JP4005932B2 - Pyrolysis treatment method of waste wood - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
TECHNICAL FIELD The present invention relates to a method for thermally decomposing waste wood contained in construction waste, and in particular, recycles wood waste containing harmful arsenic (As) by carrying out pyrolysis without environmental impact. The present invention relates to a thermal decomposition method.
[0002]
[Prior art]
In recent years, construction waste accounts for about 20% of the total industrial waste and about 40% of the final disposal amount. Furthermore, construction waste accounts for 90% of illegal dumping of industrial waste.
On the other hand, the remaining years of the final disposal site are less than 3 years and are becoming tight.
Furthermore, with the renewal period of buildings rapidly increasing since the Showa 40s, it is expected that the amount of dismantling will increase rapidly in the future.
Recycling construction waste, which continues to increase, is an important issue in global environmental problems.
However, in the past, CCA wood in which CCA (referred to as chromium (Cr), copper (Cu) and arsenic (As) compound wood preservatives) was injected into wood for preserving and preventing ants, especially among wood wastes. As for system wastes, harmful arsenic gases are generated when incinerated, and therefore, landfill treatment has been performed, and reuse as resources has not been made sufficiently.
[0003]
In addition, a system that appropriately consumes a large amount for each material selected from a large amount of construction waste has not been constructed.
Concerning the sorting method of construction waste, for example, in Japanese Patent Application Laid-Open No. 7-290000, after spraying the construction waste containing earth and sand and combustible material to sort out large combustible material, the remaining waste material is dried. A method for sorting earth and sand and small combustibles by subjecting them to a sorting step is disclosed.
However, this technology only proposes a method for sorting construction waste, and a reuse method as a specific resource and a treatment method according to its use have not been studied.
Japanese Patent Application Laid-Open No. 2002-20771 discloses a method in which the pulverized particle size of waste wood is adjusted to increase the combustibility and air transportability and to be charged into a blast furnace.
However, this technology discloses conditions for enhancing combustibility and air transportability when waste wood is charged into a blast furnace, and is a specific method for treating environmentally hazardous substances such as chromium, copper, and arsenic. There was nothing to be considered about.
[0004]
[Patent Document 1]
JP-A-7-290000 [Patent Document 2]
Japanese Patent Laid-Open No. 2002-20771
[Problems to be solved by the invention]
The present invention solves the problems of the prior art as described above, and appropriately treats CCA wood wastes injected with Cr, Cu and As to produce wood wastes containing harmful arsenic (As). It is an object of the present invention to provide a thermal decomposition processing method for recycling resources by performing thermal decomposition processing without environmental impact.
[0006]
[Means for Solving the Problems]
As a result of intensive studies in order to solve the above-mentioned problems, the inventors have conducted a thermal decomposition treatment by supplying a sulfur-containing material together with a CCA wood-based waste material into which Cr, Cu and As have been injected, The present invention provides a thermal decomposition method for recycling a waste material containing harmful arsenic (As) by carrying out thermal decomposition treatment without environmental impact, and the gist of the invention is as follows. It is the following contents as described in.
(1) In the method of thermally decomposing waste wood contained in construction waste, a sulfur-containing material is supplied and pyrolyzed together with CCA wood waste injected with Cr, Cu and As. Thermal decomposition method for waste wood.
(2) The method for thermally decomposing waste wood according to (1), further comprising supplying a substance containing iron and / or copper to thermally decompose.
(3) The thermal decomposition treatment method of waste wood according to (1) or (2), wherein the thermal decomposition treatment temperature is 500 to 760 ° C.
(4) The method for pyrolyzing waste wood according to any one of (1) to (3), wherein the residue after pyrolysis is used as an auxiliary material for copper refining.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described in detail with reference to FIG.
FIG. 1 is a flowchart showing a method for thermally decomposing waste wood according to the present invention.
In the present invention, a sulfur-containing material is supplied and pyrolyzed together with CCA wood-based waste injected with Cr, Cu and As.
Here, construction waste refers to industrial waste including wood-based waste generated from construction and demolition sites such as buildings and houses, waste generated when pruning roadside trees (pruning material), etc. , CCA wood waste is about 0.1% by mass of CCA (chromium (Cr), copper (Cu) and arsenic (As) compound wood preservatives) in total for preserving and preventing ants. Wood waste.
In the present invention, the type of sulfur-containing material supplied together with the CCA wood-based waste is not limited, but rubber, tires, and the like generated as waste are preferable from the viewpoint of easy availability.
[0008]
Sulfur (S) is fixed in combination with arsenic (As) and has the property of not being transferred to gas or oil generated during thermal decomposition. It is possible to provide clean gas or oil that does not contain (As).
In addition to the sulfur-containing material, it is preferable to further thermally decompose by supplying a material containing iron and / or copper.
Iron (Fe), like sulfur (S), has the property of immobilizing arsenic (As), and copper (Cu) is a thermodynamically stable element that combines with arsenic (As). In addition, when the pyrolyzed residue is used as an auxiliary material in the copper refining process, a higher copper (Cu) content is preferable.
[0009]
As a substance containing iron, for example, a tire contains both iron (Fe) as a steel cord and sulfur (S) in rubber, which is preferable.
Moreover, since a large amount of iron powder is contained in the steelmaking dust generated in the iron making process, it may be used.
As a substance containing copper, it is preferable to use a copper wire contained in construction waste or a scrapped vehicle from the viewpoint of easy availability.
The thermal decomposition treatment temperature is preferably 500 to 760 ° C.
If it is less than 500 ° C, the generation ratio of gas and oil is low because the volatile components in the waste are not sufficiently evaporated, and if it exceeds 760 ° C, it exceeds the service temperature of heating equipment such as a steel external heating rotary kiln. Because it will end up.
The clean gas and oil substantially free of arsenic (As) generated by the thermal decomposition treatment method of waste wood according to the present invention is reformed and then used for iron making processes such as power plants in steelworks and waste disposal. It can be used as a necessary fuel.
[0010]
Further, since the pyrolyzed residue contains Cr, Cu, As, it is preferably used as an auxiliary material for copper refining.
Since copper ore originally contains trace amounts of arsenic (As), arsenic (As) contained in the auxiliary raw materials is contained in the copper ore in order to remove arsenic (As) during the copper refining process. This is because they can be separated together with the contained arsenic. In addition, according to the present invention, the CCA wood-based waste containing Cr, Cu, As is used as it is in the copper refining process as it is, and the purity of Cu is high and as a reduced raw material. Since it can be used, it is easy to handle and logistics costs can be reduced.
[0011]
【Example】
Using an externally heated rotary kiln with an inner diameter of 800 mm and a length of 6000 mm, cut tires and steelmaking dust were supplied under the following conditions to conduct thermal decomposition experiments on CCA wood waste.
<Example-1>
Thermal decomposition temperature 600 ℃
Pyrolysis time 30min
Material mix CCA-containing wood 1kg of cut tires per 1kg
As immobilization rate 90%
<Example-2>
Thermal decomposition temperature 600 ℃
Pyrolysis time 30min
Raw material mix CCA containing wood 0.14kg of cut tires per 1kg and 0.14kg of steelmaking dust
As immobilization rate 98%
<Example-3>
Thermal decomposition temperature 600 ℃
Pyrolysis time 30min
Material mix CCA-containing wood 1 kg of cut tires per 1 kg
As immobilization rate 98%
Here, the As immobilization rate is defined as the ratio of the As content contained in the residue after pyrolysis to the total As content in the thermal decomposition treatment object. As this value is closer to 100, As does not shift to gas or oil, which means that processing with a small environmental load is realized.
[0012]
<Experimental result>
As a result of this experiment, in Example-1 in which 0.14 kg of cut tire was supplied per 1 kg of CCA-containing wood, the arsenic (As) immobilization rate was 90%, and 0.14 kg of cut tire and 0.14 kg of steelmaking dust were supplied. In Example 2 and Example 3 in which 2 kg of cut tires were supplied, the arsenic (As) immobilization rate was 98%.
That is, in the gas and oil generated by thermal decomposition, 10% of arsenic (As) in the CCA-containing wood is used in Example 1, and arsenic (As) in the CCA-containing wood is used in Examples 2 and 3. Only 2%.
Therefore, according to the present invention, the immobilization rate can be remarkably increased as compared with the immobilization rate of about 50% of arsenic (As) when pyrolyzing without supplying a sulfur-containing substance. It was confirmed that clean gas and oil not containing (As) can be provided.
[0013]
【The invention's effect】
According to the present invention, by supplying a sulfur-containing substance together with CCA wood waste into which Cr, Cu and As are injected, and performing a thermal decomposition treatment, the wood waste containing harmful arsenic (As) is obtained. An industrially useful remarkable effect can be provided, for example, by providing a thermal decomposition method for recycling by performing thermal decomposition treatment without environmental load.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a flowchart showing a method for thermally decomposing waste wood according to the present invention.

Claims (4)

In a method for thermally decomposing waste wood contained in construction waste, the waste wood is characterized in that it is pyrolyzed by supplying a sulfur-containing material together with CCA wood waste injected with Cr, Cu and As. Thermal decomposition method. The method for pyrolyzing waste wood according to claim 1, further comprising supplying a substance containing iron and / or copper for pyrolysis. The thermal decomposition treatment method for waste wood according to claim 1 or 2, wherein the thermal decomposition treatment temperature is 500 to 760 ° C. The method for pyrolyzing waste wood according to any one of claims 1 to 3, wherein the residue after pyrolysis is used as an auxiliary material for copper refining.

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