Center for
By-Products
Utilization
PRELIMINARY DRAFT REPORT
LIME KILN DUST (LKD)
By Tarun R. Naik and Fethullah Canpolat
Report No. CBU-2004-04
REP-548
February 2004
A CBU Report
Department of Civil Engineering and Mechanics
College of Engineering and Applied Science
THE UNIVERSITY OF WISCONSIN – MILWAUKEE
TABLE OF CONTENTS
LIME KILN DUST (LKD) ...........................................................................1
INRTODUCTION .........................................................................................1
LIME ...............................................................................................................2
National Lime Association Specification for Road Stabilization ................................... 2
Calcium Oxide or Quicklime .......................................................................................... 2
Uses of Lime ................................................................................................................... 4
Environmental Uses .................................................................................................... 4
Flue Gas Desulfurization Solid Wastes Disposal ....................................................... 5
USES OF LIME KILN DUST .....................................................................5
Typical Lime Kiln Dust ( Calcium Oxide) Specification [4] ..................................... 5
Use of kiln dust with quicklime for effective municipal sludge pasteurization and
stabilization with the N-Viro Soil process .................................................................. 6
Soil substitute from alkaline stabilization ................................................................... 6
Geotechnical evaluation of dredged material from Newark harbor ............................ 7
Soil stabilization utilizing alternative waste materials................................................ 8
Thaumasite formation in stabilized coal combustion by-products ............................. 8
References .......................................................................................................9
i
LIME KILN DUST (LKD)
INRTODUCTION
Most people are environmentalists: they want clean air and water their families and
friends. Industrialists are faced with the task of achieving a clean environment in a cost
effective way while producing necessary chemicals such as lime. Lime is one of the most
important chemicals such as lime. Lime is one of the most important chemicals used to
reduce pollution. The production of lime is an intense process where limestone rock is
heated to high temperatures by burning fossil fuels [1].
This process emits the products of combustion, moisture and dust. The waste gases from
the process are usually filtered through fabric dust collectors tom remove dust. The
important concerns when purchasing fabric filter bag collectors are emission regulations,
capital cost and operating cost [1].
It is very interesting how, over the years, the predominate uses of lime have changed. Just
several years ago the steel industry was demanding research on better ways to
manufacture lime to meet their needs in the newer basic oxygen furnaces, Steel went its
way, but now environmental stresses are at the forefront and industry is seeking
innovative ways to protect the world. Of course, lime is playing a very important role in
the clean up of air, land, and water. As time moves on, the age old chemical, lime,
remains a major factor in the life of man [2].
1
LIME
National Lime Association Specification for Road Stabilization
1. For either high calcium or dolomitic hydrated lime, a minimum of 95% total oxide
content (CaO + MgO) on a non-volatile basis is required.
2. Carbon Dioxide (5 - 7% maximum, depending upon where sampled)
3. Particle Size - 85% passing #200 mesh sieve [3].
Calcium Oxide or Quicklime
Chemical lime is a term designating a type of quick or hydrated lime.
Calcium hydroxide: low in impurities and possessing a high degree of reactivity making
it suitable for use in chemical processes. Commercially, chemical lime is obtained
through the controlled calcination of high quality limestone. Quicklime, the product of
calcination, consists of the oxides of calcium and magnesium, and in this country it is
available in three forms.
High calcium quicklime: containing usually 0.5 to 2.5 percent magnesium oxide.
Dolomitic quicklime: containing usually 35 to 40 percent magnesium oxide.
Magnesium quicklime: containing usually 5 to 10 percent magnesium oxide.
2
Chemical lime is a white solid having a crystalline structure. Quicklime is highly
reactive with water, generating considerable heat in the hydration process. This material
will react with the moisture in the air, and as such, it has found application as a desiccant.
In the presence of moisture, the lime reacts slowly with the carbon dioxide of the air,
forming water insoluble carbonates. As a chemically active material it is desirable to
reduce atmospheric exposure during handling and storage to a minimum.
Quicklime is available by the carload, in bulk dump or tanker, and in 50 Ib. paper bags
and one ton bulk bags and a number of more or less standard sizes as follows:
Lump lime: the product with a maximum size of eight inches in diameter.
Crusted or pebble lime: the product ranging in size from about 1/4 to 2 inches.
Ground lime: the product resulting from grinding the larger sized material. A typical size
is substantially all material passing a No. 8 sieve and 40 to 60 percent passing a No. 100
sieve.
Pulverized lime: the product resulting from a more intense grinding than is used to
produce ground lime: a typical size is all material substantially passing a No. 20 sieve and
85 to 95 percent passing a No. 100 sieve.
Pelletized lime: one inch sized pellets or briquettes, molded from quicklime fines [3].
3
Uses of Lime
Metallurgy: Steel Manufacture, Steel Products Manufacture, Magnesium Manufacture,
Alumina Manufacture, Ore Flotation and Non-Ferrous Metal Smelting.
Pulp and Paper: Sulfate Process, Sulfite Process, Bleaching, Precipitated Calcium
Carbonate, Strawboard Manufacture, and in the treatment of pulp and paper mill liquid
wastes, as a coagulant in color removal.
Chemicals: Alkalis, Calcium Carbide and Cyanimide, Petrochemicals, Bleaches, Dye and
Dyestuff Intermediates and Coke-By-Products. In addition, it is used in the purification of
citric acid, glucose and dextrin: metallic calcium; soda-lime, an adsorbent; and for
countless other minor or isolated purposes, such as for CO2 absorption [3].
Environmental Uses
Water Treatment: Scope, Softening, Purification, Coagulation, Neutralization of Acid
Water, Silica Removal and Removal of Other Impurities,
Sewage Treatment: Maintain proper pH and Stabilizing Sewage Sludge.
Industrial Trade Wastes: Treatment of industrial trade wastes to abate pollution from
Steel and Metal Fabricating Plants, Chemical and Explosives Plants, Acid Mine
Drainage, Paper and Fibers, Food Plants and in clarifying "water gas" acid waste
effluents [3].
4
Flue Gas Desulfurization Solid Wastes Disposal
Ceramic Products: Glass, Refractories, and in the production of whiteware pottery, lime
is sometimes employed to bind the kaolin and ball clays present. '
Building Materials: Calcium Silicate Brick, Concrete Products, Miscellaneous Building
Units, and Insulation Materials.
Protective Coatings: Pigments, Water Paints, and Varnish.
Food and Food By-Products: Dairy Industry, Sugar Industry, Animal Glue and Gelatin
Industries, Baking Industry, and CA (controlled atmospheric) Storage of Fresh Fruit and
Vegetables. All tortillas are made with lime treatment.
Miscellaneous Uses: Petroleum, Leather, and Rubber [3].
USES OF LIME KILN DUST
Typical Lime Kiln Dust ( Calcium Oxide) Specification [4]
Chemical Analysis
CaO
MgO
SiO2
Al2O3
Fe2O3
S
Available CaO
Percent
57.80
0.07
4.00
2.50
0.90
0.48
29.30
Physical Analysis
Percent Passing
1/2"
100.0
20 Mesh
100.0
60 Mesh
99.8
100 Mesh
99.5
200 Mesh
93.6
Bulk Density = 83.6 lbs./cu.ft.
5
Use of kiln dust with quicklime for effective municipal sludge pasteurization
and stabilization with the N-Viro Soil process
Burnham et al. [5] studied on use of kiln dust. They study to addresses the impact that
treatment of the sludge with lime and kiln dust will have on microorganisms survival and
regrowth, as well as metal availability to plants and groundwater. With the alternatives
for sludge processing changing because of the public awareness of problems of dumping,
either in landfills or oceans, the treatment of municipal sludges with cement kiln dust
offers a technically solid solution to the current dilemma of how to treat municipal sludge
so that it is safe, acceptable to the public, and a useful, even saleable, agrinomic
commodity.
Soil substitute from alkaline stabilization
Anaerobically digested biosolids are processed with a combination of fluidized bed coal
fly ash and lime kiln dust at the Bayview N-Viro facility in Toledo, Ohio. The fly ash is
composed primarily of CaO, gypsum and CaCO sub 3, while the lime kiln dust is
primarily CaO, MgO and dolomite.
After the 12 hour heat pulse, the product is
windrowed daily for three days and then stockpiled for shipment. The combination of
treatments results in complete pathogen destruction, which qualifies the process as Class
A under EPA 503 rules [6].
There was no observed seed germination in N-Viro Soil in the standard germination test
until month six.
Both month six and month seven samples exhibited excellent
germination (75 and 72 percent of that observed in sand). When compared to the decline
6
in those parameters hypothesized to inhibit seed germination, it would appear that the
likely limiting causative factor was free NH sub 3, because maximum declines in pH, EC
and fatty acids occurred prior to month six, while free NH sub 3 did not disappear until
the six month sampling. It is likely, however, that all of the factors contributed to seed
germination inhibition, particularly in the less cured samples. The content of Ca(OH) sub
2 itself is not likely to be inhibitory; its effects are exhibited indirectly in pH and soluble
salt levels [6].
Germination of six species in the greenhouse was excellent when compared to sand with
no significant differences between the two growth media. This confirms the results of the
standard germination test but for a wider range of species [6].
Geotechnical evaluation of dredged material from Newark harbor
Maher et al. [7] reported that by the year 2000, approximately 20,914,000 cubic yards of
material will be dredged in the Port of New York and New Jersey region. Under the new
joint dredging plan for this region, 9,114,000 cubic yards of this material is classified as
Category II and III, non-ocean disposal material.
Without ocean disposal, the
contaminated material must be stabilized of contaminants before any placement can
occur. The Newark Bay dredged material was treated with three different pozzolanic
admixtures prior to laboratory tests; portland cement (PC), cement kiln dust (CKD) and
lime kiln dust (LKD). Each mix was then tested for material properties and strength
characteristics using soil classification, resilient modulus, and triaxial compression tests.
The shear strength of the treated material was found to be sufficient for a wide range of
geotechnical applications such as embankments, subgrades of roadways, and structural
7
and non-structural fills.
Toxicity Characteristic Leaching Procedure (TCLP) tests
conducted on the treated material found no detectable levels of contaminants (heavy
metals, PCB's, etc.) present once stabilization occurred.
Soil stabilization utilizing alternative waste materials
Heckel et al.[8] study considers the use of four by-products, three of which are waste, as
alternatives to a currently acceptable high calcium lime kiln dust (LKD) for subgrade soil
stabilization.
The alternative materials include a dried lime kiln sludge (DLKS), a
hydrated lime by-product (HLB), an ASTM Type C fly ash (TCFA) and fly ash that does
not meet the requirements of ASTM C 618 (non-spec fly ash, NSFA). The lime byproducts, including the control LKD, were individually mixed with four different soil
types. The fly ashes were mixed with only one soil. Test results include the moisturedensity relationships, bearing values, uncured compressive strengths, swell potential, and
plasticity index for treated and untreated soils. The results indicate that the use of these
waste by-products for soil stabilization could: 1) result in benefits comparable with the
accepted LKD, 2) help reduce the amount of wastes being disposed of annually, and 3)
open the market to alternative materials, thereby resulting in more competitive prices.
Thaumasite formation in stabilized coal combustion by-products
The by-products of the desulfurization process in a spray drier usually contain a mixture
of hannebachite (CaSO3 1/2H2O), gypsum (CaSO4 · 2H2O), and the finer fraction of the
fly ash. This material was mixed with an additional fly ash and stabilized by adding
about 3 wt% lime kiln dust (LKD). The stabilized product was used either as a structural
8
fill or was left in the storage yard for several years. Samples extracted from these sites
were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM).
The analytical results show the formation of thaumasite (Ca3Si(OH)6(CO3)(SO4 ) ·
12H2O), ettringite (Ca6Al2(SO4)3(OH)12< /sub> ·26H2O), and an intermediate phase with
varying chemical composition of calcium, aluminum, silicon, and sulfur. [9].
References
1. Biege, N., Smith, D., Lindquist, W., 1997, “Lime kiln dust collectors: making the
right choice,” World Cement, Vol. 28, No. 2, pp. 22-27].
2. Walker, D. D., Jr., Hardy, T. B., Hoffman, D. C. and Stanley Dewey, D., 1992, “
Innovativations and uses for lime,” ASTM Publication, Philadelphia, PA. p. vii.
3. http://www.peterschemical.com/calcium_oxide_or_quicklime.htm
4. http://www.peterschemical.com/Lime%20Kiln%20Dust%20%20Specifications.htm
5. Burnham, J. C.; Hatfield, N., Bennett, G. F.; Logan, T. J., 1992, “Use of kiln dust
with quicklime for effective municipal sludge pasteurization and stabilization
with the N-Viro Soil process,” ASTM Special Technical Publication,
Philadelphia, PA, No.1135, pp. 128-141.
6. Logan, T. J, Harrison, B. J, Goins, L. E., and Hatfield, N., 1995, “Soil substitute
from alkaline stabilization,” BioCycle, Emmaus, Vol. 36, No. 9, pp. 80-81.
7. Maher, M.H., Bennert, T., Jafari, F., and Aagaard, P, 1997, “Geotechnical
evaluation of dredged material from Newark harbor,” Proceedings of the 13th
International Conference on Solid Waste Technology and Management, Widener
9
University, School of Engineering, Philadelphia, PA, USA, Part 1 (of 2), Vol. 1,
p. 8.
8. Heckel, G. and Wahab, R., 1996, “Soil stabilization utilizing alternative waste
materials,” Proceedings of the Materials Engineering Conference, Washington,
DC, Materials for the New Millennium, ASCE, Vol. 1, pp. 318-327.
9. Sahu, S., Brown, S. A., Lee, R. J., 2002, “Thaumasite formation in stabilized coal
combustion by-products,” Cement and Concrete Composites, Elsevier Science
Ltd., Vol. 24, No. 3-4, pp. 385-391.
10