JP2008538347A5 - - Google Patents

Description

Synthetic aggregates containing sewage sludge and other waste and methods for producing such aggregates

  The present invention relates to synthetic aggregates, particularly synthetic aggregates comprising sewage sludge and silicon aluminum materials, and synthetic aggregates comprising a combination of low calcium and high calcium containing silicon aluminum materials.

  Aggregate is an essential component of concrete, masonry and cavity-filled insulation. Other uses of aggregates include filler aids or horticultural aggregates. Aggregates may be from natural sources with minimal processing or natural materials that have been heat treated. Aggregates may be synthetic. For example, aggregates from natural sources such as quarries, underground shafts and riverbeds are usually composed of rock fragments, gravel, stones and sand, which should be used after being crushed, washed and sized as needed Can do. Aggregates from natural materials that can be used to form aggregates include clay, shale and slate, which are fired to expand the material. For example, OPTIROC and LECA are examples of commercially available expanded clay aggregates. Synthetic aggregates can contain industrial by-products that can become waste. For example, LYTAG is a commercially available sintered aggregate containing finely divided fuel ash (“PFA”) and is also referred to as fly ash. PFA is produced, for example, from the combustion of coal at a power plant.

  Natural aggregate used in construction is in great demand. However, aggregate resources are finite and the extraction and processing of that material is complicated by, for example, environmental issues, legal issues, availability, urban expansion and transportation costs. Waste generation by various industries is also increasing significantly and must be disposed of in an environmentally and legally acceptable manner. Typically, most of the generated waste is disposed of in landfills at great expense. Disposal of waste has been a major problem for many years due to the depletion of usable landfills, the difficulty of acquiring new locations, the potential for environmentally harmful effects, and the cost of landfills.

  If the waste can be processed and changed to produce practical synthetic aggregates for use in concrete and other applications, both the waste problem and the depletion of natural aggregate resources will be solved. .

Aggregates can be light weight or normal weight. Lightweight aggregates ( "LWA"), as is defined in ASTM Standard C330, with a loose packing bulk density dry than the particle density or 1.1 g / cm ³ less than 2.0g / c ^{m 3.} For example, normal weight aggregate from gravel, sand and crushed stone has a bulk specific gravity (both dryer-dried and surface-dried) of about 2.4 to about 2.9 and a bulk density of about 1.7 g / cm ³ or less. . A high quality LWA has a strong, uniform structural strength but a low density porous sintered ceramic core and a dense, continuous and relatively impermeable surface layer to prevent water absorption. They are physically stable, durable and environmentally inert. When used in concrete, LWA has sufficient crushing strength and fragmentation resistance so that the resulting concrete has a strength of over 10 MPa and a range of about 1.5 g / cm ³ to about 2.0 g / cm ³ . Must have a dry density. Relatively low density LWA can also be manufactured. Concrete containing LWA (“LWA concrete”) can also have a density as low as about 0.3 g / cm ³ .

  Synthetic lightweight aggregates (“LWA”) have received much attention due to their considerable effectiveness in relation to use in structural applications. Concrete containing LWA ("LWA concrete") can be 20-30% lighter than conventional concrete, but has comparable strength. Even when not as strong as conventional concrete, LWA concrete has less structural dead load, which can lead to longer use, reduced cross-section and reduced reinforcement in the structure. The relatively low weight of LWA concrete facilitates handling and reduces transportation, equipment and labor costs. With LWA concrete, insulation, freezing and thawing performance, fire resistance and volume reduction can also be improved.

  Sewage sludge produced by biological wastewater treatment plants is an important waste in terms of volume and heavy metal content. Sewage sludge contains precipitated solids that are deposited during various processing stages in the factory, such as primary or secondary precipitation, aerobic digestion or anaerobic digestion and other processes, and then separated from the liquid stream. The composition and characteristics of sewage sludge can also vary depending on the wastewater treatment process used and the sewage sludge treatment process. Sewage sludge may be untreated, digested, or dehydrated. Sewage sludge contains a significant amount of organic material and may contain high concentrations of heavy metals and pathogens. Sewage sludge is generally disposed of by the formation of inert ash by incineration, which is disposed of, for example, by lagooning, landfill, land application as fertilizer or soil conditioning, and ocean dumping. Unwanted contamination can occur when sewage sludge is untreated and applied to land or disposed of in landfills.

  The reuse and disposal of sewage sludge creates non-negligible economic and environmental problems. The presence of heavy metals and pathogens in waste that can leach from landfills poses a threat to adjacent land and water supply facilities. The use of landfills is becoming increasingly difficult. Furthermore, the presence of large amounts of water in the sewage sludge that increases the weight of the waste increases transportation and disposal costs.

  Another significant waste produced is the ash stream resulting from municipal solid waste (“MSW”) incineration. Disposal of MSW ash residue to landfill is only 1 / 10th of the original waste volume, but the management is problematic because of the significant amount of solid residue, most of which Currently it is landfilled. Incinerator bottom ash ("IBA") is the major ash stream that accounts for about 75-80% of the total weight of MSW incinerator residue, and is a slag, glass, ceramic, ferrous and non-ferrous metal, mineral, other It is a heterogeneous mixture of incombustibles and unburned organics. IBA is currently used as is (without heat treatment) in the construction of embankments, paved roadbeds and road auxiliary roadbeds, for soil stabilization, in bricks, blocks and paving stones, and as a filler for specific applications. The Although considered a relatively inert waste, heavy metal leaching can occur in these applications.

  MSW incineration also produces particulate residue in the form of dust that is floating in the combustion gas or collected by the exhaust control device, which is referred to as air pollution control ("APC") residue. These include fly ash, lime, carbon and residues recovered with pollution control systems. Incinerator filter dust (“IFD”) is APC residue collected in a baghouse filter that occurs at a rate of 25-30 kg per 1000 kg of incineration waste, and fly ash optionally contains IFD, combined with the entire ash stream It accounts for about 10% to 15% of the amount. MSW incinerator fly ash ("IFA") is classified as a toxic and hazardous residue in most European countries because it contains high concentrations of hazardous materials such as heavy metals, dioxins, sulfur compounds and chlorine compounds . Therefore, it can only be disposed of in a special landfill, which is expensive and not environmentally safe.

A considerable volume of residue is also generated by mining of minerals, ores and stones. Typical mining operations include extraction, beneficiation, blasting, crushing, cleaning, sieving, cutting (stone) and stockpiling. These operations produce wastes such as pulverized products, powders, mud residues and waste water of various sizes that require disposal. For example, marble and granite waste from cutting ornamental stones also contain a large amount of waste mud, which is discarded into rivers and swamps. Granite cutting and granite cutting machines also produce large amounts of powder and mud waste residues. The term “mining waste” is used herein to refer to waste generated during these operations. Mining waste must be treated and disposed of in swamps and landfills to prevent environmental pollution. Other mining wastes include, for example, limestone and dolomite tailings.

  Power plants also produce large amounts of ash residue in the form of fines, also referred to as pulverized fuel ash (“PFA”) and crude fractions, also referred to as furnace bottom ash (“FBA”). The relatively heavy ash accounts for 20-30% of the total coal ash generated and falls to the bottom of the furnace. FBA is currently used in its raw form as aggregate in lightweight concrete, Portland cement manufacturing and other asphalt or road infrastructure applications.

Other wastes that occur at high rates include cement kiln dust (“CKD”) and blast furnace slag (“BFS”) . CKD is a by-product of a fine powder cement manufacturing operation that is captured by an air pollution prevention dust recovery system in a manufacturing plant. In the United States, approximately 14.2 million tons of CKD are generated each year, and approximately 64% of the total CKD generated is reused in cement plants. BFS is a non-metallic product of iron production and processing in a blast furnace. It is estimated that approximately 15.5 million tonnes of BFS occur annually in the United States, most of which is used in cement production as aggregate or insulating material.

SUMMARY OF THE INVENTION Because of the economic burden and environmental hazards associated with waste disposal, it is advantageous to develop separate technologies that turn waste into safe and profitable products. Production of construction and building materials such as synthetic aggregates by reusing waste is effective because a large amount of waste can be used to reduce the demand for non-renewable raw materials for material aggregates. This is considered a good option.

  According to one embodiment of the present invention, an aggregate manufacturing method is disclosed that includes mixing sewage sludge from a wastewater treatment facility with non-coal burned ash silicon aluminum waste. The method further includes the steps of agglomerating the mixture to form an aggregate and firing the aggregate to form an aggregate. The waste may include municipal solid waste incinerator residue, waste glass, blast furnace slag, kiln dust and / or mining waste. Municipal solid waste incinerator residues may include air pollution control residues and / or incinerator bottom ash. Air pollution control residues include incinerator fly ash and / or incinerator filter dust. Kiln dust includes cement kiln dust. Mining waste includes granite cutting residue.

  In one example, the waste contains more calcium than sewage sludge. In this example, the waste includes incinerator filter dust, incinerator bottom ash, cement kiln dust, waste glass and / or blast furnace slag. Waste can contain more than 9% calcium and sewage sludge can contain less than 3% calcium. The resulting aggregate can contain less than about 10% calcium by dry weight. The method can include mixing about 99% to about 60% of the sewage sludge by dry weight of the mixture with about 1% to about 40% of the waste by dry weight of the mixture. Preferably, the method includes mixing about 80% to about 90% sewage sludge with about 10% to about 20% of the waste by dry weight of the mixture.

  In another example, the waste contains less calcium than sewage sludge. In this example, the waste can include furnace bottom ash, granite cutting residue and / or waste glass. The waste can contain less than about 10% calcium and the sewage sludge can contain more than about 10% calcium. The aggregate can include less than about 10% calcium. The method can include mixing about 5% to about 95% sewage sludge by dry weight of the mixture with about 95% to about 5% of the waste by dry weight of the mixture. Preferably, the method includes mixing about 30% to about 70% sewage sludge by dry weight of the mixture with about 70% to about 30% of the waste by dry weight of the mixture. More preferably, the method includes mixing about 30% to about 50% sewage sludge by dry weight of the mixture with about 70% to about 50% of the waste by dry weight of the mixture.

  The method can further include grinding the waste prior to mixing. Preferably, the pulverization is wet pulverization. The mixture of sewage sludge and waste is preferably pulverized and then agglomerated. Preferably the agglomeration comprises pelleting. At least a portion of the moisture can be removed from the wet milled waste and at least a portion of the moisture can be used during pelletization and / or quenching of the calcined agglomerates. The resulting aggregate can have a diameter of about 3 mm to about 40 mm.

  The agglomerates can be coated with an inorganic powder. Aggregation can be performed after the plastic binder is mixed with sewage sludge and waste. The plastic binder may include clay. The clay binder may include about 5% to about 20% by dry weight of the mixture.

  The firing treatment of the aggregate can be performed with a rotary kiln. The resulting aggregate can be, for example, a lightweight aggregate or a normal weight aggregate. Aggregates can be vitrified. Certain characteristics of the aggregate can be controlled based at least in part on the ratio of sewage sludge to waste and the firing temperature. The specific characteristics may include aggregate density, water absorption and / or strength.

  According to another embodiment of the present invention, producing a mixture comprising sewage sludge and non-coal combustion ash, silicon aluminum waste from a wastewater treatment facility, agglomerating the mixture to form an aggregate, and Disclosed is a method for producing a sintered lightweight aggregate comprising the step of sintering the agglomerates. The waste may include incinerator fly ash, incinerator filter dust, incinerator bottom ash, furnace bottom ash, waste glass, blast furnace slag, cement kiln dust and / or granite cutting residue.

  According to another embodiment of the present invention, a sintered lightweight aggregate comprising sewage sludge from a wastewater treatment facility and non-coal burned ash, silicon aluminum waste is disclosed. The mixture of sewage sludge and waste is sintered at a temperature that forms a sintered lightweight aggregate. The waste can include, for example, incinerator fly ash, incinerator filter dust, incinerator bottom ash, waste glass, blast furnace slag, cement kiln dust, and / or granite cutting residue. The lightweight sintered aggregate can include about 2% calcium to about 10% calcium. Preferably, the lightweight sintered aggregate can comprise about 3% to about 6% calcium. The lightweight sintered aggregate can be chemically inert.

  According to another embodiment of the present invention, the calcined aggregate includes sewage sludge and non-coal combustion ash, silicon aluminum waste from a wastewater treatment facility. The aggregate can be sintered or vitrified. The aggregate can be a normal weight or a lightweight aggregate.

  According to another embodiment, the calcined aggregate consists of sewage sludge. Sewage sludge can contain less than 40 wt% organic material.

  According to another embodiment, mixing sewage sludge from a wastewater treatment facility and furnace bottom ash (“FBA”) from a coal combustion facility, aggregating the mixture to form an aggregate, the aggregate A method for producing an aggregate is disclosed, which includes a step of firing to form an aggregate. According to another embodiment, a calcined aggregate comprising sewage sludge from a wastewater treatment facility and furnace bottom ash from a coal combustion facility is disclosed.

  According to another embodiment of the present invention, the step of reducing the water content of sewage sludge from a wastewater treatment facility to a level capable of coagulation, the step of coagulating the sewage sludge, and the aggregate by firing the aggregate A method of manufacturing an aggregate is disclosed, including the step of forming a.

  According to another embodiment, pulverizing at least one of clay or shale, removing at least a portion of moisture in sewage sludge from a wastewater treatment facility, and treating the sewage sludge with the clay or shale. Disclosed is a method of manufacturing an aggregate that includes mixing. The mixture is pelletized, and the resulting pellet is fired in a rotary kiln to form an aggregate. The mixture of the sewage sludge and the clay or shale can be wet-ground.

  According to another embodiment, a method for producing aggregate is disclosed that includes mixing sewage sludge from a wastewater treatment facility with slate, lime, limestone, dolomite and / or gypsum. The mixture is aggregated to form an aggregate. Next, the aggregate is fired to form an aggregate. One or more natural materials such as slate, lime, limestone, dolomite or gypsum can be processed and then mixed with sewage sludge.

  According to another embodiment, a calcined aggregate comprising sewage sludge from a wastewater treatment facility and slate, lime, limestone, dolomite and / or gypsum is disclosed.

  According to another embodiment, incineration of a first material that can include ground fuel ash from coal combustion, coal, clay, shale, slate, granite cutting residue, waste glass and / or furnace bottom ash Disclosed is a method of manufacturing an aggregate that includes mixing with a second material that can include furnace fly ash, cement kiln dust, incinerator filter dust, blast furnace slag, limestone, gypsum, dolomite and / or waste glass. Is done. The mixture is aggregated to form an aggregate, and the aggregate is fired to form an aggregate. The first material can include less than about 3% calcium by dry weight, and the second material can include greater than about 9% calcium.

  According to another embodiment of the present invention, mixing sewage sludge from a wastewater treatment facility and incinerator residue from a municipal solid waste incinerator, agglomerating the mixture to form an aggregate, and Disclosed is a method for producing an aggregate comprising the step of firing the aggregate to form an aggregate. The incinerator residue may include incinerator bottom ash, incinerator fly ash and / or incinerator filter dust.

  According to another embodiment of the present invention, a first material comprising a first material that is pulverized fuel ash or clay from coal combustion is treated with slate, lime, limestone, dolomite, gypsum, blast furnace slag, incinerator fly. Disclosed is a method of manufacturing an aggregate that includes mixing with one or more second materials that are ash, incinerator filter dust or cement kiln dust. The mixture is agglomerated and the aggregate is fired to form an aggregate.

  According to another embodiment, the first material and slate, lime, limestone, dolomite, gypsum, blast furnace slag, incinerator fly ash, incinerator filter, which can be ground fuel ash and / or clay from coal combustion Disclosed is a calcined aggregate comprising a second material that can be dust and / or cement kiln dust.

  The behavior of a material when heated is mainly determined by its composition, particle size and mineral composition. A good ratio between the flowable material and the refractory mineral is required to control densification at the firing temperature during the production of sintered and vitrified products with the desired density, water absorption, etc. . Refractory minerals such as silica and alumina generally have a high melting point. Due to the presence of flowable minerals such as the alkaline earth metals calcium and magnesium and the alkali metals sodium and potassium present in the oxide, carbonate or sulfate material form, silica and alumina and other refractories in the material. The melting point of minerals decreases. When the proportion of the fluid mineral in the material is high, the proportion of silicon, which is a glass network forming element, is lowered accordingly. Flowable minerals promote sintering and melting of the components in the mixture at the lowest eutectic temperature. Furthermore, flowable minerals with low viscosity and high mobility are useful for the formation of sintered or vitrified products, depending on the temperature involved, by liquid phase sintering.

Sewage sludge is a heterogeneous waste, and its composition can vary greatly depending on the characteristics of the wastewater inflows that primarily enter a particular wastewater treatment plant and the treatment processes used in the wastewater and sludge treatment processes. Sewage sludge is used in some embodiments of the present invention as an initial raw material for the production of calcined aggregates. Aggregate production processing according to embodiments of the present invention was performed on sewage sludge from two different treatment plants. A sewage sludge sample (sample X, described in Example 1 below) from one wastewater treatment plant was partially composed of about 16.02% silica (SiO ₂ ), 6.83% alumina (Al ₂ O ₃ ) and 20.28% calcium oxide (CaO). Sample Y, also described in Example 1 below, is partially about 31.24% silica (SiO ₂ ), 6.22% alumina (Al ₂ O ₃ ), and 12.12% calcium oxide ( CaO). These samples contain a large amount of alkaline earth metal calcium, which lowers the melting point of the remaining compounds in the sludge. Accordingly, densification occurs at a temperature lower than the melting point of silica and alumina, which are refractory minerals. Furthermore, the calcium component acts as a fluxing agent useful for the formation of sintered or vitrified products by liquid phase sintering. Whether the mixture is sintered or vitrified depends on the firing temperature and the composition of the mixture. The flowable mineral melts to form a low viscosity, high mobility liquid that absorbs and dissolves the remaining refractory mineral very quickly. Furthermore, the mobility of the silicate melt is enhanced by the presence of volatile components in the sludge. This liquid formation causes the densification acceleration behavior of this kind of sewage sludge when the firing temperature is increased.

The sewage sludge sample from the second wastewater treatment facility had these fluxes at low concentrations. Sample Z, described below in Example 4, is composed of 3.20% calcium oxide (CaO), 3.80% aluminum oxide (Al ₂ O ₃ ) and 39.50% silicon oxide (SiO ₂ ). It is an example of the low calcium sewage sludge which has a partial composition. Due to the relatively high concentration of refractory minerals such as silica, densification occurred over a wider temperature range at relatively high temperatures.

  According to one embodiment of the present invention, a calcined aggregate containing 100% sewage sludge and a method for producing such aggregate are disclosed. It was found that by controlling the composition of the sewage sludge by mixing the sewage sludge with additives and changing its behavior during the firing treatment, the control of aggregate production can be better. Thus, according to other embodiments, certain waste and natural additive materials are mixed with sewage sludge. The selection of the additional material depends on the composition of the sewage sludge. Preferably, the material is selected such that the resulting aggregate has a calcium content of about 2% to about 10%. More preferably, the calcium content is about 2% to about 6%.

In one example embodiment, a sewage sludge having a high calcium content, such as, for example, a calcium content greater than 10%, is converted to a low calcium silicon aluminum material (“LCSAM”) having a calcium content less than the sewage sludge content. To change the composition of the sewage sludge and hence its densification behavior during the firing process. For example, high calcium picking Lee-containing aluminum sewage sludge may have a calcium content greater than 10%, LCSAM may have a calcium content of less than about 10%. LCSAM is also referred to as a Group A additive or material in this embodiment. LCSAM includes waste such as waste glass (“WG”), furnace bottom ash (“FBA”) and certain mining waste such as granite cutting residue (“GSR”). LCSAM also includes natural material slate.

  The addition of LCSAM to high calcium sewage sludge provides (1) material densification and / or (2) bone by providing a relatively low mobility and relatively high viscosity melt from LCSAM. It has been observed that the temperature range during initial softening, sintering and melting of the material is increased. This has been found to provide better control of the aggregate production process compared to processing 100% high calcium sewage sludge.

In another example embodiment, sewage sludge having a low calcium content is mixed with a high calcium silicon aluminum material (“HCSAM”) (referred to in this embodiment as a Group B additive or material). Low calcium sewage sludge can have a calcium content of less than 3% and HCSAM can have a calcium content of greater than 9%. The HCSAM in this embodiment includes, for example, (1) waste: municipal solid waste (“MSW”) incineration residue, cement kiln dust (“CKD”) and blast furnace slag; and (2) natural materials: limestone, There are plaster and dolomite. Municipal solid waste (“MSW”) incineration residues include air pollution control residues and incinerator bottom ash (“IBA”). Air pollution control residues include incinerator fly ash and incinerator filter dust.

  Addition of HCSAM to low calcium sewage sludge (1) narrows the temperature range in which the sewage sludge-containing aggregate can be fired; (2) provides a liquid melt that accelerates sintering and / or vitrification; And (3) it has been recognized that it is possible to produce aggregates with specific characteristics (eg density) depending on temperature and composition.

  Waste glass contains non-negligible amounts of flux components such as calcium and sodium (9% and 12% by weight, respectively) and refractory minerals such as silica (71.7% by weight). Thus, waste glass can be an additive for both Group A and Group B, depending on the composition of the sewage sludge. That is, waste glass can reduce the calcium content of high calcium sewage sludge or increase the calcium content of low calcium sewage sludge.

  In another example of one embodiment, synthetic aggregate is produced from a mixture of at least one LCSAM and at least one HCSAM. In one example, LCSAM contains less than 3% calcium and HCSAM contains more than 10% calcium. It has been observed that a mixture of LCSAM and HCSAM provides a good ratio between refractory and flowable minerals, allowing for control of the firing process. LCSAMs in this embodiment include, for example, waste: pulverized fuel ash (“PFA”) from coal combustion facilities and other LCSAMs described above, as well as clay, shale and slate. The clay can be, for example, bentonite and / or kaolin. The HCSAM in this embodiment is the same as described above except that the MSW incinerator bottom ash is not included. Addition of HCSAM to LCSAM gives the mixture the desired composition with an appropriate ratio of flux to refractory minerals to better control the production process to produce aggregates of the desired properties It is intended.

  In another embodiment, a range of density, porosity and water absorption of the synthetic aggregate can be obtained by controlling the ratio of sewage sludge to the second material / additive and the firing temperature.

FIG. 1 shows sintering temperatures for aggregates containing sewage sludge (Sample X in Example 2 below) and aggregates containing a mixture of sewage sludge and granite cutting residue, ranging from about 920 ° C. to about 1150 ° C. It is a graph of density (g / cm < ³ >) with respect to (degreeC). Curve A, corresponding to an aggregate containing 100% SS, shows a density from a low value of about 1.2 g / cm ³ to a maximum density of about 2.5 g / cm ³ as the temperature increases from about 920 ° C. to about 960 ° C. It shows that it rises. As the temperature increases from 960 ° C. to 980 ° C., the density decreases from a maximum density of about 2.5 g / cm ³ to 1.7 g / cm ³ . Aggregates with a density of 2.0 g / cm ³ or less are called lightweight aggregates, and aggregates with a density higher than 2.0 g / cm ³ are usually called heavy aggregates.

  When the product is sintered, the flux in the sewage sludge melts to form a liquid phase, which fills the pores between the particles in the sewage sludge by capillary action, so the temperature from 920 ° C. to 960 ° C. The density increases with the rise. As the holes fill, the density increases and the sample volume decreases. Furthermore, relatively small particles in the liquid phase diffuse towards larger particles. The molten material forms a rigid, glassy amorphous skeleton or matrix upon curing. As the processing temperature increases, more of the compound in the sewage sludge melts and virtually all the pores disappear, forming a more glassy crystalline solid matrix. At the maximum densification temperature, almost all pores are filled and the product vitrifies.

  As the temperature rises further, the sample melts and expands, and as the temperature increases from 960 ° C. to 980 ° C., the density decreases rapidly. Expansion is caused by gas uptake into the molten liquid phase, which is caused by vaporization of some components of the sample. The trapped gas forms a hole.

As shown in FIG. 1, sewage sludge is rapidly sintered in a very narrow temperature range. For example, to produce a sintered lightweight aggregate containing 100% sewage sludge having a density in the range of about 1.4 g / cm ³ to about 1.8 g / cm ³ , the sintering temperature is 930-940 ° C. It must be within range and its width is only 10 ° C. Furthermore, variations in the composition of a given sample of sewage sludge can cause large variations in the behavior of the sewage sludge sample during heating. Thus, the relationship between temperature and density for various sewage sludge samples can vary over a wide range. As a result, it is very difficult to obtain a sewage sludge final product having desired characteristics such as density, porosity, and water absorption. The fact that the densification behavior of sewage sludge having a composition similar to that of this sample (high calcium) cannot be controlled by temperature is a serious obstacle to producing aggregates with the characteristics required for mass production. Conceivable.

The low calcium silicon aluminum material (LCSAM) used in embodiments of the present invention contains more silica and less calcium compared to sewage sludge. As noted above, the sewage sludge sample (Sample X) used in Examples 1 and 2 below is about 16.02% silica (SiO ₂ ), 6.83% alumina (Al ₂ O ₃ ) and 20 Contained 28% calcium oxide (CaO). Natural LCSAM clays (eg bentonite and kaolin), shale and slate are about 48% to 58% silica (SiO ₂ ), about 18% to about 29% aluminum (Al ₂ O ₃ ) and less than about 3% oxidation. Contains calcium (CaO). An example of a mining waste that can be used in certain embodiments of the present invention, granite cutting residue (“GSR”) is about 65% silica (SiO ₂ ), about 15% alumina (Al ₂ O _3). ) And about 2.6% calcium oxide (CaO). The waste glass contains about 72% silica (SiO ₂ ), about 2% alumina (Al ₂ O ₃ ) and about 9% calcium oxide (CaO). Since waste glass further contains about 12% sodium oxide (Na ₂ O), which is also a flux compound, it can be used to increase or reduce the amount of flux in sewage sludge. Furnace bottom ash (“FBA”) having the same composition as ground fuel ash from coal combustion (“PFA”) is about 52% silica (SiO ₂ ), about 26% alumina (Al ₂ O ₃ ) and about Contains 2% calcium oxide (CaO). Other components of these LCSAMs are listed in the examples below.

As shown in FIG. 1, for example, a 60% / 40% sewage sludge (“SS”) / granite cutting residue (“GSR”) mixture with a density of about 1.5 g / cm ³ to about 1.8 g / cm To produce a sintered lightweight aggregate of ³ , the sintering temperature can be in the range of about 30 ° C. (about 1010 ° C. to about 1040 ° C.). For 40% / 60% SS / GSR mixtures, similar densities can be obtained at temperatures in the range of about 1010 ° C to about 1075 ° C and 65 ° C. Furthermore, when the GSR concentration is increased to 60%, the sintering is delayed and reaches the maximum density at about 1110 ° C (in contrast, 960 ° C for 100% SS and 60% / 40% SS / GSR for 100% SS). 1060 ° C.). Expected to be a lightweight aggregate GSR is having a density of over a wide temperature range even more increasing the 40% / 60% SS / GSR mixture to 80% to about 1.5 g / cm ³ ~ about 1.8 g / cm ³ Is done. The relatively wide temperature range facilitates the production of aggregates having the desired density and other characteristics even if the SS composition varies. FIG. 1 is based on the results of Example 2 below.

FIG. 2 shows sintering temperatures for aggregates comprising sewage sludge (sample Z in Example 4 below) and aggregates comprising a mixture of sewage sludge and cement kiln dust, ranging from about 980 ° C. to about 1110 ° C. is a graph of density (g / cm ³⁾ with respect ° C.). Curve B, corresponding to 100% sewage sludge, increases in density from a low value of about 1.9 g / cm ³ to a maximum density of about 2.4 g / cm ³ as the temperature increases from about 980 ° C. to about 1060 ° C. It is shown that. As the temperature increases from 1060 ° C. to 1110 ° C., the density decreases from a maximum density of 2.4 g / cm ³ to 2.0 g / cm ³ . Aggregates having a density greater than 2.0 g / cm ³ are usually heavy aggregates.

As shown in FIG. 2, in sewage sludge, since the amount of refractory components in the sewage sludge is large, densification is delayed and the temperature interval between initial material softening, sintering and melting is widened. In this example, the examined temperatures, usually weight aggregate having a density of 2.0g ^/ cm ³ ~2.4g ^/ cm 3 was produced in a wide temperature range of 110 ℃ (1000~1110 ℃). To accelerate the densification behavior of materials to produce both light and normal weight aggregates within a temperature range that provides predictability and production control, high calcium silicon aluminum, Group B materials (“HCSAM”) ) To the sewage sludge. In this example, the HCSAM is cement kiln dust (“CKD”). Since CKD contains a significant amount of CaO (63% by weight), only a small amount of CKD is required to obtain an acceleration effect. The sewage sludge by adding 5% of CKD, when calcined at the same temperature range as 100% sewage sludge mixture, lightweight aggregate having a density of about 1.7 g / cm ³ ~ about 2.4 g / cm ³ The material is manufactured. When 10% CKD is added to sewage sludge, a light aggregate having a low density of 1.4 g / cm ^{3 and} a density of about 2.4 g / cm ³ or less at a firing temperature of 940 ° C. to 1060 ° C. Heavy aggregate is produced. Adding more CKD is not desirable because it further accelerates the densification of the mixture, which can be a hindrance to controlling the production process in a predictable manner in mass aggregate production.

  In a method according to an embodiment of the present invention, a predetermined amount of sewage sludge and a second material that can be LCSAM or HCSAM depending on the composition of the sewage sludge are mixed, the mixture is agglomerated, Aggregates are formed by firing at a temperature. As mentioned above, LCSAM has less calcium-containing components than the first sewage sludge, and HCSAM has more calcium than sewage sludge. The temperature is based, at least in part, on the ratio of sewage sludge to silicon aluminum material (“SAM”) as well as the desired density and water absorption of the aggregate and / or data based on data such as those shown graphically in FIGS. Or it can be selected based on other characteristics such as strength. A temperature that causes sintering is preferred. Preferably, the mixture is agglomerated and then sintered to form an aggregate having a desired size and shape, thereby forming a sintered aggregate. Pelletization is a preferred agglomeration method. The sewage sludge can be dried and then mixed with the second material. Alternatively, aggregation can be made possible by adding sewage sludge in a wet form having a desired water content.

  FIG. 3 shows LCSAM particles 12 such as clay, shale, slate, granite cutting residue, waste glass and furnace bottom ash or HCSAM particles 12 such as cement kiln dust, blast furnace slag, limestone, gypsum and dolomite, and sewage sludge particles. 14 is an example of an aggregate 10 containing 14. A hole 16 is also shown. Aggregate 10 may be fired, eg, sintered, to form an aggregate in accordance with one embodiment of the present invention. During the firing process, the melting point below the processing temperature of the fluxing compounds such as calcium oxide, sodium oxide, potassium oxide and magnesium oxide and the first particles of the sewage sludge 14 and the high or low silicon aluminum material (“SAM”) particles 12 Other compounds it has melted and flow into the holes 16. If the SAM particles 12 are waste glass that is an amorphous solid, densification occurs due to melting of the softened glass particles by viscous sintering at a temperature significantly lower than the melting point of the other crystalline SAM particles.

  FIG. 4 is a schematic cross-sectional view of an example aggregate 20 obtained from sintering aggregate 10 according to one embodiment of the present invention. Aggregate 20 includes a mixture of sewage sludge and SAM. The agglomerates are sintered at a temperature that depends on the ratio of sewage sludge to SAM and the desired density and / or other characteristics. Sintered aggregate 20 includes a plurality of particles 22 joined together by a partially glassy and partially crystallized matrix 24 resulting from melting and / or crystallization of the components. The particles 22 can include silica, alumina, and other minerals having a melting point above the processing temperature. The particles 22 crystallize completely or partially during sintering to provide another bond between the particles 22. Aggregate 20 preferably has a dense, continuous, relatively impermeable surface layer 26 obtained by coating the aggregate 10 with an inorganic material as further described below. There are also internal holes 28, which can be microscopic and channel-like, small surface holes 28a. Since the surface hole is connected to the internal hole, the aggregate 20 may be able to absorb water. Water absorption is an indicator of pore volume and connectivity.

  FIG. 5 is a schematic cross-sectional view of an example of vitrified aggregate 30 according to another embodiment of the present invention. The vitrified aggregate 30 has fewer particles 22 and a larger matrix 24 than the sintered aggregate of FIG. Vitrification results from the calcination of the aggregate 10 above the maximum densification temperature for a specific ratio of sewage sludge to SAM, where most of the aggregate components melt.

A highly porous lightweight aggregate with a low density of about 1.2 g / cm ³ , a water absorption of over 40% and a very low strength, and a very strong and good density of 2.0 g / cm ³ or less Sintered lightweight aggregate can be manufactured according to embodiments of the present invention. Density of less than about 2.0 g / cm ³ higher than about 2.6 g / cm ^3, water absorption is also normal weight aggregate close to zero may be prepared by embodiments of the present invention. Aggregate production by sewage sludge and SAM and among certain waste SAMs provides an advantageous reuse application.

  FIG. 6 is an example of an aggregate manufacturing method 100 according to an embodiment of the present invention. The sewage sludge is first dried at step 105. Sludge can be dried, for example, with a dryer at 110 ° C. for 24 hours. If the moisture content of the untreated sludge is very high, excess water is removed, for example by filtration, gravity sedimentation, flocculent sedimentation or sedimentation, and then dried in a dryer. Typically, a dried sewage sludge mass is formed. It may be necessary to reduce the size of the mass. A fine powder suitable for subsequent processing is preferably produced at step 110, for example by dry grinding or grinding, or by using a pestle and mortar. In mass production, the dried solid cake can be pulverized into powder, for example, with a hammer mill. The ground sewage sludge powder is separated at step 115 using, for example, a sieve to remove large particles. Coarse particles such as stones, rocks or metals present in the sewage sludge are also preferably removed and subjected to further processing. Separation can be performed by mechanically shaking the sewage sludge powder on, for example, an ASTM standard stainless mesh screen having an opening of 150 microns or 80 microns. Sewage sludge having a particle size of less than 150 microns is further processed.

  A high surface area / volume ratio increases the diffusion of relatively small particles through the liquid phase of the small particles, resulting in better distribution of powder throughout the aggregate and better packing density. Powders with a good particle size distribution (less than about 710 microns) have advantageous characteristics.

  The sewage sludge can also be used in raw wet form, as long as the material has a suitable water content to allow further processing, for example according to steps 125-150 in FIG. . Excess water can be removed again by drying, filtration and / or other methods to achieve a suitable water content before mixing with the additive. In this case, steps 105-120 are not performed.

Next, in step 125, the ground sewage sludge powder from step 120 is mixed with a suitable SAM in powder form having a fine particle distribution. Mixing can be batch or continuous. If the SAM has a coarse particle size distribution, it can be preground with a hammer mill or ball mill, for example using dry or wet grinding techniques, and then added to the mixer along with the sludge powder. Any amount of high or low calcium SAM can be added to the low or high calcium sewage sludge, respectively, to enhance the firing performance. The preferred range of sewage sludge for SAM depends on whether the sewage sludge is high calcium sewage sludge or low calcium sewage sludge .

  Preferably, about 5% to about 95% high calcium sewage sludge is mixed with about 95% to about 5% LCSAM, BDWM at the dry weight of the mixture ("BDWM"). More preferably, about 30% to about 70% high calcium sewage sludge BDWM is mixed with about 70% to about 30% LCSAM, BDWM. In this range, the resulting aggregate has a calcium content of about 6% to about 15% by dry weight. More preferably, about 30% to about 50% high calcium sewage sludge BDWM is mixed with about 70% to about 50% LCSAM, BDWM. In this range, the resulting aggregate has a calcium content of about 6% to about 10% by dry weight. When the calcium content of the aggregate is about 2% to about 10%, the control of the densification behavior of the mixture becomes better, and it becomes possible to produce an aggregate having desired characteristics, and the calcium content is about 3 It is recognized that better control can be obtained when the content is from about% to about 6%.

  Preferably, about 99% to about 70% low calcium sewage sludge BDWM is mixed with about 1% to about 30% HCSAM, BDWM. More preferably, about 80% to about 90% low calcium sewage sludge BDWM is mixed with about 20% to about 10% HCSAM, BDWM. These ranges provide aggregate calcium content similar to that described above.

A plastic binder such as clay can be added to enhance the physical bonding of the individual particles with water during granulation, which is described in step 125. The term “plastic binder” refers to a binder material having a high plasticity index. A plastic index of at least 10 is preferred. The clay binder can comprise from about 5% to about 20% by dry weight of the mixture of SS , SAM and clay binder. The amount of binder used can depend on the type and characteristics of the sewage sludge and SAM, such as the plasticity of the individual components in the mixture.

After the powder is thoroughly mixed, at step 130, water is added to obtain a consistency suitable for agglomeration. The mixture preferably has a clay-like viscosity , for example. The amount of water added is related to the amount and type of additive in the mixture. For example, if the ratio of sewage sludge to clay is about 80% sewage sludge ("SS") / 20% clay, the amount of water required should be about 25% by weight of the total dry weight of the SS / clay mixture. Is allowed. When the proportion is 60% / 40%, it is recognized that the amount of water required is about 28% by weight. When the proportion is 20% / 80%, it is recognized that the amount of water required is about 32%. If the sewage sludge is used in wet form and the SS / SAM and optionally clay mixture has a suitable moisture content that allows further processing, it is not necessary to add water to the mixture.

  The resulting mixture is agglomerated in step 135. Agglomeration is a particle size enlargement technique that collects small fine particles such as dust or powder into larger lumps such as pellets. Preferably, the mixture is agglomerated by pelletization, in which case the fine particles dispersed in the gas or liquid are enlarged by rotation without using other external compression forces. For example, a pelletized rotating drum or disk can be used. The strength of the resulting pellets depends on the properties of the particles, the amount of moisture in the medium, and mechanical process parameters such as rotational speed and tilt angle of the rotating drum as is known in the art. An example of the use of a rotating drum is described in the examples below. The resulting pellets are approximately spherical or slightly angular and the color varies from light brown to dark brown depending on the carbon and iron content in the mixture. The diameter is, for example, in the range of about 3 mm to about 40 mm. As described above, FIG. 3 is an example of the pellet 10. Extrusion can be used instead of pelletization. Extrusion results in a brick-like material that can be crushed into smaller particles after curing. Alternatively, compression can be performed to obtain cylindrical aggregates such as tablets and other shapes.

The agglomerated mixture is appropriately surface coated and dried at step 140. The amount of inorganic material used can be small. The pellets can be coated with an inorganic material that does not melt at the sintering temperature. The pellets can be coated by dusting the dust or rotating the pellets in the dust. The use of the coating material depends on the characteristics of the sewage sludge and the additive selected. If the sewage sludge is high calcium sewage sludge, it is believed that the inorganic material can include, for example, granite cutting residue in the form of dust, clay, crushed shale and slate or LCSAM from group A such as furnace bottom ash It is done. If the sewage sludge is a low calcium sewage sludge, the inorganic materials include HCSAM from Group B such as cement kiln dust, incinerator fly ash, incinerator filter dust, limestone, gypsum and ground granular blast furnace slag ("GGBS"). Can be included.

  By coating the pellet surface with a thin layer of non-adhesive material, a coating is formed on the pellet surface, which reduces pellet clustering, increases pellet strength, and bone, for example as shown in FIG. A thin and dense outer coating is formed on the material. When adding a clay binder to the mixture, the clay improves internal bonding, so there is no need to coat the pellet surface to increase pellet integrity and form a coating. However, coating is an option. Drying can be performed with a drier at about 110 ° C., for example. In the baking treatment of the wet pellets in the kiln, since there is a possibility of cracking or explosion due to a rapid temperature change, drying is preferably performed.

  The coated and dried pellets are fired at step 145. The firing process is performed at a temperature of about 1000 ° C. to about 1350 ° C., for example, as described in more detail below, depending on the composition of the mixture and the desired properties of the aggregate. The firing treatment can be sintering that occurs at a temperature below the maximum densification temperature or vitrification that occurs at a temperature above the maximum densification. The firing treatment is preferably performed in a rotary kiln. Sintering creates an interparticle bond that increases the strength and density of previously loosely bonded particles. Vitrification increases strength at the maximum densification temperature. However, since vitrification proceeds at higher temperatures, as described above, density and strength are reduced due to the expansion of the glassy amorphous matrix.

  At step 150, the fired aggregate can be quenched in water. The pellets are cooled by rapid cooling and the melting is stopped. When the rapid cooling is performed, the obtained aggregate 20 has a matrix 24 having a higher amorphousness than that in the case of air cooling that can be recrystallized. It is known in the art that quenching improves the hardness, toughness and wear resistance of the fired aggregate. The water can be at room temperature (about 30 ° C.), for example.

  If firing and quenching are performed, the pellets can then be crushed and sorted to the desired aggregate size at step 155. Preferably, the coarse aggregate ranges from about 4.75 to about 19 mm. For example, smaller aggregates can be used as fine aggregates in concrete.

  Due to the shrinkage of the pellets during the firing process, if the size of the pellets is in the range of about 3 mm to about 40 mm, for example, the size of the fired aggregate can be in the range of about 2 mm to about 30 mm. A suitable size range for the screened aggregate can be about 4 mm to about 8 mm that can be used for filtration applications, as well as about 12 mm to about 19 mm that can be used for concrete. For example, smaller aggregates (down to about 2 mm) can be used as fine aggregates in concrete.

  As a result of the firing process according to embodiments of the present invention, aggregates are believed to be chemically inert to most substances under normal environmental conditions.

  FIG. 7 is an example of a plurality of sintered aggregates made according to an embodiment of the present invention from a mixture comprising 80% / 20% SS / bentonite fired at 990 ° C.

  FIG. 8 shows an example of an aggregate manufacturing method 200 according to an embodiment of the present invention, in which a specific SAM having a coarse particle distribution is wet-ground and then mixed with sewage sludge. Additives used in the present invention having such a distribution include IBA, FBA and waste glass.

  In step 205, IBA is added to the ball mill barrel and in step 210 it is ground with water. Grinding is performed to reduce the IBA particle size distribution to a fine distribution and improve the firing process. The high surface area / volume ratio increases the diffusion of small particles through the liquid phase into relatively large particles, and the powder is better distributed throughout the aggregate, resulting in better packing density. Powders having a size distribution have advantageous characteristics. The resulting particles preferably have an average particle size of, for example, about 45 microns or less. Wet grinding is preferred because it has been found that a more uniform particle size distribution can be obtained. Furthermore, liquids used in wet milling processes have a tendency to break up aggregates and reduce powder particle welding. Alternatively, IBA can be dry pulverized, for example, with a hammer mill. Although the method 200 of FIG. 8 is described with respect to the use of IBA, it is clear that if FBA or waste glass is used, they are also preferably ground.

  IBA can be wet pulverized, for example, in a sealed cylindrical container, and is capable of breaking particles suspended in the medium with a pulverized spherical medium such as a wet mill ball in a liquid medium such as water or alcohol. Will be added. Motion can be applied to the wet ball mill by rolling, vibrating, orbiting and / or stirring. The most important variables controlling the powder particle size distribution are grinding speed (rpm), grinding time, grinding media amount, raw material initial particle size and desired product diameter. To obtain the most efficient results, the mill must be at least half filled with grinding media. The grinding media can be, for example, high density aluminum spheres and can have a total weight of about 4 times the solids. For optimal grinding, a small grinding media is recommended. When using aluminum or steel balls, the preferred particle size is in the range of 1/2 to 5/8 inch. Preferably, about twice as much liquid as the solid is added. The grinding can be performed, for example, for about 8 hours.

  In step 215, the wet milled IBA is separated, for example, with a sieve to remove large particles. If the particles are too large, uniform pellets are not formed. Separation can be performed in multiple stages. For example, the IBA can be mechanically shaken on an ASTM standard stainless mesh screen having an opening of, for example, 355 microns or 150 microns. Further processing of IBA having a particle size of less than 150 microns. Fractions over 150 microns can be separated into different types of materials, which can be reused as SAM additives and waste glass.

  The resulting ground slurry from step 220 is dewatered in step 225. Preferably, all free water is removed. The removed water is referred to as waste water and can be used in step 265 as described further below. Water can be removed, for example, with a filter press or other filtration device. At step 230, dehydration forms a solid wet cake residue.

  In step 235, the cake is dried and ground. This stage turns the cake into a powder. The cake can be dried with a dryer at 110 ° C., for example. The powder can be pulverized, for example, with a mortar and pestle. In mass production, the dried solid cake can be ground into a powder, for example with a bladed mixer or dry hammer mill, so the dry ground IBA solid cake is ground at the same time and continuously with the raw additive, also in powder form Can be mixed.

  Prior to mixing the ground IBA with sewage sludge, the sludge is dried at step 240. The sludge can be dried for 24 hours with a drier at 110 ° C., for example. The produced solid cake is pulverized in step 245 to a powder. The powder can be produced, for example, by dry grinding or crushing, or using a pestle and mortar. In step 250, the sludge powder is passed through a 150 or 80 micron sieve to remove coarse particles. At step 260, the sub-150 micron fraction of step 255 is thoroughly mixed with the milled IBA powder. Water is added to the mixture and then the wet clay mixture is pelletized at step 265. The water can be part or all of the waste water obtained from the dehydration stage 225 described above. Steps 265 to 285 correspond to steps 130 to 155 in FIG. Alternatively, sewage sludge can be mixed with IBA in a wet state. However, an appropriate water content is necessary so that no further water needs to be added in the granulation of the mixture. In this case, steps 240-255 are not necessary.

  When wet slurry of IBA and sewage sludge together in a ball mill to obtain a slurry, another process can be performed. The ground slurry is then passed through a series of sieves and dewatered with a filtration device to form a viscosity-like solid cake. The solid cake is then dried at 110 ° C. and pulverized to a fine powder, which is further pelletized in the presence of water and fired to form aggregates. The milled slurry formed from wet milling of both materials can be dewatered to the required water content to allow direct pelletization of the mixture. The formed pellets are dried at about 110 ° C. and then subjected to a kiln firing stage.

  The following experiment was conducted.

Example 1
In this example, a synthetic aggregate containing sewage sludge (“SS”) and waste glass (“WG”) was produced. The average chemical composition (major oxide) of the three different SS samples used in this example is shown in Table A below. Table B below shows the minor and minor constituents present in these three samples. Sample X and Sample Y were obtained from the same factory with a period of about 6 months, and Sample Z was obtained from the second factory. Sample X has a calcium oxide content of 20.28% by weight; Sample Y has a calcium oxide content of 12.12% by weight; Sample Z has a calcium oxide content of 3.20% by weight. Samples X and Y are considered high calcium SS and sample Z is low calcium SS. The average chemical composition of the WG used is also shown in Table A. WG was made of soda-lime glass, which accounts for about 90% of the glass produced in the United States. It consists mainly of silicon dioxide (71.7% by weight), sodium oxide (12.1% by weight) and calcium oxide (9.4% by weight), other minor components include aluminum oxide and magnesium oxide. The composition of the glass reduces energy production costs because the material is densified by liquid phase sintering at lower temperatures than other glasses currently used in ceramic production. Depending on the SS composition, WG can be used as both an LCSAM to increase the densification temperature range and an HCSAM that acts as a flux to accelerate the densification. For example, WG can be used with sewage sludge samples X, Y and Z to produce a synthetic aggregate.

  The SS sample X and WG were processed as follows. In this example, WG was added to the dry SS powder and then pelletized.

  Sample X was dryer dried at 110 ° C. for 24 hours. The obtained dried cake was added to a ball mill and pulverized to obtain a powder. The mill was a Pascal Engineering Co., Ltd. model 21589 with approximately 2.172 kg of 3/4 inch (19.05 mm) high density alumina sphere grinding media. The ground powder was passed through a 150 micron sieve to remove coarse particles.

The WG used was derived in part from bottles and window glass separated from raw IBA. The WG was washed and dried in a dryer at 110 ° C. overnight. The WG is then crushed with a jaw crusher, separated to reduce the particle size to 2-6 mm, and then a vibrating ring is used to produce a tungsten carbide Tema mill (Gy-Ro, Glen Creston Ltd., (Available from Brownfields, England) so that 95% of the volume (d ₉₅ ) had a particle size of less than 710 microns. The particle size distribution was further reduced by dry grinding again with a carbide mill for an additional 4 minutes. This fine WG fraction was used in this example. The particle size d ₅₀ value of the crushed WG was 197.6 microns, which dropped to 19.8 microns after 4 minutes of dry grinding. In addition, WG from a wet milled slurry of IBA separated by a 710 micron sieve was also used. This fraction was also ground with a Tema dry mill for 4 minutes and combined with the first fraction.

  The ground WG was added to the sludge powder in specific proportions of 100% / 0%, 40% / 60%, 60% / 40% and 0% / 100% (SS / WG). The pulverized powder mixture of SS and WG is mixed with water (less than about 40% of the total dry weight of the resulting mixture) in a batch mixer and rotated at about 17 rpm at an angle of 30 ° to the horizontal direction with a diameter of 40 cm And fed to a rotating drum pelletizer having a length of 1 meter. The resulting “green” pellets were almost spherical or slightly angular. The average diameter was about 4 mm to about 9.5 mm. Pellets less than 4 mm were returned to the drum and pelletized again. Pellets larger than 9.5 mm were broken by hand into smaller pellets and again returned to the pelletizer.

  The pellets were coated with PFA from coal combustion by dusting PFA powder onto it. Next, the pellets were dried at about 110 ° C. and sent to a rotary kiln having a length of 1500 mm, an inner diameter of 77 mm, and a heating zone length of 900 mm. The kiln was set to operate at temperatures from 920 ° C. to 1220 ° C. for various SS / WG mixtures. The pellet was moved and rotated toward the rotary kiln tube at a rate of about 2.8 rpm for about 10 to about 12 minutes. In this example, the kiln was an electric fired rotary furnace available from Carbolite Hope Valley (UK) (GTFR 195 type). The fired pellets were discharged from the kiln and allowed to cool at room temperature.

  It should be noted that temperature-density curves (such as those shown in FIG. 1) can vary from kiln to kiln. For example, a curve corresponding to a particular percentage of SS and WG or other SAMs may have a maximum densification temperature that is slightly lower or higher than that using the particular kiln shown above. It is believed that the curve shift is due to a number of factors related to the operating efficiency of a particular kiln, such as temperature profile stability and energy loss. Thus, it may be necessary to prepare several samples in a particular kiln to ascertain the temperature range in which the aggregate has the desired properties.

Results Tables C to D below summarize the physical and mechanical properties of the aggregates formed in this example. It should be noted that these aggregates changed their properties greatly as the concentration of WG in SS increased.

Table C below summarizes the test results for aggregates containing different proportions of SS and WG fired at different temperatures (increased by 10 ° C.). The data is an average of 4 values for 100% sewage sludge and an average of 2 values for all WG containing samples. The data is plotted in the graph of FIG. The relative dry density of the calcined aggregate was calculated using Archimedes' method, and the water absorption was determined from the weight increase of the “surface dried” sample after being immersed in water for 24 hours.

  As explained above, as the amount of WG in the mixture increases, the chemical composition and mineralogy of the sewage sludge change with the increase in the amount of WG, so that the initial softening, maximum densification and complete or almost complete melting of the sample. The temperature interval between became wide. It was also observed that the temperature at which maximum densification occurs increases with increasing WG due to the increased concentration of silica present in the resulting mixture. For example, the SS of 100% Sample X has a maximum densification temperature of about 960 ° C. The mixture of sample X SS and WG at a ratio of 60% SS / 40% WG has a maximum densification temperature of 1030 ° C., and at a ratio of 40% SS / 60% WG, the maximum densification temperature is 1060 ° C. is there.

However, it has been recognized that the incorporation of WG into SS is not as effective in widening the temperature range at which the pellets sinter as other LCSAM incorporations. For example, 100% SS is sintered at a temperature range of about 930 ° C. to about 940 ° C. (10 ° C.) to form a lightweight aggregate of about 1.4 g / cm ³ to about 1.8 g / cm ^3. % SS / 40% WG is sintered at a temperature of about 970 ° C. to about 1000 ° C. (30 to about 35 ° C.) to form an aggregate in that density range. This temperature range is similar to that of the 40% SS / 60% WG pellet for the aggregate density range. This is believed to be due to the presence of high concentrations of sodium oxide and calcium present in the WG acting as a flux. It is also believed that the flux and molten glass produce a low viscosity melt, giving the product a higher density and lower porosity than other low calcium silicon aluminum materials.

As can be seen in FIG. 9 and Table C, for a given combination of SS and WG, the temperature can be used to determine the density and other characteristics of the sintered product. For example, for a 40% / 60% mixture of SS / WG, sintering at 1000 ° C. yielded LWA with a density of about 1.4 g / cm ³ , and sintering of the same mixture at 1060 ° C. resulted in density A normal-weight aggregate with a weight of about 2.6 g / cm ³ is obtained.

  Table C also shows the effect of adding WG on the water absorption of various aggregates. LWA produced at temperatures below the maximum densification temperature typically has some degree of porosity. As the maximum densification is approached, the pores are filled with molten material, so the size and number of pores gradually decreases to zero. Aggregates containing a large amount of SS show a rapid decrease in water absorption capacity with temperature, and high WG aggregates show a more gradual decrease in water absorption with temperature. 100% WG aggregate has a much lower water absorption than all other mixtures at all temperatures investigated because of the molten glass filling the pores created by evaporation.

Table D below summarizes the aggregate crush value ("ACV") as a percentage for a particular SS and WG mixture at the specified firing temperature. ACV is offered at three different temperatures for various percentages of WG / SS. ACV is inversely proportional to aggregate strength. The selected temperature was to produce different product properties and different microstructures for comparison. At relatively low temperatures in each combination, sintered LWA was produced according to a preferred embodiment of the present invention. At intermediate temperatures, a well-sintered or vitrified normal weight aggregate was obtained according to one embodiment of the present invention with few residual pores. At relatively high temperatures, vitrified LWA was also obtained according to one embodiment of the present invention.

  The ACV was relatively low and the strength of the aggregate was relatively high at the maximum densification temperature (intermediate temperature). Below that temperature, the density was relatively low, the ACV was relatively high, and the strength of the individual aggregate or bulk aggregate was relatively low. Above that temperature (intermediate temperature), ACV began to increase as density and aggregate strength decreased due to increased sample melting. Aggregate strength shows the same tendency of aggregate density with increasing temperature and, as expected, increases and then decreases. LWA comprising 40% SS and 60% WG at the temperatures shown in Table D according to an embodiment of the present invention is also lower ACV and higher than commercially available lightweight aggregate LYTAG with about 34% ACV, as shown below Has strength.

9 and Based on the calcination treatment temperature and WG effect of the addition on the properties of the calcined bone material shown in Tables C and D, and sintered at a temperature range of 1000 ° C. C. to 1100 ° C., about 1.4 g / ^cm 3 ~ A 40% SS / 60% WG mixture provided with an aggregate having a density of about 2.6 g / cm ³ is preferred. Such aggregates can be used in a wide range of applications, such as normal weight in concrete and use as LWA. This combination sinters at the widest temperature range of 100 ° C. to form the aggregate. Thus, the behavior of this mixture during sintering and other firing treatments and the final properties of the resulting aggregate are more easily controllable than with aggregates containing 100% SS. The low water absorption of this combination aggregate is due to the molten glass.

Table E shows some physical properties (relative dry density and water absorption and bulk density from Table C) and mechanical properties (from Table D) of a 40% SS / 60% WG mixture at three specific temperatures. ACV). The corresponding properties of commercially available aggregates LYTAG (sintered PFA) and OPTIROC (expanded clay) are also shown in Table E. Individual aggregate properties are the average of 20 measurements, and bulk aggregate properties are the average of the two measurements.

  From a comparison of the properties of aggregates containing 40% / 60% SS / WG blends sintered at 1000 ° C with LYTAG, WG-containing aggregates have individual and bulk aggregate densities comparable to those of LYTAG, higher It can be seen that it had a water absorption rate and a significantly lower ACV, and that it could withstand higher stress as a bulk when loaded under compression. OPTIROC has very low density, relatively low water absorption and very low strength. This is expected because OPTIROC has a honeycomb-like microstructure with a high volume of isolated spherical holes.

Example 2
In this example, high calcium SS samples X and Y and Group B, granite cutting residue (“GSR”), which is LCSAM (2.61% calcium oxide (CaO)), were included to produce synthetic aggregates. The average chemical composition of the SS samples and GSR used in these experiments is shown in Table F below. The same apparatus as that used in Example 1 was used in this example.

  SS samples X and Y and GSR were processed as described above and shown in FIG. GSR through a 250 mesh sieve (63 microns) was added to the dried sludge powder and the mixture was pelletized and calcined.

Add GSR powder to less than 63 microns through sieving to SS powder at specific ratios of 100% / 0%, 80% / 20%, 60% / 40% and 40% / 60% (SS / GSR) It was. As described above, water was added to the mixture in a batch mixer until the consistency of the mixture allowed pelletization (35% or less based on the total dry weight of the resulting mixture). The mixture was fed to a rotating drum and the pellets collected at the end of the drum were screened with 4 mm and 9.5 mm sieves. The pellets were coated with PFA (by spraying) and dried overnight in a dryer at about 110 ° C. The resulting green pellets were then sintered in a rotary kiln for about 10 to about 12 minutes. SS Sample X and pellets formed from GSR dust fired at a temperature of 9 7 0 ℃ ~1150 ℃, firing the pellets formed from the SS sample Y and GSR at 9 7 0 ℃ ~11 4 0 ℃ temperature.

Results Tables G to H below summarize the physical properties and mechanical properties of the aggregates formed by the above methods.

The relative dry density and water absorption of the aggregate were determined according to the method described in Example 1. In this example, compressive strength was calculated by applying a load to each individual aggregate between two parallel plates until failure. From the stress analysis, it is clear that when one sphere is examined in this way at two opposite positions with respect to diameter, the compressive strength σ of the sphere is given by the following equation:

  Where “IACS” = individual aggregate crush strength, d = sphere diameter (mm) and P = break load (N). The average compressive strength was calculated from tests performed on at least 12 aggregates made at each temperature. The load was applied by a compression tester until the aggregate broke down. The instrument's dial gauge provides a reading that indicates the load causing the failure. The load was calculated from the reading by the following equation: Load (pound) = 550.95 (reading) -1620.7; Load (kg) = Load (pound) /2.205).

Table G below summarizes test results for aggregates containing various proportions of SS and GSR at different temperatures for the two samples X and Y. Data is plotted in the graphs of FIGS. 1 and 10 for samples X and Y, respectively. Table G also summarizes the IACS results for specific SS and GSR mixtures at specified sintering temperatures. As described above, when the concentration of LCSAM (GSR in this example) in the mixture increases, the initial softening, maximum densification, and complete or completeness of the sample due to changes in sewage sludge chemical composition and mineralogy due to GSR dust. The temperature interval between almost complete melting was widened.

  Aggregate water absorption from mixtures containing high concentrations of SS, specifically sample X, decreases rapidly with increasing temperature, but aggregates from mixtures with relatively large amounts of GSR are associated with temperature. The decrease in water absorption is more gradual. As expected, IACS shows a trend similar to density, rising to the temperature of maximum densification and decreasing at higher temperatures. The increase in aggregate strength with increasing temperature is rapid for aggregates from a 100% SS mixture and becomes more moderate as the amount of GSR increases.

Based on these results, the preferred SS / GSR mixture for producing sintered products that can be used in a wide range of applications such as LWA in concrete is 40% / 60% for both samples X and Y. SS / GSR mixture. Aggregate produced from a mixture of SS containing GSR is sintered in a wider temperature range than SS alone, so that the behavior and final properties of the aggregate can be easily controlled. 40% / 60% SS / GSR mixture, for example in the case of the sample X is sintered at a temperature range of 1000 ℃ ~10 8 0 ℃, density to form a LWA is less than 2.0 g / cm ³ . Aggregates having the desired properties and characteristics (porosity, density, strength) can be more easily produced.

As apparent from FIGS. 1 and 10 and Table G, aggregates having a predetermined density and other characteristics for a given combination of SS and GSR when the characteristics and composition of the SS are known by temperature control. Can be manufactured. For example, using Sample X , a 40% / 60% mixture of SS / GSR, sintering at 1000 ° C. yields an LWA having a density of about 1.4 to about 1.5 g / cm ³ and about Sintering at 1110 ° C. resulted in a normal weight aggregate having a density of about 2.5 g / cm ³ .

Table H shows the physical properties (relative dryness and bulk density, water absorption rate) of the 40% / 60% SS / GSR mixture of sample Y at four different temperatures, along with the corresponding properties of LYTAG aggregate. ) And mechanical properties (ACV). Aggregates produced at temperatures below the maximum densification temperature had a density of less than 2.0 g / cm ³ , relatively low water absorption and high strength. It was therefore very suitable for use with lightweight concrete. LYTAG had a lower relative density and aggregate strength than these aggregates.

Example 3
In this example, the calcined aggregate containing slate that is SS of sample Y, moderately high calcium SS (calcium oxide (CaO) 12.12%) and LCSAM (calcium oxide (CaO) 1.82%) Manufactured. The average chemical analysis of sample Y SS and slate used in these experiments is shown in Table I below. In these experiments, sewage sludge sample Y was used. The same equipment used in Example 1 is used here.

  The slate was processed as described in FIG. 6 and described in more detail in the previous examples.

The sewage sludge was dried at 110 ° C. for 24 hours, and then the solid cake was pulverized into a fine powder. Slate was added to the sewage sludge powder in specific proportions of 100% / 0%, 80% / 20%, 60% / 40% and 40% / 60% (SS / slate). Water was added to the mixture in a batch mixer (less than 45% based on the total dry weight of the resulting mixture) to form a clay-like mixture for pelleting. Because slate has a fine particle size distribution, it was mixed directly with SS powder. Before further processing with SS, the slate may need to be crushed to a fine size. The obtained green pellets were in the range of 4 mm to 9.5 mm. Pellets containing slate were coated with slate powder, dried at 110 ° C. and sent to the rotary kiln. The resulting pellet after firing about 10-12 minutes at a temperature of 9 7 0~1 21 0 ℃, discharged from the kiln was allowed to cool to room temperature.

Results Tables J-K below summarize the physical properties and mechanical properties of the fired aggregates from the specific SS / slate mixture and the firing temperature. The relative dry density and water absorption of the calcined aggregate were determined according to the method described in Example 1. The compressive strength of individual aggregates was also defined as the aggregate strength mass index (“ASMI”) as follows:

Where P = fracture load (kg) and m = mass of pellet (kg). The average value of the compressive strength was calculated from tests conducted on at least 12 types of aggregates manufactured at each firing temperature and at different ratios.

Table J summarizes the physical property results (relative dry density, water absorption) and mechanical properties ( ASMI). The data is plotted on the graph of FIG. As explained above, increasing the slate concentration in the mixture resulted in a wider temperature interval between the initial softening, maximum densification and melting point of the sample due to SS chemical composition and mineralogy changes due to slate . .

The water absorption of pellets from a mixture containing a high concentration of SS decreases more rapidly with increasing temperature, while the pellets from a mixture containing a large amount of slate show a slower decrease in water absorption with temperature. IACS and ASMI show a trend similar to density as expected, rising to the temperature of maximum densification and decreasing at higher temperatures. The increase in aggregate strength with increasing temperature is more rapid for the pellets from the 100% SS mixture and becomes more moderate with increasing amount of slate in the mixture.

Based on the temperature and the effect of slate addition on the properties of the sintered aggregate, the density was about 1.6 g / cm ³ to about 2.4 g / cm ³ at temperatures ranging from 10 80 ° C. to 1160 ° C. A sintered 40% / 60% sample Y SS / slate mixture is preferred. The behavior of this mixture during sintering and the final properties of the resulting sintered LWA can be more easily controlled and made easier than SS of 100% sample Y and other combinations of SS and slate. By processing SS / slate pellets at lower temperatures than those used in these experiments, aggregates with lower density and higher water absorption can also be produced.

Table K summarizes the physical properties of the LYTAG aggregate .

As shown by Table J and FIG. 11, by controlling the temperature, an aggregate having a predetermined density and other characteristics can be produced for a predetermined combination of SS and slate. Depending on the aggregate properties required, this combination can produce lightweight aggregates with properties comparable to or better than LYTAG.

Table L summarizes the behavior of calcined aggregates obtained from a mixture of SS and slate. The temperature range at which the aggregate is fired, the corresponding density, water absorption and ASMI range, and the maximum densification temperature for different types and proportions of slate / sewage sludge are shown.

Example 4
In this example, a synthesis comprising sample Z, low calcium SS (calcium oxide (CaO) 3.20%) and cement kiln dust (“CKD”), Group A HCSAM (calcium oxide (CaO) 63.6%). Aggregates were manufactured. The average chemical composition of CKD used in these experiments is shown in Table M below.

The SS and CKD of sample Z were processed as described above and shown in FIG. SS was dried at 110 ° C. for 24 hours and pulverized to a fine powder. CKD having a fine particle size distribution (95% of the particle volume (d ₉₅ ) finer than 45 microns) was added to the dry SS powder, and then the mixture was pelletized and calcined.

CKD was added to the SS powder in specific proportions of 100% / 0%, 95/5% and 90% / 10% (SS / CKD). The powder was mixed with water (below 35% based on the total dry weight of the resulting mixture) in a batch mixer until the consistency of the mixture allowed pelletization. The mixture was fed to a rotating drum and pellets were collected at the end of the drum and sieved with 4 mm and 9.5 mm sieves. The pellets were coated with CKD and dried overnight in a dryer at about 110 ° C. The obtained green pellets were fired in a rotary kiln at a temperature of 940 ° C. to 1110 ° C. for about 10 to about 12 minutes .

Results Tables N-O below summarize the physical and mechanical properties of the aggregates formed by the above methods. The relative dry density, water absorption and ASMI of the aggregate were determined according to the methods described in the above examples.

Table N below summarizes the test results for aggregates containing different proportions of SS and CKD sintered at different temperatures. The data is plotted in the graph of FIG. Table O summarizes the physical property results (relative dry density and water absorption from Table N) and mechanical properties (ASMI from Table N). By increasing the CKD concentration in the mixture, the composition of the initial mixture was changed, so that the firing temperature range was slightly narrowed. Since CKD has such a high calcium content, the amount needed to increase the mobility of the melt and the densification of the pellets of the mixture was negligible.

  Due to the higher density obtained by the relatively low amount of flux in the mixture, the aggregate water absorption from the high concentration SS mixture is relatively low. As expected, ASMI shows a trend similar to density, rising to the maximum densification temperature and decreasing at higher temperatures. Adding CKD with SS samples having a lower calcium oxide concentration than the sample Z used in these examples is expected to be more important than shown in this example, and in order to obtain the desired aggregate composition, It is believed that a high concentration of CKD needs to be added to the SS.

Based on the temperature on the properties of the sintered aggregate and the effect of CKD addition, temperatures in the range of 940 ° C. to 1090 ° C., where pellets with a density of about 1.4 g / cm ³ to about 2.0 g / cm ³ were produced. An SS / CKD mixture of 90% / 10% sample Z sintered with Such aggregates can be used in a wide range of applications, including as a lightweight aggregate in concrete. However, in the case of sample Z SS used in this example, the initial SS already contains a small amount of fluxing agent such as calcium oxide in the composition, so even a 95% / 5% SS / CKD mixture. Can be selected for aggregate production. When the aggregate from the SS / CKD mixture is fired at a lower temperature than that used in this example, an aggregate having a relatively low density and a relatively high water absorption can be produced. The presence of the flux in the material is believed to provide an aggregate having properties superior to the fired aggregate from a material that does not contain the flux by further increasing the packing and densification of the particles.

Table O summarizes certain physical and mechanical properties of aggregates from a 90% / 10% mixture of SS / CKD at three specific temperatures.

  As described above, by controlling the firing temperature, it is possible to produce an aggregate having a predetermined density and other characteristics for a predetermined combination of SS and CKD.

Example 5
In this example, a synthetic aggregate containing sewage sludge (sample Z) and limestone was produced. The average chemical composition of limestone used in these experiments is shown in Table P below.

SS (sample Z) and limestone powder were described above and processed as shown in FIG. SS was dried at 110 ° C. for 24 hours, and then the solid cake was pulverized to obtain a fine powder. Limestone was added to the dried sludge powder and then the mixture was pelletized and fired.

  Limestone was added to the SS powder in specific proportions of 100% / 0%, 95/5% and 90% / 10% and 80% / 20% (SS / limestone). The powder was mixed with water in a batch mixer until the consistency of the mixture was pelletizable (less than 32% based on the total dry weight of the resulting mixture). The mixture was fed to a rotating drum and the pellets collected at the end of the drum were screened with 4 mm and 9.5 mm sieves. The pellets were coated with limestone and then dried overnight in a dryer at about 110 ° C. The resulting green pellets were fired in a rotary kiln at a temperature of 940 ° C. to 1110 ° C. for about 10 to about 12 minutes.

Results Tables Q to R below summarize the physical properties and mechanical properties of the aggregates formed by the above methods. The relative dry density, water absorption and ASMI of the aggregate were determined according to the methods described in the above examples.

Table Q below summarizes the test results for sintered aggregates containing different proportions of SS and limestone sintered at different temperatures. The data is plotted in the graph of FIG. Table R, summarizes the objects of our and mechanical properties of the particular aggregate. As the concentration of limestone in the mixture increased, the temperature range at which the aggregate was fired was slightly narrowed.

  Due to the higher density obtained by the relatively low amount of flux in the mixture, the water absorption rate of the aggregate from the mixture with high concentrations of sewage sludge is relatively low. As expected, ASMI shows a trend similar to density.

The addition of limestone to an SS sample having a lower calcium oxide concentration than the sample Z used in this example is expected to have a greater effect than in the present invention. Based on the effect of temperature and limestone addition on the properties of sintered aggregate, an aggregate having a density of about 1.6 g / cm ³ to about 2.4 g / cm ³ for use as a normal weight or light weight aggregate give, 90% / 10% SS / limestone mixture calcined at a temperature range 940 ℃ ~1 09 0 ℃ is preferred. However, in the case of the SS sample used in this example, the initial SS already has some amount of calcium oxide as a flux in the composition, so even if it is a 95% / 5% SS / limestone mixture, It is considered preferable in the manufacture of materials.

Table R summarizes some physical and mechanical properties of aggregates from 90% / 10% SS / limestone blends at three specific temperatures.

Example 6
In this example, a synthetic aggregate containing (Sample Z) and MSW incinerator fly ash (“IFA”) was produced. The average chemical composition of the incinerator fly ash used in these experiments is shown in Table S below.

  SS (Sample Z) and IFA were processed as described above and shown in FIG. SS was dried at 110 ° C. for 24 hours, and then the solid cake was pulverized to obtain a fine powder. After IFA was added to the dry SS powder, the mixture was pelletized and fired.

  IFA was added to the SS powder in specific proportions of 100% / 0%, 95/5%, and 90% / 10% and 80% / 20% (SS / IFA). The powder was mixed with water in a batch mixer until the consistency of the mixture could be pelletized (37% or less based on the total dry weight of the resulting mixture). The mixture was fed to a rotating drum and the pellets were collected at the end of the drum and sieved with 4 mm and 9.5 mm sieves. The pellets were coated with fly ash and dried overnight in a dryer at about 110 ° C. The obtained pellets were calcined in a rotary kiln at a temperature of 980 ° C. to 1110 ° C. for about 10 to about 12 minutes.

The results in Table T~U below, summarizes the object of the aggregate formed by the above method. The data is plotted on the graph of FIG. Increasing the IFA concentration in the mixture changed the SS chemical composition and mineralogy, which slightly narrowed the temperature interval between initial softening, maximum densification and melting of the sample.

Based on the effects of temperature and IFA addition on the properties of the aggregate, in terms of density producing aggregate is 1.5g ^/ cm ³ ~2.4g ^/ cm 3 is, 80% / 20% SS / IFA mixture preferable. However, a 90% / 10% SS / IFA mixture in the same calcination temperature range is also preferred.

Table U summarizes certain physical properties of aggregates from an 80% / 20% mixture of SS / IFA at three specific temperatures.

Example 7
In this example, a synthetic aggregate containing SS (sample Z) and ground blast furnace slag (“G GB S”) was produced. The average chemical composition of GBS used in these experiments is shown in Table V below.

SS For (Sample Z) and G G BS, described above, was processed as shown in FIG. After drying SS at 110 ° C., the solid cake was pulverized into a fine powder. G GB S was added to the dried sludge powder, and then the mixture was pelletized and fired.

100% / 0%, in a specific ratio of 95/5% and 90% / 10% and 80% / 20% (SS / G G BS), was added G G BS sludge powder. The powder was mixed with water in a batch mixer until the consistency of the mixture was pelletizable (35% or less based on the total dry weight of the resulting mixture). The mixture was pelletized and the pellets were screened with 4 mm and 9.5 mm sieves. The pellets were coated with GG BS and then dried overnight in a dryer at about 110 ° C. The obtained pellets were fired in a rotary kiln at a temperature of 970 ° C. to 1110 ° C. for about 10 to about 12 minutes.

Results Table W~X below, summarizes the object of the aggregate formed by the above method. Table W below summarizes the test results for aggregates containing different proportions of SS and GBS fired at different temperatures. The data is plotted in the graph of FIG. Similar effects to CKD, IFA and limestone were observed with respect to increased GBS concentrations in the sewage sludge mixture.

Based on the effects of temperature and G G BS addition on the properties of the aggregate to be produced, 980 ℃ ~1110 aggregate density is sintered at ° C. of about 1.5 g / cm ³ ~ about 2.4 g / cm ³ An 80% / 20% SS / G G BS mixture that gives a However, in the case of SS sample Z used in this example, since the first SS already has a small amount of a flux component such as calcium oxide in the composition, it is 90% / 10% SS / G BS mixture. Even so, it can be effective in aggregate production.

Table X summarizes some physical properties of aggregates from 80% / 20% SS / GG BS pellets.

Example 8
In this embodiment, pulverized fuel ash and London clay is a low calcium silicon aluminum material, a mixture of a blast furnace slag Ru high calcium silicon aluminum material der ( "BF S") and lime waste, synthetic bone material Manufactured. BFS was ground. Waste glass was also used in the mixture as either a low calcium silicon aluminum material or a high calcium silicon aluminum material. The average composition of waste glass are those shown in Example 1 above follow. The important component of the PFA and G G BS, are shown in Table Z1 below.

Since these materials had a fine particle size distribution, they were mixed directly with each other without grinding . Clay at a rate ranging from 10% to 30% by total weight of the dry weight of the mixture was added as a plastic binding material. Table Z2 shows the materials used in aggregate production and their proportions, where the low calcium silicon aluminum material is material 1 and the high calcium silicon aluminum material is material 2.

These materials were mixed in the above proportions, and pelletized by adding water using the apparatus described in the above examples. The pellets were then dried overnight in a dryer at about 110 ° C. The resulting pellets were calcined in a Trefoil rotary kiln having a three-leaf clover-like shape using propane as a fuel at a temperature of about 1000 ° C. to about 1250 ° C. for about 15 to about 20 minutes. The aggregate was air cooled.

The aggregate retained integrity when removed from the kiln. It was almost spherical or slightly angular, and the color varied depending on the mixture. For example, although aggregates containing a large amount of G G BS looked white-like, aggregates containing a large amount of PFA appeared to be dark brown. These aggregates had a hard, smooth surface and were lightweight. They had a relatively hard structure when randomly crushed.

  The embodiments described herein are illustrative of the practice of the invention. Changes may be made to these examples without departing from the spirit and scope of the invention as defined by the appended claims.

FIG. 4 is a graph of density (g / cm ³ ) versus calcination temperature (° C.) for a mixture of sewage sludge (Sample X) and sewage sludge and granite cutting residue according to one embodiment of the present invention. It is a graph of the density (g / cm < ³ >) with respect to the calcination process temperature (degreeC) about the mixture of the sewage sludge and the sewage sludge and cement kiln dust by one Embodiment of this invention. It is typical sectional drawing of an example of the aggregate manufactured by the method of this invention. It is typical sectional drawing of an example of the sintered aggregate by embodiment of this invention. It is typical sectional drawing of an example of the vitrification aggregate by embodiment of this invention. It is an example of the aggregate manufacturing method by one Embodiment of this invention. It is a photograph of an example of the sintered aggregate by embodiment of this invention. It is an example of another aggregate manufacturing method by another embodiment of the present invention. It is a graph of the density versus firing treatment temperature for the mixture of sewage sludge and sewage sludge and waste glass according to an embodiment of the present invention (℃) (g / cm 3 ). It is a graph of the density (g / cm < ³ >) with respect to the calcination process temperature (degreeC) about the mixture of sewage sludge (sample Y) and the sewage sludge and the granite cutting residue by one Embodiment of this invention . It is a graph of the density versus firing treatment temperature for the mixture of sewage sludge and sewage sludge and slate in accordance with one embodiment of the present invention (℃) (g / cm 3 ). It is a graph of the density versus firing treatment temperature for the mixture of sewage sludge and sewage sludge and limestone according to an embodiment of the present invention (℃) (g / cm 3 ). It is a graph of the density (g / cm < ³ >) with respect to the calcination process temperature (degreeC) about the mixture of the sewage sludge by one Embodiment of this invention, and a sewage sludge and an incinerator fly ash. It is a graph of the density (g / cm < ³ >) with respect to the calcination process temperature (degreeC) about the mixture of the sewage sludge by one Embodiment of this invention, and a sewage sludge and a grinding | pulverization granular blast furnace slag.

Claims (28)

Mixing sewage sludge from a wastewater treatment facility with non-coal ash silicon aluminum waste, wherein the waste contains more calcium than the sewage sludge;
Agglomerating the mixture to form an aggregate; and firing the aggregate in a rotary kiln to form a vitreous crystalline porous lightweight aggregate having a relative density of less than 2 g / cm ^3. A method for manufacturing lightweight aggregates.   The method of claim 1, wherein the waste comprises more than 9% calcium by dry weight and the sewage sludge comprises less than 3% calcium by dry weight.   The method of claim 1, wherein the aggregate comprises less than about 10% calcium by dry weight.   The method of claim 1, comprising mixing about 90% to about 60% sewage sludge by dry weight of the mixture with about 10% to about 40% of the waste by dry weight of the mixture.   The method of claim 1, further comprising controlling one or more specific characteristics of the aggregate based at least in part on a ratio of the sewage sludge to the waste and a firing temperature.   The method of claim 5, comprising controlling the density of the aggregate based at least in part on the ratio and the temperature.   The method of claim 1, comprising firing the aggregate to a temperature at which the aggregate sinters to form a sintered lightweight aggregate.   The method of claim 1, comprising vitrifying the aggregate to a temperature at which vaporization and trapping of the vaporized gas in the molten liquid phase occurs, thereby expanding the aggregate to form a lightweight aggregate. .   The method of claim 1, comprising agglomerating the mixture by pelletization.   The method of claim 1, comprising agglomerating the mixture by extrusion.   The method of claim 1, wherein the waste comprises one or more of incinerator residue, waste glass, blast furnace slag, kiln dust or mining waste.   The method of claim 11, wherein the incinerator residue comprises one or more of incinerator bottom ash, incinerator fly ash, or incinerator filter dust. Mixing sewage sludge from a wastewater treatment facility with non-coal ash silicon aluminum waste, wherein the waste contains less calcium than the sewage sludge;
Agglomerating the mixture to form an aggregate; and firing the aggregate in a rotary kiln to form a vitreous crystalline porous lightweight aggregate having a relative density of less than 2 g / cm ^3. A method for manufacturing lightweight aggregates.   The method of claim 13, wherein the waste comprises one or more of mining waste or waste glass.   The method of claim 13, wherein the waste comprises less than about 10% calcium.   The method of claim 13, wherein the aggregate comprises less than about 10% calcium by dry weight.   14. The method of claim 13, comprising mixing about 30% to about 70% sewage sludge by dry weight of the mixture with about 70% to about 30% of the waste by dry weight of the mixture.   14. A method according to claim 13, comprising agglomerating the mixture by pelletization.   14. The method of claim 13, comprising agglomerating the mixture by extrusion.   14. The method of claim 13, comprising firing the aggregate to a temperature at which the aggregate sinters to form a sintered lightweight aggregate.   14. The method of claim 13, comprising vitrifying the aggregate to a temperature at which vaporization and trapping of the vaporized gas in the molten liquid phase occurs, thereby expanding the aggregate to form a lightweight aggregate. .   14. The method of claim 13, further comprising controlling one or more specific characteristics of the aggregate based at least in part on a ratio of the sewage sludge to the waste and a firing temperature.   23. The method of claim 22, comprising controlling the density of the aggregate based at least in part on the ratio and the temperature. Mixing sewage sludge from a wastewater treatment facility with non-coal ash silicon aluminum waste, wherein the waste contains more than 9% calcium by dry weight, and the sewage sludge is less than 3% by dry weight Including calcium;
Agglomerating the mixture to form an agglomerate; and calcining the agglomerate in a rotary kiln to have pores and a relative density of less than 2 g / cm ³ and a water absorption of less than 30% at dry weight A method for producing a lightweight aggregate, comprising the step of forming a porous porous lightweight aggregate.   25. The method of claim 24, comprising firing the aggregate to a temperature at which the aggregate sinters to form a sintered lightweight aggregate.   25. The method of claim 24, comprising vitrifying the aggregate to a temperature at which vaporization and trapping of the vaporized gas in the molten liquid phase occurs, thereby expanding the aggregate to form a lightweight aggregate. . Mixing sewage sludge from a wastewater treatment facility with non-coal ash silicon aluminum waste, wherein the waste contains less calcium than the sewage sludge;
Agglomerating the mixture to form an aggregate; and calcining the aggregate to a temperature at which the aggregate expands to absorb no more than 10% water by pores and a relative density of less than 2 g / cm ³ and dry weight A method for producing a lightweight aggregate, comprising the step of forming a lightweight aggregate having a rate.   28. The method of claim 27, comprising firing the agglomerates to cause vaporization and trapping of the vaporized gas, thereby expanding the agglomerates.