METHOD FOR IMPROVING TRANSPORT AND HANDLING OF DUST EMITTING SOLIDS MATERIALS

Abstract

Methods are provided for controlling fugitive dust emissions from a variety of granular or particulate solids materials such as coal dust. A first treatment of cationic polymer or cationic copolymer is applied to the dust. The dust is then loaded onto an open bed rail car or the like. A topping treatment comprising an aqueous dilute polymer solution or polymer latex emulsion or dispersion is applied to the exposed coal layer in the rail car.

Claims

1. Method for suppressing fugitive duct emission from a granular, or particulate solid material comprising: (1) applying a cationic polymer or copolymer to said solid material; (2) loading said solid material from said step (1) into a transport vehicle, and (3) applying a topping treatment of polymer to said solid material.

2. A method as recited in claim 1 wherein said topping treatment comprises an aqueous solution of water soluble polymer or a latex emulsion or dispersion of polymer.

3. A method as recited in claim 1 wherein after said step (3), said granular or particulate solid material exhibits greater than 85% improvement in dust suppression when compared to untreated samples of said granular or particulate solids under wind conditions of 35-45 mph for five minutes.

4. A method as recited in claim 3 wherein said improvement in dust suppression is greater than 95%.

5. A method as recited in claim 2 wherein said solid material comprises a granular or particulate material chosen from coke, urea, mineral ores, mineral concentrates, fly ash, coal combustion residue, phosphate rock, fertilizer, limestone, crushed stone, aggregate, sand, wood chips, waste derived fuel, hog fuel, iron ore pellets, and coal.

6. A method as recited in claim 5 wherein said solid material is coal dust and said transport vehicle is a rail car; said step (3) comprising application of said topping treatment over an exposed layer of said coal disposed in said rail car in an amount of less than about three gallons of said polymer latex emulsion or dispersion per rail car.

7. A method as recited in claim 6 wherein said step (1) comprises applying a foam containing said cationic polymer or copolymer to said coal dust, said cationic polymer or copolymer comprising a member selected from the group consisting of polyamines, polyquaternary ammonium polymers, and copolymers, melamine/formaldehyde polymers, diallyldimethyl ammonium chloride polymers, di-ethylene-triamine/adipic acids/epichlorohydrin polymers, amino-methylated polyacrylamide and cationic copolymers of acrylamide.

8. A method as recited in claim 7 wherein said foam containing said cationic polymer or copolymer is fed to said coal dust at a weight percent of about 0.05-30.0% of said foam per ton of said coal dust.

9. A method as recited in claim 8 wherein said foam contains about 0.05-20.0% by weight of said cationic polymer or copolymer.

10. A method as recited in claim 9 wherein in said step (3) said topping treatment is sprayed onto said exposed layer of coal dust at a rate of about 1-3 gallons of said topping treatment (actives basis) per rail car.

11. A method as recited in claim 10 wherein said topping treatment comprises a member selected from the group consisting of styrene-acrylic copolymers, styrene-butadiene copolymers, vinyl acrylic copolymers, acrylic polymers, methacrylate-acrylate ister copolymers, polyvinyl acetate polymers, ethylene-polyvinyl acetate copolymers, vinyl acetate-acrylic copolymers, and polyacrylamide polymers and copolymers.

12. A method as recited in claim 11 wherein said cationic polymer or copolymer is an amino-methylated polyacrylamide.

13. A method as recited in claim 11 wherein said cationic polymer or copolymer is a diethylene-triamine/adipic acid/epichlorohydrin polymer.

14. A method as recited in claim 11 wherein topping treatment is a said latex emulsion or dispersion comprising ethylene-polyvinyl acetate copolymer.

Description

DETAILED DESCRIPTION

[0021] In accordance with one exemplary embodiment, methods are provided for suppressing fugitive air borne dusts from a variety of finely divided particulate or granular materials. Although the invention will deal mainly with dust suppression of coal dust particles, the artisan will appreciate that the solid particulate or granular dusts to be treated can comprise a variety of particles such as coke, urea, mineral ores, mineral concentrates, fly-ash, coal combustion residue (CCR), phosphate rock, fertilizers, limestone, crushed stone, aggregates, sand wood chips, waste derived fuels (WDF), hog fuel, and iron ore pellets.

[0022] One aspect of the invention is directed to a two step dust dissemination suppression treatment wherein a body feed treatment of dust control additive is made prior to the loading of the dust into a transport vehicle such as a rail car or truck. Then, about 1-3 pounds of a latex based topper treatment is applied to the dust prior to or upon loading of the dust to the transport vehicle. In most cases, the topper treatment is made to the dust particles after same have been loaded to a rail car, and the topper treatment is made, as the name suggests, to the top layer of exposed coal lying in the rail car.

[0023] In some aspects of the invention, foamed application of a cationic polymer or polymers is first made as the body treatment followed by a topper application to the so-treated dust particles. The cationic polymers or cationic copolymers can be chosen from a wide variety of material including, but not limited to, water soluble polymers and copolymers of [0024] Polyamines and polyquaternary ammonium salts [0025] Melamine/formaldehyde polymer [0026] Diallydimethyl ammonium chloride polymer [0027] Diethylene-triamine/adipic acid/epichlorohydrin polymer (preferred material) [0028] Amino-methylated polyacrylamide (preferred material) [0029] Cationic copolymers of acrylamide

[0030] After application of body feed and placement of coal into the rail car, car topper material is applied as a dilute solution in water, at the rate of less than three pounds per rail car of car topper material, preferably one to two pounds per rail car (actives basis of polymer in latex emulsion or dispersion). The solution application rate of the dilute car topper material will be in the range of 10 to 25 gallons/rail car, preferably 15 to 20 gallons/rail car.

[0031] Car topper materials can include polymeric solutions or latex emulsions or dispersion comprising, but not limited to the following polymers: [0032] Styrene-acrylic copolymers [0033] Styrene-butadiene copolymers [0034] Vinyl-acrylic copolymers [0035] Acrylic polymers [0036] Methacrylate-acrylate ester copolymers [0037] Polyvinyl acetate polymers [0038] Ethylene-polyvinyl acetate copolymers (preferred material) [0039] Vinyl acetate-acrylic copolymers [0040] Polyacrylamide polymers and copolymers

[0041] In some aspects of the invention, the body feed treatments are applied in foam form. The body feed water soluble cationic polymers or copolymers may be supplied initially in concentrate form which is then diluted prior to application as a foam. The body feed treatment concentration, in percent cationic polymer by weight foam, can range from about 0.05% to 20.0%0/and is preferably from about 0.1 to 10.0%. The feed rate of foam onto the substrate, on a weight percent basis, can range from about 0.05 to 30.0% and is preferably from about 0.1 to 15.0%.

[0042] The foam for the body feed dust control treatment may be formed and applied via conventional techniques such as those disclosed in U.S. Pat. No. 4,440,220 (Cole), the contents of which are hereby incorporated by reference. A suitable foaming agent and water are included in the body feed treatment. The foaming agents may be anionic, cationic, or amphoteric. One particularly noteworthy anionic surfactant is a C.sub.14-C.sub.16 alpha olefin sulfonate.

Examples

[0043] In order to assess the efficacy of the treatment methods in coal dust emission, the following tests were performed using the procedure set forth below.

Laboratory and Test Method:

Sample Collection and Preparation:

[0044] Coal samples were obtained from the mine site either not treated with body-feed as controls or treated with body-feed. Prior to application of car-topper treatment, the coal is screened to inch0 ( minus). Only the minus fraction is used for the test.

Topper Treatment:

[0045] Approximately eight pounds of the coal is placed in a sample tray (14.510.52 deep). The sample tray is placed on a guide rail assembly, wherein the tray is horizontally moved at fixed speed under a fixed spray nozzle, via a servo-motor and pulley. The topper treatment solution is sprayed across the width of the sample while the tray is moved along the guide rail. The entire topper treatment solution is applied in a single coat. The spray system has an adjustable pump that can vary the spray rate to provide equivalent of 10 to 30 gallons/rail-car of topper solution.

Solar Stress and Driving:

[0046] After topical treatment, the tray is placed directly under heat lamps to simulate solar stress. After heating the sample for a minimum of two hours, the tray continues to dry overnight (for 12 to 16 hours).

Wind Tunnel Test:

[0047] The sample tray is positioned in the middle of a 481212 (LWH) Wind Tunnel. The air current is created by an electric blower at the inlet of the wind tunnel. The tray is placed on an angle so that the entire surface is subject to the air current. A turbine-type anemometer is used to measure the actual wind speed in the tunnel during the test. At the exit of the tunnel, a (pre-weighed) pleated fabric filter is used to collect any airborne dust that is dislodged from the sample tray. At the end of the test, the dust on the filter is weighed and recorded. Wind tunnel test duration was 300 seconds, at a wind speed of 35 to 45 mph.

[0048] Results are shown in Table 1:

TABLE-US-00001 TABLE 1 40 mph for 300 seconds Dust Collected (g) % Dust Suppression Untreated Powder 35 0.0% River Basin Coal Bodyfeed 21 40.0% 0.2 gals/car Topper 6 82.9% without Bodyfeed Bodyfeed + 0.2 1 97.1% gal/car Topper Bodyfeed = amino methylated polyamine Cationic polymer and C.sub.14-C.sub.16 alpha olefin sulfonate surfactant (foaming agent) 1:1 actives bases; foamed solution is fed to coal at about 1.0 wt % solution in water Topper = vinyl acetate/ethylene copolymer latex (VA)

[0049] Standard latex emulsion or dispersion polymers applied as dust control agents require up to 10 pounds latex per rail car. Certain aspects of the present invention, however, require only one to three pounds of latex solution applied to the top of the coal mass in the rail car when combined with a prior body feed application of cationic polymer or copolymer. This represents considerable cost savings.

[0050] From the above example, in one embodiment, the combination of body feed treatment followed by topper treatment results in percent dust suppression of greater than 85% when compared to untreated coal dust samples. Indeed, as per the above example, greater than 95% dust suppression can be achieved in some instances under wind speed conditions of 35-45 mph for five minutes.

[0051] While the present invention has been described with respect to particular examples, it is apparent that numerous other form and modifications of the invention will be obvious to those skilled in the art. The appended claims and this invention should be construed to cover all such obvious forms and modifications which are within the spirit and scope of the present invention.