KR20160027826A - Artificial lightweight aggregate using waste and manufacturing method thereof and manufacturing system thereof - Google Patents

Abstract

The present invention relates to an artificial lightweight aggregate using waste such as sludge, incineration ash, soil waste, etc., a method for manufacturing the same, and a system for manufacturing the same and, more specifically, to an artificial lightweight aggregate using waste, having high ratio of an inorganic additive in a first mixture for manufacturing the artificial lightweight aggregate, enabling easy stirring of the mixture by adding an organic additive, simplifying a manufacturing process by removing a sludge drying process, reducing the production facility costs and energy costs, having enough light weight, and increasing productivity of the artificial lightweight aggregate. The present invention also relates to a method for manufacturing the artificial lightweight aggregate, and a system for manufacturing the same.

Description

TECHNICAL FIELD [0001] The present invention relates to an artificial lightweight aggregate using waste, a method for manufacturing the same and a system for manufacturing the same.

The present invention relates to an artificial lightweight aggregate using waste, a method for producing the same and a system for manufacturing the same, and more particularly, to a method for manufacturing an artificial lightweight aggregate by increasing the ratio of an inorganic additive to an initial mixture for producing an artificial lightweight aggregate, A method for manufacturing the artificial lightweight aggregate, a method for manufacturing the artificial lightweight aggregate, a method for manufacturing the artificial lightweight aggregate, a method for manufacturing the artificial lightweight aggregate, a method for manufacturing the artificial lightweight aggregate, .

The development of industry and the concentration of population in large cities have caused various environmental problems, one of which is the increase in sewage sludge generation as sewage treatment capacity increases. Sewage sludge contains a considerable amount of organic matter and is subject to decay. Therefore, it needs to be treated quickly. However, as regulations on environmental pollution are strengthened, simple landfill or marine emission is regulated by the Waste Management Act or international convention, and a new method of treating sewage sludge is required. A method of recycling sewage sludge has been devised, and Korean Patent Registration Nos. 10-0849765, 10-0347997 and 10-1066193 disclose a method for producing an artificial lightweight aggregate using sewage sludge.

However, the methods disclosed in the above-mentioned patent publication need to dry the sludge first and then mix it with an inorganic material such as clay, and then remove the moisture by using expensive equipment such as a sludge dryer, And energy costs. Therefore, a method of manufacturing an artificial lightweight aggregate capable of saving enormous energy costs while securing sufficient lightweight has been required.

Korean Patent Registration No. 10-0849765 Korean Registered Patent No. 10-0347997 Korean Registered Patent No. 10-1066193

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a method for manufacturing a lightweight aggregate of artificial lightweight aggregate, in which the ratio of the inorganic additive to the initial mixture is increased, , Owing to omission of the sludge drying process, enormous energy costs associated with sludge drying and production equipment costs of high-priced equipment such as a sludge dryer are reduced, and artificial lightweight aggregates using artificial waste Lightweight aggregate, a method of manufacturing the same, and a system for manufacturing the same.

These and other objects and advantages of the present invention will become more apparent from the following description of a preferred embodiment thereof.

The above object is achieved by a method of producing a sludge comprising a sludge having a water content of 70 to 80% by weight, an inorganic additive having a water content of 10% by weight or less and an organic additive, wherein the weight ratio of the sludge: inorganic additive is 1: , And the organic additive can be achieved by an artificial lightweight aggregate of 5 to 20% by weight based on 100% by weight of the total mixture.

Preferably, the sludge may be sewage sludge or wastewater sludge originating from the papermaking and manufacturing plants.

Preferably, the inorganic additive may be at least one of an ash, ash, coal ash and stone powder.

Preferably, the organic additive may be at least one of sawdust, rice hulls, and food waste.

The object is achieved by mixing a sludge having a water content of 70 to 80% by weight, an inorganic additive having a water content of 10% by weight or less and an organic additive to produce a mixture having a water content of more than 20% by weight and not more than 40% by weight; A molding and drying step in which the mixture is formed into a spherical shaped body and dried to a water content of 20 wt% or less; And a sintering step of sintering the spherical shaped body at 1100 to 1200 ° C for 10 to 30 minutes.

Preferably, the weight ratio of the sludge: inorganic additive in the mixing step is 1: 1.5 to 5, and the organic additive may be 5 to 20 wt% based on 100 wt% of the mixture.

The object is achieved by a sludge storage device comprising: a reservoir 1 for storing sludge; A reservoir 2 for storing an inorganic additive; A reservoir 3 for storing the organic additive; A quantitative feeder 1 for supplying a sludge in a quantitative manner; A quantitative feeder 2 for quantitatively feeding an inorganic additive; A quantitative feeder 3 for quantitatively feeding an organic additive; A non-gravity mixer for evenly mixing the sludge, mineral additive and organic additive supplied by the metered feed devices 1 to 3; A continuous kneader for compressing the mixed mixture in a zero-gravity mixer; A kneader for pre-forming the compressed mixture in the continuous kneader; A ventilator for shaping the mixture discharged from the shoemaker into a spherical shape; A surface dryer for drying the spherical shaped body manufactured in the ventilation system before firing; And a sintering furnace for sintering the spherically shaped body surface-dried in the surface drier.

Preferably, the system for producing the artificial lightweight aggregate may further include an air pollution prevention facility and a wastewater treatment facility. The air pollution prevention facility may include a gas and dust collecting gas generated in the process of producing the artificial lightweight aggregate, Duct collecting duct (DUCT) system; A dehumidifying tower for removing odors by treating gas and dust; Filter dust collector; And a wet scrubbing tower.

According to the present invention, mixing of the mixture can be facilitated and the sludge drying process can be omitted by increasing the ratio of the inorganic additive to the initial mixture for producing the artificial lightweight aggregate and adding the organic additive capable of securing the heat amount It is economical because of the enormous energy cost to reduce moisture contained in sludge and the cost of production equipment such as sludge dryer, and it has the effect of dramatically increasing productivity while ensuring sufficient light weight of artificial lightweight aggregate. I have. In addition, it has the effect of contributing to the environmental preservation by making it easy to remove the odor that may occur in the process of manufacturing the artificial lightweight aggregate by reducing the proportion of the sludge by recycling the waste.

 However, the effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art from the following description.

1 is a process diagram for explaining a system for manufacturing an artificial lightweight aggregate according to an embodiment.
2 is a process diagram for explaining a system for manufacturing a conventional artificial lightweight aggregate.

Hereinafter, the present invention will be described in detail with reference to embodiments and drawings of the present invention. It will be apparent to those skilled in the art that these embodiments are provided by way of illustration only for the purpose of more particularly illustrating the present invention and that the scope of the present invention is not limited by these embodiments .

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification, including definitions, will control.

Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described herein.

The artificial lightweight aggregate utilizing waste according to one aspect of the present invention is produced from a mixture comprising sludge having a water content of 70 to 80 wt%, an inorganic additive having a water content of 10 wt% or less and an organic additive, wherein the weight ratio of the sludge: 1: 1.5 to 5, and the organic additive may be 5 to 20% by weight based on 100% by weight of the mixture.

Although the sludge is described herein as sewage sludge, it is not limited thereto, and the sludge may be sewage sludge or wastewater sludge originating in papermaking and manufacturing plants. Among the properties of sewage sludge, moisture content is one of the important factors in the design of treatment apparatus. Depending on the moisture content, the drying conditions of the dryer applied during the pretreatment process are affected. The sewage sludge generated in the sewage treatment plant has a water content of about 77 to 85% by weight and an average water content of about 80% by weight. In order to minimize the loss of auxiliary materials and energy in the treatment of the sludge, it is preferable to dehydrate to 80% or less at the time of dewatering, and more preferably 70 to 80% for effective treatment.

The inorganic additive is a substance that can impart moldability by having a point clotting force and foaming property and can make a pore well, and can be an ash, a loess, a coal ash, a stone powder and the like. It is preferable that the water content of the inorganic additive is 10% by weight or less, since it is advantageous to adjust the water content of the mixture by using the dry additive. Therefore, it is needless to say that, in the case of the inorganic additive, the moisture content may be 0% by weight and may not contain moisture at all. If it is more than 10% by weight, the water content is high, which is disadvantageous in adjusting the water content of the mixture.

The organic additive facilitates the agitation of the mixture and makes it possible to ensure sufficient lightweight properties of the artificial lightweight aggregate by supplementing the shortage of the organic matter contained in the sludge in the sintering step to be described later. The heat of the sawdust, rice hull, Anything that can be secured is possible.

The weight ratio of sludge: mineral additive is preferably 1: 1.5-5. If the above range is exceeded, the water content of the sludge can not be lowered to 40% by weight or less, which may cause difficulty in mixing and molding, and the drying process may be uneconomical due to the occurrence of a glue zone to be described later. The organic material additive is preferably 5 to 20% by weight based on 100% by weight of the whole mixture for producing the lightweight aggregate. If the organic additive is less than 5% by weight, the amount of self-heating of the molded product may be insufficient to produce artificial lightweight aggregates with good lightweight properties. If the organic additive is more than 20% by weight, This is because lightweight aggregate can be produced in excess of artificial lightweight aggregate. The ratio of the inorganic additive to the mixture for producing the artificial lightweight aggregate is increased and the drying process of the sludge can be omitted by adding the organic additive. The glue zone means that when the water content of the sludge is more than 40% by weight and less than 60% by weight, only the outer surface of the sludge is dried and the inner moisture is not dried. Therefore, in order to dry the sludge at 40 wt% or less avoiding the dead zone, an enormous energy cost is required, and expensive equipment such as a sludge dryer is required. However, when the ratio of the inorganic additive is increased during the initial mixing and when the organic additive is added to the mixture, the water content of the mixture is reduced to 40% by weight or less without requiring equipment such as a sludge dryer, Economical. In addition, the organic additive can compensate for the amount of organic matter required in the firing process, thereby ensuring sufficient lightweightness of the artificial lightweight aggregate and increasing the productivity.

The weight ratio of the sludge: inorganic additive and the proportion of the organic additive is not limited to the above-mentioned ratio. That is, it may vary depending on the characteristics and kinds of the sludge, the inorganic additive, and the organic additive.

A method for producing an artificial lightweight aggregate according to another aspect of the present invention comprises mixing a sludge having a water content of 70 to 80 wt%, an inorganic additive having a water content of 10 wt% or less, and an organic additive to produce a mixture having a moisture content of more than 20 wt% A mixing step; A molding and drying step in which the mixture is formed into a spherical shaped body and dried to a water content of 20 wt% or less; And a sintering step of sintering the spheroidally shaped body at 1100 to 1200 ° C for 10 to 30 minutes.

In the mixing step, it is important to avoid glue zones. For this purpose, the ratio of inorganic additives is increased and the water content of the mixture is lowered to 40% by weight or less by adding an organic additive. When the water content is more than 40% by weight, the molding is not well performed in the molding step due to the characteristic of the glue zone. The water content is preferably as low as possible, but usually the water content is more than 20% by weight but not more than 40% by weight. The mixing can be done in a zero-gravity mixer described below.

In the mixing step, the weight ratio of the sludge to the inorganic additive is 1: 1.5 to 5, and the organic additive is preferably 5 to 20 wt% based on 100 wt% of the mixture. Outside of the above range, the above limitations are problematic.

In the molding step, the mixture produced in the mixing step is made into a spherical shaped body. Since the molding method has a different strength depending on the molding machine or molding method and affects the strength after firing, it is necessary to appropriately provide the strength of the molding according to the final use of the artificial lightweight aggregate. In this specification, the artificial lightweight aggregate has been described as a spherical molded body for the purpose of using the artificial lightweight aggregate. However, when the artificial lightweight aggregate is used for other purposes, it may be molded in a shape other than spherical. When sintering is carried out at a high moisture content, the lightweight property can not be secured and the shape of the artificial lightweight aggregate can be deformed. Accordingly, the manufactured spherical molded body can be dried before proceeding to the firing step, and when dried at a moisture content of 20 wt% or less through the surface dryer, the lightweight property can be secured and the plasticity strength can be increased.

In the sintering step, the spherical shaped body having a water content of not more than 20% by weight is fired in a reducing atmosphere so as to have lightweight, absorbent, adsorbing functionality and mechanical strength. The organic material becomes porous when the organic material is oxidized in the calcination of the reducing atmosphere. Since the strength and the functionality of the artificial lightweight aggregate depend on the firing temperature, an appropriate temperature should be selected depending on the use of the artificial lightweight aggregate. It is preferable that the firing is performed at 1100 to 1200 ° C for 10 to 30 minutes. If the temperature is lower than 1100 ° C, the firing may not be sufficiently performed, and harmful substances such as dioxin may be generated. When the temperature is higher than 1200 ° C, unnecessary energy is required to raise the temperature of the firing furnace.

A system (100) for manufacturing an artificial lightweight aggregate according to another aspect of the present invention includes: a storage tank (111) for storing sludge; A storage tank 2 (112) for storing an inorganic additive; A storage tank 3 (113) for storing the organic additive; A quantitative feeder 1 (121) for feeding the sludge in a quantitative manner; A quantitative feeder 2 (122) for quantitatively feeding the inorganic additive; A quantitative feeder 3 (123) for quantitatively feeding the organic additive; A non-gravity mixer 130 for evenly mixing the sludge, inorganic additive and organic additive supplied by the dosing devices 1 to 3; A continuous kneader 140 for compressing the mixed mixture in the zero-gravity mixer; A kneader 150 for pre-forming the compressed mixture in the continuous kneader; A ventilator (160) for shaping the mixture discharged from the gullet machine into a spherical shape; A surface dryer (170) for drying the spherical shaped body manufactured in the ventilation system before firing; And a firing furnace 180 for firing the spherically shaped body that has been surface-dried in the surface dryer. The air pollution prevention facility may further include an air pollution prevention facility 190 and a wastewater treatment facility 195. The air pollution prevention facility may include a duct for collecting gas and dust generated in the process of producing artificial lightweight aggregate, (191); A dehumidifying tower 192 for treating the gas and dust to prevent odors; A filter / dust collector 193; And a wet scrubbing column 194. FIG. 1 is a process diagram for explaining a system for manufacturing an artificial lightweight aggregate according to an embodiment of the present invention, and FIG. 2 is a process diagram for explaining a system for manufacturing a conventional artificial lightweight aggregate.

The storage tanks 1 to 3 (111 to 113) may be openable and closable for storing sludge, inorganic additive, and organic additive, respectively.

Each of the quantitative feeders 1 to 3 (121 to 123) automatically feeds sludge, inorganic additive, and organic additive to a zero-gravity mixer, and includes a feed pump or a conveyor.

The zero-gravity mixer 130 evenly mixes the sludge, mineral additive, and organic additive supplied by the metered feed devices 1 to 3. The zero-gravity mixer has two main shafts parallel to the Twin Shaft Batch Type Mixer, as can be seen in FIG. 2 (section view) and FIG. 3 (top view) Wherein two arms are fixed and a paddle is mounted on the arm, power is transmitted to the chain drive device by the reducer, the two shafts are rotated at the constant speed in the opposite direction, If the paddle is pushed up to the upper center of the mixing chamber by the rotational force, the effective volume is increased and the zero gravity zone is instantly formed to complete the mixing.

Specifically, a plurality of paddles are designed to over lapping on two twin shafts in a mixing chamber, so that the material is transported by the constant speed rotation to the transport zone and the mixing zone (mixing zone). In a mixed region, a fluidized bed of a zero gravity state is formed irrespective of the particle size, viscosity, and shape of the raw material, thereby completing the mixing in a short time.

The continuous kneader 140 is configured such that a kneading screw is operated by a motor to crush the supplied mixture to remove pores therein, and the number of revolutions is 10 to 20 RPM and the internal residence time is 1 to 5 minutes It is good to keep it. The compressed mixture in the continuous kneader is supplied to the spooler.

It is preferable that the kneader 150 is equipped with a screw conveyor with a braid and the rotation speed is 10 to 20 RPM and the residence time is 2 to 5 minutes. The mixture stoichiometrically transferred to the ventilator.

The ball mill (ball milling machine) 160 has a cylindrical cylinder and a rotating body. The rotating body is rotated by a motor to form a nodule mixture into a spherical shape. The rotating speed is 200 to 400 RPM, Is preferably maintained for 30 to 50 seconds. The ventilation system consists of at least two sets of spherical moldings, and the spherical moldings are transferred to a surface dryer to be described later.

The surface dryer 170 is configured such that the water content of the spherical shaped body is dried to 20 wt% or less at an internal temperature of 100 to 150 ° C, and the residence time is preferably maintained for 10 to 30 minutes. The heat source of the surface dryer is configured to be supplied from the waste heat recovery boiler using the waste heat of the firing furnace. The spherical shaped body discharged from the surface dryer is transferred to the firing furnace.

The firing furnace 180 is composed of a motor for rotating the firing furnace, a firing furnace, an inlet for the spherically shaped body, an outlet for the fired body, and a hot gas outlet. The rotational speed is 1 to 5 RPM, the slope is 1 to 2 degrees, The internal retention time is 10 to 30 minutes, and the internal temperature of the firing furnace is 1100 to 1200 ° C. The heat source of the firing furnace is supplied to the inside through a gas oil or gas burner. The outlet of the firing furnace is composed of a screw conveyor type due to the characteristic of the high-temperature molding after the firing, so that the fired molding is transferred and delayed cooled. In the firing furnace, the spherical shaped body is foamed to form pores, and the outside is fired to produce an artificial lightweight aggregate having a certain surface strength.

The gas and dust collecting duct (DUCT) system 191 collects the gas and dust generated in the process of manufacturing the artificial lightweight aggregate, and the dehumidifying tower 192 processes the collected gas and dust to remove the odor. The filtration and dust collector 193 is filled with calcium hydroxide to purify the noxious gas, and the wet cleaning column 194 is filled with caustic soda to collect harmful substances. Accordingly, the harmful gas is purified through desulfurization oxides, denitrification oxides, dehydrochlorides, dust collecting processes, etc., through a filter and dust collector for dust collection using a Teflon bag and a wet cleaning tower, and is discharged to the outside.

The wastewater treatment facility (195) is configured to biologically and chemically treat water vapor in the course of drying the mixture, water in the operation of the facility, and the like through the agitating tank, the aeration tank, the biological tank, and the like.

1, a system for producing an artificial lightweight aggregate, which is an aspect of the present invention, can be obtained by increasing the ratio of the inorganic additive to the mixture for producing the artificial lightweight aggregate and adding the organic additive thereto, Otherwise, the sludge drying step can be omitted. Therefore, it is possible to reduce the production facilities and enormous energy costs by eliminating the need for the expensive sludge drier (20 in FIG. 2), the conveyor conveyor (26 in FIG. 2) and the auxiliary boiler (80 in FIG. 2) The productivity of the artificial lightweight aggregate which is not only simplified but also lightweight can be increased.

The composition and effect of the present invention will be described in more detail with reference to the following examples and comparative examples. However, this embodiment is intended to explain the present invention more specifically, and the scope of the present invention is not limited to these embodiments.

[Example]

2 kg of sewage sludge having a moisture content of 80% by weight (including 10% by weight of each of organic and inorganic matters), 6.5 kg of an inorganic yellow loam having a water content of 10% by weight and 1.5 kg of an organic additive (sawdust) were mixed, 20% by weight or less, and then charged into a sintering furnace having an inlet temperature of 800 캜, elevated to 1,140 캜 at a heating rate of 20 캜 / min, and fired at 1,140 캜 for 10 minutes to produce an artificial lightweight aggregate.

[Comparative Example 1]

15 kg of sewage sludge having a water content of 80% by weight (including 10% by weight of each organic matter and inorganic matters) was dried to prepare 5 kg of a sludge having a water content of 40% by weight, 3 kg of clay and 2 kg of fly ash as an inorganic additive were mixed, After the molding, it was dried to a water content of 20 wt% or less, then charged into a sintering furnace having an inlet temperature of 800 캜, elevated to 1,140 캜 at a heating rate of 20 캜 / min, and fired at 1,140 캜 for 10 minutes to produce an artificial lightweight aggregate .

[Comparative Example 2]

27 kg of sewage sludge having a moisture content of 80% by weight (including 10% by weight of each organic matter and inorganic matters) was dried to prepare 9 kg of sludge having a water content of 40% by weight, 0.8 kg of clay and 0.2 kg of fly ash as an inorganic additive were mixed, The mixture was sintered at 1,140 ° C at a heating rate of 20 ° C / min and calcined at 1,140 ° C for 10 minutes to obtain an artificial lightweight aggregate. .

[Experimental Example]

Sludge Moisture Consumption Calories

The amounts of heat required to reduce moisture in Examples and Comparative Examples 1 and 2 were measured and are shown in Table 1.

LNG standard fuel cost estimate

The fuel ratios based on the LNG standards of Examples and Comparative Examples 1 and 2 were estimated and are shown in Table 1.

Measurement of artificial lightweight aggregate production

The amounts of artificial lightweight aggregate produced in Examples and Comparative Examples 1 and 2 were measured and reported in Table 1.

As can be seen from Table 1, when the ratio of the inorganic additive to the initial mixture for producing the artificial lightweight aggregate is increased and the organic additive (sawdust) is added, the production amount of the artificial lightweight aggregate is increased without a separate sludge drying process . Therefore, compared to the comparative examples 1 and 2, the amount of heat required to reduce sludge moisture was small, and thus the fuel cost was greatly reduced on the basis of LNG, and the production of artificial lightweight aggregate was the most excellent.

It is to be understood that the present invention is not limited to the above-described embodiments, but various modifications may be made by those skilled in the art without departing from the scope of the present invention.

100: System for manufacturing artificial lightweight aggregate
111: Storage tank 1
112: storage tank 2
113: storage tank 3
121: Quantitative feeder 1
122: Quantitative feeder 2
123: Quantitative feeder 3
130: zero-gravity mixer
140: continuous kneader
150: Dewatering machine
160: My ventilation
170: Surface dryer
180: firing furnace
190: Air Pollution Prevention Facility
195: Wastewater treatment facility

Claims (8)

In an artificial lightweight aggregate utilizing waste,
A sludge having a moisture content of 70 to 80% by weight, an inorganic additive having a water content of 10% by weight or less, and an organic additive,
Wherein the weight ratio of the sludge to the inorganic additive is 1: 1.5 to 5,
Wherein the organic additive is present in an amount of 5 to 20% by weight based on 100% by weight of the entire mixture. The method according to claim 1,
Characterized in that the sludge is sewage sludge or wastewater sludge originating from papermaking and manufacturing factories. The method according to claim 1,
Wherein the inorganic additive is at least one of an ash, a loess, a coal ash, and a stone powder. The method according to claim 1,
Wherein the organic material additive is at least one of sawdust, rice hull, and food waste. A method for producing an artificial lightweight aggregate using waste,
Mixing a sludge having a water content of 70 to 80% by weight, an inorganic additive having a water content of 10% by weight or less and an organic additive to produce a mixture having a moisture content of more than 20% by weight and not more than 40% by weight;
A molding and drying step of preparing the mixture as a spherical shaped body and drying at a moisture content of 20 wt% or less; And
And firing the spherical shaped body at 1100 to 1200 ° C for 10 to 30 minutes. 6. The method of claim 5,
Wherein the weight ratio of the sludge to the inorganic additive in the mixing step is 1: 1.5 to 5, and the organic additive is 5 to 20 wt% based on 100 wt% of the whole mixture. . A reservoir 1 for storing the sludge;
A reservoir 2 for storing an inorganic additive;
A reservoir 3 for storing the organic additive;
A fixed amount supply device 1 for supplying the sludge in a fixed amount;
A fixed amount supply device 2 for supplying the inorganic additive in a fixed amount;
A quantitative feeder 3 for feeding the organic additive in a quantitative manner;
A non-gravity mixer for evenly mixing the sludge, the inorganic additive and the organic additive supplied by the dosing devices 1 to 3;
A continuous kneader for compressing the mixed mixture in the zero-gravity mixer;
A kneader for shaping the mixture compressed in the continuous kneader before molding;
A ventilator for shaping the mixture discharged from the sloop unit into a spherical shape;
A surface dryer for drying the spherical shaped body produced in the ventilator before firing; And
And a sintering furnace for sintering the spherically shaped body that is surface-dried in the surface dryer. 8. The method of claim 7,
Air pollution prevention facilities and wastewater treatment facilities,
The air pollution prevention facility includes a gas and dust collecting duct (DUCT) system for collecting gas and dust generated in the process of producing artificial lightweight aggregate; A dehumidifying tower for treating the gas and dust to remove odors; Filter dust collector; And a wet scrubbing tower. ≪ Desc / Clms Page number 20 >

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