a vacuum collection device after exposure of the paint residue to an exhaust air filtration cyclone or baghouse and before the discharge of the paint residue to an accumulation tank. 
     
     
         6 . The method of  claim 1 , wherein the paint residue is contacted with the mixture within a vacuum collection device after exposure of the paint residue to an exhaust air filtration cyclone or baghouse and during the discharge of the paint residue to an accumulation tank. 
     
     
         7 . The method of  claim 1 , wherein the paint residue is contacted with the mixture within a vacuum collection device during exposure of the paint residue to an exhaust air filtration cyclone or baghouse. 
     
     
         8 . The method of  claim 1 , wherein the stabilizing agent is used in pressurized blast pots or a venturi-type pickup apparatus. 
     
     
         9 . The method of  claim 1 , wherein paint removal blast media is a dry blasting media, a semi-wet sponge blasting media or high pressure water. 
     
     
         10 . The method of  claim 1 , wherein the stabilizing agent is in the form of a dry powder, a dry granule, or as a slurried mixture. 
     
     
         11 . The method of  claim 3 , wherein the mixture comprising paint removal blast media and stabilizing agent comprises beef bone meal at 2% by weight in mining tailing crushed rock. 
     
     
         12 . The method of  claim 1 , wherein the stabilized paint waste comprises a heavy-metal containing solid phase mineral exhibiting low toxicity and low solubility under natural or induced leaching conditions. 
     
     
         13 . The method of  claim 12 , wherein the solid phase mineral is Pb 3 (PO 4 ) 2 . 
     
     
         14 . The method of  claim 13 , wherein the mineral has low solubility in water and simulated rainwater extract and meets the criteria for resistance to leaching under SPLP leaching test USEPA method 1310. 
     
     
         15 . The method of  claim 1 , wherein the blast-cleaned substrate is compatible with subsequent application of at least one of paint surface cleaner, primer and paint. 
     
     
         16 . The method of  claim 1 , wherein the stabilizing agent stabilizes heavy metals and reduces leaching of heavy metals in paint residue, spent paint removal blast media, substrates and residual airborne or deposited dust. 
     
     
         17 . The method of  claim 1 , wherein the resultant paint waste and mixed spent paint removal blast media and stabilizing agent does not classify as characteristic hazardous waste according to the Toxicity Characteristic Leaching Procedure, Test Method 1311. 
     
     
         18 . The method of  claim 1 , wherein the mixture further comprises bone meal, pork bone meal, fish bone meal, fishbone, phosphate rock, calcium phosphates, Portland Cement, cement kiln dust, lime kiln dust, lime, silicates, sulfides, iron, quicklime, phosphate complexers chlorides, iron and/or aluminum; wet process amber phosphoric acid, wet process green phosphoric acid, coproduct phosphoric acid solution from aluminum polishing, technical grade phosphoric acid, hexametaphosphate, polyphosphate, calcium orthophosphate, superphosphates, triple superphosphates, single superphosphate, ordinary superphosphates, crop production phosphates, phosphate feeds, phosphate fertilizers, tetrapotassium polyphosphate, monocalcium phosphate, monoammonia phosphate, diammonium phosphate, dicalcium phosphate, dicalcium phosphate dihydrate powder, tricalcium phosphate, trisodium phosphate, salts of phosphoric acid, or combinations thereof. 
     
     
         19 . A method for stabilizing a heavy metal in mixed heavy metal-containing paint residue and spent paint removal blast media to reduce leaching of the heavy metal under natural or induced leaching conditions, comprising:
 contacting mixed heavy metal-containing paint residue and paint removal blast media with beef bone meal in an amount effective to reduce leaching of the heavy metal to a non-hazardous level, thereby forming a stabilized waste.   
     
     
         20 . A method of reducing the solubility of mixed heavy metal bearing paint residue and spent paint removal media and meeting the Society for Protective Coatings standard of no-visual embedding of stabilizer or media particles on blast cleaned substrate, comprising contacting the mixed paint residue and spent paint removal media with at least a stabilizing agent comprising beef bone meal in an amount effective in reducing the leaching of heavy metal to a level no more than non-hazardous levels as determined in an EPA TCLP test, performed on the stabilized material or waste, as set forth in the Federal Register, vol. 55, no. 126, pp. 26985-26998 (Jun. 29, 1990), and selecting the shape and size of the beef bone meal such that the resulting stabilizer and blast media meets project criteria of no naked-eye observable substrate embedding.