JP6211937B2 - Reusable granulate from wooden waste - Google Patents

Description

  The present invention relates to obtaining a reusable granulated material from woody waste.

  Conventionally, as disclosed in, for example, Japanese Patent Application Publication No. 2006-315890, a reusable granulated material is manufactured from waste (waste material). Of the wastes, woody wastes are usually incinerated, and it is necessary to dispose of the husk and dust generated at that time.

  After the 2011 earthquake, the amount of waste to be treated has increased, and it is difficult to secure a recipient (disposal destination) for wood-based waste husk and soot. Is also required to be used as a raw material for granulation.

  However, since the husk and soot, especially soot, contain a relatively large amount of harmful substances such as lead, it is not possible to make a granulated product with the husk and soot alone. Also, when mixing with other raw materials, it is necessary to optimize the mixing ratio of the burning husk and soot, the type of the other raw materials, and the mixing ratio in light of environmental standards. Furthermore, it is necessary to satisfy environmental standards such as suppression of leaching of harmful substances as a reusable granulated material containing burning husks and dust.

JP 2006-315890 A

  The present invention aims to provide a reusable granulated material containing burning husk and soot generated after incineration of woody waste, and more specifically, it is particularly effective in suppressing the elution of harmful substances including lead. An object is to provide a granulated product that can be reused.

  The present invention granulates a mixture containing burning husk and dust after incineration of woody waste, cement, one or both of bentonite and waste gypsum as an additive, a predetermined insolubilizing agent, and water. A granulated product obtained by processing is provided.

  According to the present invention, when mixing / granulating burning husk and dust with cement as a solidifying material, the caking / particle size can be adjusted by bentonite or waste gypsum as an additive, and further, predetermined insolubilization By using the agent, it is possible to obtain a granulated product capable of suppressing elution of harmful substances such as lead contained mainly in the husk and dust, or hexavalent chromium contained mainly in the cement.

  In one aspect of the present invention, the predetermined insolubilizing agent includes at least one selected from ferrous sulfate, magnesium oxide, and a chelating agent.

  According to one aspect of the present invention, hexavalent chromium contained mainly in cement can be insolubilized by ferrous sulfate, and lead contained mainly in burning husk and dust can be insolubilized by magnesium oxide or a chelating agent. Become.

  In one aspect of the present invention, the waste gypsum includes at least one selected from dihydrate gypsum, hemihydrate gypsum, and anhydrous gypsum.

  According to one aspect of the present invention, the viscosity / particle size of the granulated product is adjusted by using one or more selected from among dihydrate gypsum, hemihydrate gypsum, and anhydrous gypsum as time-consuming gypsum. It becomes possible to adjust according to the use.

  In one embodiment of the present invention, the mixture contains 10 wt% or less and 5 wt% or less of an additive and an insolubilizer, respectively.

  According to one aspect of the present invention, the main ingredients of the combustion husk and soot are treated while maintaining the ratio of the additive and insolubilizing agent necessary for adjusting the viscosity of the granulated product and suppressing the elution of harmful substances. It becomes possible to make the amount above a certain level.

It is a figure which shows the process of manufacturing the granulated material which can be reused from the wooden waste material of this invention. It is a schematic diagram in the case of utilizing the granulated material of this invention as a roadbed material for asphalt pavement.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a process for producing a reusable granulated product according to an embodiment of the present invention. The manufacturing process of FIG. 1 should be carried out, for example, using the equipment of an intermediate treatment facility that recycles construction waste (for example, “Zero Emi Plant” owned by the applicant, Eiwa Kogyo Co., Ltd.). Can do.

  In step S1 of FIG. 1, incineration of wooden waste is performed. The incineration is performed using a predetermined incinerator capable of discriminating and collecting each of the burned husk and soot after incineration. Woody waste includes plant-based waste and wood-based construction waste generated from construction sites. The former includes branches and leaves, thinned wood, sawdust, bark, and straw that come out when pruning trees. In the latter, there are various types and materials such as dismantling scraps of houses, large furniture, and scraps.

  In step S2, the burning husk and soot obtained in step S1 are acquired. The acquisition referred to here includes not only the acquisition of the burning husk and soot obtained from one incinerator in the processing facility, but also the acquisition of the burning husk and soot obtained in a plurality of processing facilities / incinerators.

  In step S3, the raw material (mixture) of the granulated material is prepared by mixing cement as a solidifying material, bentonite or waste gypsum as an additive, and an insolubilizing agent with the burned husk and dust. For example, blast furnace cement B type is used as the cement as the solidifying material. The mixing ratio of cement can be varied in the range of several wt% to several tens wt%, and preferably about 8 to 10 wt%.

The mixing ratio of bentonite or waste gypsum as an additive is 10 wt% or less, preferably about 6 to 7 wt%. The waste gypsum includes one or more selected from dihydrate gypsum (CaSO ₄ · 2H ₂ O), hemihydrate gypsum (CaSO ₄ · 0.5H ₂ O), and anhydrous gypsum (CaSO ₄ ). It can be selected and used in a timely manner. Among these, dihydrate gypsum (CaSO ₄ .2H ₂ O) is most preferable from the viewpoint of recycling unnecessary materials.

  As the insolubilizing agent, a reducing agent such as ferrous sulfate for suppressing elution of hexavalent chromium contained in cement mixed mainly as a solidifying material is included. The insolubilizing agent further includes magnesium oxide or a chelating agent for suppressing elution of heavy metals such as lead mainly contained in the burning husk and dust. For each insolubilizer, the amount of elution from the granulated product after granulation is based on the environmental standards ("Enforcement Regulations of the Soil Contamination Countermeasures Law" (Ministry of the Environment Ordinance No. 29 dated December 26, 2002). ) In a predetermined amount (ratio) so as to be less than. In the environmental standards, for example, the elution amounts of hexavalent chromium and lead are determined to be 0.05 mg / L and 0.01 mg / L in order, and the contents of lead and arsenic are sequentially set to 150 mg / kg and 150 mg / kg. ing.

  The predetermined amount (ratio) of the insolubilizing agent is preferably 5 wt% or less. More specifically, for example, ferrous sulfate, magnesium oxide, and a chelating agent are in the order of 0. It is about 5-1.0 wt%, 2-5 wt%, and 0.2-1.0 wt%. It was found that when each additive was added in these proportions (ranges), the above environmental standards could be satisfied (below).

  In step S4, while adding an appropriate amount (in the range of 10 to 20 wt%) of water to the mixture obtained in the mixing step S3, the mixture is granulated and a granulated product is generated. The particle size of the granulated material changes depending on the rotation speed, rotation time, etc. of the blades of the granulator, and the proportion of the granulated material having a large particle size can be increased by increasing the rotation time (ie, granulation time). it can. The particle size of the granulated product is set as appropriate according to the intended use of the granulated product.

  In step S5, the granulated material is cured. Curing is important for improving the strength of the granulated product, and is also important for reducing the amount of elution of hexavalent chromium and lead, as well as arsenic and fluorine. In an experiment by the present inventor, it has been found that by securing a curing period of at least 4 days, for example, about 5 days, various amounts of elution can be reduced below the respective environmental standard values. The curing period is not an essential requirement in the production method of the granulated product of the present invention, and can be arbitrarily selected according to the use of the granulated product.

  In step S6, quality control of the generated granulated material is performed. Quality control inspects / confirms whether the granulated product meets specifications (grain size, environmental standards, etc.) suitable for the application. The granulated material that has passed the inspection is, for example, mixed with recycled concrete (RC) 40 at a predetermined ratio and reused as a roadbed material or a soil material for land reclamation.

  FIG. 2 is a schematic diagram when the granulated product of the present invention is used as a roadbed material for asphalt pavement. The roadbed material for asphalt pavement means the roadbed material 20 disposed under the surface layer / base layer 10 containing asphalt in the asphalt pavement, and particularly means a material for the lower layer roadbed of the roadbed material. As shown in FIG. 2, the granulated material is mixed as a roadbed material 20 so as to fill a space between the RC 40 (22).

  A plurality of samples (granulated products) were actually manufactured by changing the mixing ratio, and quality evaluation was performed. When setting the mixing ratio, the content of lead contained in the dust is particularly weight. As an example, when using soot dust with a lead content of 1900 mg / kg and a burning husk of 50 mg / kg as the raw material, if the soot dust is 5 wt% and the burning husk is 95 wt%, the lead content in the mixture of soot dust and husk is about 140 mg / kg The environmental standard is 150 mg / kg or less. This mixed raw material is mixed with cement, dihydrate gypsum as an additive, ferrous sulfate as an insolubilizer, and a chelating agent or magnesium oxide to suppress the elution amount. As a result, as an example, in a granulated product manufactured using a mixture mixed at a mixing ratio (wt%) shown in the following two tables, harmful substances (cadmium, hexavalent chromium, It was confirmed that the amount of elution of cyan, lead, arsenic, fluorine, etc.) can be kept below the value determined by environmental standards.

<Mixing ratio (wt%)>

  Embodiments of the present invention have been described with reference to the drawings. However, the present invention is not limited to these embodiments. The present invention can be implemented in variously modified, modified, and modified embodiments based on the knowledge of those skilled in the art without departing from the spirit of the present invention.

Claims (6)

  It is obtained by granulating a mixture containing burning husks and dust after incineration of woody waste, cement, one or both of bentonite and waste gypsum as additives, a predetermined insolubilizing agent, and water. Granulated product.   The granulated product according to claim 1, wherein the predetermined insolubilizing agent includes at least one selected from ferrous sulfate, magnesium oxide, and a chelating agent.   The granulated product according to claim 1 or 2, wherein the waste gypsum includes at least one selected from dihydrate gypsum, hemihydrate gypsum, and anhydrous gypsum.   The granulated product according to any one of claims 1 to 3, wherein the mixture contains 10 wt% or less and 5 wt% or less of the additive and the insolubilizer, respectively.   The granulated product has an elution amount of lead or hexavalent chromium of less than 0.01 mg / liter, or less than 0.05 mg / liter, and a lead or arsenic content of less than 150 mg / kg, or less than 150 mg / kg. The granulated product according to any one of claims 2 to 4, wherein   A roadbed material or a soil material comprising the granulated product according to any one of claims 1 to 5.

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