the present invention provides a method of inhibiting dust generation and biological activity in bulk solid materials . the method of the present invention may employ the application of a so called &# 34 ; one drum treatment &# 34 ;. the treatment is composed of a foam which includes dust control agents and pesticidal agents . the bulk solids which are treated by the present invention include materials which tend to generate dust during manufacture , storage and handling and which also are desirably treated for control of biological activity . examples include dried sludge , coal , animal feed , grain and absorbants such as cat litter . the dust and pesticidal agents are applied as a foam which can be intimately mixed with the material to be treated . the use of foam as a distribution medium allows effective application of the control agents to bulk solids . the control agents of the present invention are thereby applied to essentially the entire surface of the bulk solid as opposed to surface treatments such as spraying a coal pile . the foam of the present invention may be composed of anionic , nonionic and / or cationic surfactants in aqueous solutions . the generation of the foam may be by any suitable means such as described in u . s . pat . no . 4 , 400 , 220 , cole , the contents of which are hereby incorporated by reference . the use of such foams will provide dust control most effectively when applied during manufacturing and transfer operations . exemplary surfactant foaming agents include alkyl aryl sulfonate , alkyl ether sulfate , alpha olefin sulfonate , alpha sulfo methyl ester , alkyl sulfosuccinate , alkanolamide , amine oxide , and betaines . for effective dust control during storage , water and / or oil based binders such as mineral or vegetable oils , elastomeric and water soluble polymers and lignosulfonate compositions may be desirable . such binders or extenders provide more effective residual dust control . the pesticidal agent ( s ) portion of the present invention may include water and / or oil based biocides , fungicides , and pesticides . the use of such pesticidal agents in combination with a foam dust control agent provides for effective distribution over the surface area of the bulk solid . further , the application of a pesticidal agent in a foam allows extremely efficient distribution of a relatively small amount of active material . for example , in typical prior art grain or animal feed treatment , large volumes of relatively concentrated gaseous fumigants are employed to distribute the fungicide throughout the mass of the grain . in the method of the present invention , because essentially all of the biological control agent ends up on the surface of the bulk solid , rather than escaping to the atmosphere , lower volumes and concentrations of treatment material may be employed . exemplary pesticidal agents include , but are not limited to , n - alkyl dimethyl benzyl ammonium chloride ( and other quaternary ammonium biocides ), dodecyl guanidine hydrochloride , acrolein ( produced in situ from suitable precursors ), methylene bisthiocyanate , bis trichloromethyl sulfone , bromo - nitrostyrene , 2 , 2 - dibromo - 3 - nitrilopropionamide , 5 - chloro - 2 - methyl - 4 - isothiazolin - 3 - one ( with 2 - methyl - 4 - isothiazolin - 3 - one ), 2 - bromo - 2 - nitro - propane - 1 , 3 - diol , and decyl thioethyl amine , either alone or in combination . the combination of a formulation containing methylene bisthiocyanate and bromo - nitrostyrene ( slimicide c - 41 ) and an oil based binder ( betz dg - 1259f ) emulsified in water with a surfactant foaming agent ( flowpro ® 1105 ) has been found to provide effective dust control as well as odor control when applied as a foam to a coal / sludge mixture . the commercial products ( slimicide c - 41 , betz dg - 1259f , and flowpro 1105 ) are available from betz laboratories , inc ., trevose , pa . such coal / sludge mixtures are kiln dried and employed as inexpensive fuels in cement plants or similar applications . the application of a fungicide to grain in an aqueous dust control foam would be effective at inhibiting the formation and dissemination of grain dust . further , such a combination would provide effective control of insect damage . the highly efficient application of a fungicide such as acrolein generated in situ from a suitable precursor , see u . s . pat . no . 4 , 851 , 583 bockowski et al in a foam would provide effective control at reduced active treatment levels . the invention will now be further described with reference to a number of specific examples which are to be regarded solely as illustrative and not as restricting the scope of the invention . a sludge / coal mixture was dried in a kiln and treated with a foamed emulsion comprising : an untreated sludge / coal mixture exhibited a high level of dust generation and a strong odor and visible biological activity believed to be fungus or mold . the sludge / coal mixture treated with foamed emulsion exhibited a very low level of dust generation and no odor or visible evidence of biological activity . betz ® slimicide c - 41 is a broad spectrum biocide available from betz laboratories inc ., of trevose , pa . the active biocidal agents are beta - bromo - beta nitrostyrene ( bns ) at 9 . 2 % and methylene bis thiocyanate ( mbt ) at 4 . 9 %. ( see u . s . pat . no . 4 , 579 , 665 , davis et al and u . s . pat . no . 3 , 898 , 343 , swered et al ). all percentages are in weight percent . the combination of the present invention would be similarly effective at inhibiting the formation of biologically induced acid waste , such as acidic leachate called acid mine drainage . when coal or coal refuse is stored in piles , aqueous drainage or leachate often is acidic . the acidic nature of the leachate is related to biological activity within the coal pile . similar acidic waste can be found in other ore and mineral piles . surfactant based biocides such as alkyl benzene sulfonates , and alkyl sulfates sprayed onto the coal piles have been shown to reduce the bacteria and inhibit the acid mine drainage . dust dissemination is also a problem in such coal storage piles . the application of foam dust control agent ( s ) with a pesticidal control agent ( s ) and a binder during formation of such piles would provide effective dust control and inhibit biological activity throughout the pile , not just at the surface . grains and animal feed are often treated with mineral oil and / or water for dust control in a separate application from fumigation . typically , post harvest pesticides such as methyl chloride , aluminum phosphide , or certain organophosphates are employed for fumigation . the application of a foam dust control agent which includes a dust control extender and a post harvest pesticide during handling of the grain will provide more effective control than prior art treatments . the method of the present invention will effectively control grain dust as well as insect damage . in the treatment of grains and animal feed , it is desirable to limit the moisture content of the foam to avoid the undesirable addition of moisture to the material . while this invention has been described with respect to particular embodiments thereof , it is apparent that numerous other forms and modifications of this invention will be obvious to those skilled in the art . the selection of appropriate surfactants , foam extenders and biological control agents is primarily dependent upon the bulk solids to be treated and compatibility of the components . the appended claims and this invention generally should be construed to cover all such obvious forms and modifications which are within the true spirit and scope of the present invention .
a foam carrier for a dust control agent and a pesticidal material is provided to control fugitive dust dissemination and biological activity in bulk / granular solids .