CN113232116A - Method for manufacturing ecological plate by utilizing polluted soil restoration plants - Google Patents

Abstract

A method for manufacturing ecological plates by utilizing contaminated soil restoration plants comprises the steps of harvesting giant reed which is a heavy metal contaminated soil restoration plant, removing blades after the giant reed is mature, cutting stems into lengths of 2-4cm, screening, drying and crushing, fully and uniformly stirring crushed materials and adhesives in a glue mixer, enabling the adding proportion of surface and core layer adhesives to be 3.5-5% and 3-4% respectively, forming a rough board through processes of paving, detecting, pre-pressing, hot-pressing and the like, removing solidified layers from the rough board through coarse sand and fine sand, obtaining the ecological plates, and producing 1 cubic ecological plates by 1.2 tons of giant reed stems. The giant reed restores the heavy metal contaminated soil, and the restored giant reed stalks can be used as the raw materials of the plates to realize comprehensive utilization while absorbing and removing the heavy metals in the soil. The invention provides an industrial utilization approach for safe resource utilization of heavy metal contaminated soil remediation plants in China and solving the problem that potential secondary pollution is easily caused by improper treatment of the plants after remediation.

Description

Method for manufacturing ecological plate by utilizing polluted soil restoration plants

Technical Field

The invention belongs to the field of comprehensive utilization of polluted soil restoration plants, and particularly relates to a method for manufacturing an ecological plate by utilizing the polluted soil restoration plants.

Background

The giant reed is a perennial root herbaceous plant belonging to the genus Arundo belonging to the family Gramineae, is native to Europe, is fond of warm, light, moisture and cold resistance, is widely introduced and cultivated in wetland gardens of China, is distributed in regions such as Jiangsu, Zhejiang, Hunan, Shandong, Guangxi and the like, is a perennial, clustered and evergreen plant, can grow in poor soil or polluted regions, and has the characteristics of large biomass, developed root system, strong adaptability and the like. Researches show that the arundo donax linn has large enrichment amount and good tolerance to heavy metals Cd and Hg, and can absorb and accumulate certain types of heavy metal ions by planting the arundo donax linn in areas with serious heavy metal pollution, so that the arundo donax linn has an effective effect on soil remediation. Researches show that the giant reed shows good tolerance when growing in the soil highly polluted by Cd, Ni, Cu, Pb, Zn, Hg and Cr 7 heavy metals, has strong enrichment capacity on the heavy metals and has a certain repairing effect on the polluted soil. The giant reed biomass is large, the growth power is vigorous, the capacity of absorbing heavy metals from soil is strong, the per-year acre yield is 3-4 tons (dry weight), the average mercury content in the giant reed plants is 4.46 +/-1.40 mg/kg, the heavy metal Hg can be extracted from the soil every year and reaches 11.63-18.47 g/acre, and meanwhile, the heavy metals Cd, Cr, As and Pb are absorbed, so that the giant reed has a good repairing effect on the soil polluted by single or mixed heavy metals, and the giant reed is widely applied to the aspect of plant ecological repairing. The giant reed can be used as a heavy metal polluted soil restoration plant, is a pioneer plant for restoring vegetation of wasteland and preventing sand and fixing soil, and has important ecological value.

Engineering application of phytoremediation techniques can produce a large number of heavy metal-containing remediation plants, which, if improperly disposed, can cause secondary pollution. Therefore, how to scientifically, reasonably and environmentally-friendly treat the heavy metal-containing repair plants generated in the repair process becomes one of the key scientific problems which need to be solved urgently by popularization and application of the plant repair technology. At present, most heavy metal polluted soil restoration plants adopt treatment methods such as an incineration method, a composting method, a compression landfill method, a high-temperature decomposition method and the like, and the incineration and high-temperature decomposition methods have the defects that volatile heavy metals are easy to volatilize and pollute air due to high temperature, the treatment cost is high, and the popularization and the application are difficult; the difficulty of removing heavy metals in plants by a composting method is high, and the heavy metals are easy to pollute the soil again along with nutrients; the compressed landfill method occupies a large soil space, has a large ecological risk to underground water and soil, and has a risk of pollution migration. Based on the principles of reduction, harmlessness and recycling, a technology for safely and effectively recycling the repaired plants, which is more economical and feasible, needs to be developed.

As a big country with demand for artificial boards in China, the existing board manufacturing enterprises use various agricultural and forestry wastes such as straws, wheat straws, reeds, cotton stalks, fruit branches, bamboos and the like as main raw materials, solve the problem of shortage of wood resources and produce the artificial boards. Arundo donax is a perennial herbaceous lignocellulosic plant rich in a large amount of cellulose and lignin. The content of lignin and cellulose of the Arundo donax stems is the highest, and respectively reaches 20.5-30.2% and 38.3-51.1%, and the Arundo donax stems are high-quality raw materials for producing artificial boards. However, no report has been reported so far for producing safe and environment-friendly ecological boards by using giant reed as a raw material after remediation of heavy metal contaminated soil. The invention aims to prepare an ecological plate with high economic added value by using the giant reed subjected to heavy metal contaminated soil remediation, improve the comprehensive utilization rate of the remediation plant resource, form a soil remediation closed industrial chain with front-end contaminated soil phytoremediation and rear-end remediation plant resource safe utilization, and build a new ecological remediation development mode of plants integrating ecological treatment, ecological poverty alleviation and ecological industry.

Disclosure of Invention

The technical problem to be solved is as follows: in order to effectively utilize the arundo donax stems for restoring the soil polluted by the overweight metal, the invention provides a method for manufacturing an ecological plate by utilizing the polluted soil restoration plants.

The technical scheme is as follows: the method for manufacturing the ecological plate by utilizing the polluted soil restoration plants comprises the following steps: 1) planting Arundo donax in heavy metal contaminated soil according to a conventional planting method, keeping daily field management consistent with local planting habits, and harvesting in 11-12 months per year for later use; 2) cutting the raw materials into 2-4cm long pieces by a chopper and then storing the cut pieces; 3) drying the stored raw materials, further crushing to obtain fine particle materials, winnowing, screening to be qualified, respectively storing the fine particle materials in a surface layer material bin and a core layer material bin, wherein the size of the surface layer material is 0.15-1.00mm, the size of the core layer material is 1.7-30mm, and returning the screened coarse materials to the crusher to continue crushing; 4) the surface and core layer dry wood shavings are metered and then continuously and uniformly enter a surface and core layer wood shavings glue mixer, adhesive is injected at the same time, the adding proportion of the adhesive to the surface and core layers is 3.5-5 wt.% and 3-4 wt.%, and the adhesive solution is uniformly wrapped on the surfaces of the wood shavings by mutual friction in the glue mixer to form surface and core layer glue-applying wood shavings; 5) delivering the surface layer and the core layer glue application wood shavings into a measuring bin of a paving machine, delivering the wood shavings into a high-precision paving machine for paving, wherein the mass ratio of materials of the surface layer to the core layer is 5:5-3:7, delivering the wood shavings into a continuous prepressing machine by a plate blank conveyor for prepressing at 0.2-0.5MPa, and finally delivering the wood shavings into a continuous flat-pressing hot press for hot pressing, wherein the high-pressure section is 3-4MPa, and 210 and 220 ℃; the medium pressure section is 2.5-0.8MPa and is at 220-230 ℃; the low pressure section is 0.6-0.2MPa and 185-195 ℃; pressing the plate blank into a rough plate with the density and thickness required by the process, cutting and cooling the rough plate, and then entering an intermediate storage for stacking and curing; 6) after stacking for 2 days and natural cooling, the plates are sent to a sanding line by a rail car, pre-cured layers of the plates are removed after coarse sand and fine sand are carried out on the plates to ensure the requirement of thickness tolerance, the sanded plates are cut to a specified length through trimming and cross cutting, and finally the plates are stacked into plate stacks with the height of 1.2 meters after inspection and grading and are sent to a warehouse by a forklift.

The heavy metal contaminated soil is neutral and alkaline, and the contents of Cd, Hg, Pb, Cr and As in the soil are respectively 0.55-1.72, 8.61-36.10, 39.00-53.30, 56.50-95.30 and 7.69-15.90 mg/kg.

The giant reed adopts two seedling raising planting modes of rhizome cutting and stem cutting, the planting density is 80cm multiplied by 80cm, and the giant reed is harvested 11-12 months per year according to a field daily management method of conventional planting.

Has the advantages that: the invention provides a feasible industrialized engineering approach for solving the problem of resource utilization of the soil heavy metal pollution remediation plant Arundo donax Linn. The content of heavy metal Hg extracted from the giant reed in the year is as follows: 11.63-18.47 g/mu, the harvested giant reed stems are difficult to treat, occupy more resources and have higher cost, and the giant reed stems absorbing heavy metals are put forward to be used for producing artificial boards for the first time. As can be seen from Table 2, the pure Arundo donax ecological board has low density, small glue application amount, and various physical and mechanical indexes such as static bending strength, elastic modulus, internal combination, surface combination, board edge nail holding force, board nail holding force, 2h water absorption expansion rate and the like which are all larger than those of a P2 type shaving board (GB/T4897-2015 shaving board), and meets the standard requirements of common furniture manufacture.

Drawings

Fig. 1 is a real figure of a giant reed base plate.

Detailed Description

The board making step of the giant reed stalks comprises: giant reed → cutting → crushing → drying → sieving (dividing into surface layer material and core layer material) → sorting → sizing → paving → prepressing → hot pressing → cutting → cooling → stacking → sanding → sawing → sorting → packing and warehousing.

Cutting: 20-40mm Arundo donax stems;

and (3) drying: the water content is controlled between 2 percent and 4 percent;

screening: 0.15-1mm of surface material; 1.7-30mm of core layer material;

sorting: removing big materials, stones and the like;

sizing: skin layer 3.5 wt.% to 5.0 wt.%; core 3.0 wt.% to 4.0 wt.%;

paving: the mass ratio of the surface layer to the core layer is 5:5-3:7, the water content of the surface layer is 15-19 wt.%, and the water content of the core layer is 4-5 wt.%;

cutting: cutting into 8 × 16 ruler or other large size plate;

sanding: sanding according to different thicknesses;

sawing: sawing into 4 × 8 ruler or other sizes;

sorting: and removing unqualified products.

Example 1

1) Before planting, carrying out rotary tillage on soil, wherein the depth of a plough layer is 20-30 cm, furrowing is required before planting, the width of a furrow surface is 2-4 m, the width of a furrow is 20-30 cm, the depth of the furrow is 20cm, and the depth of a surrounding furrow is 30-40 cm. 50-100 kg/mu of compound fertilizer and 1000-1500 kg/mu of organic fertilizer are used as base fertilizer and applied before planting and rotary tillage. Transplanting the giant reed seedlings by adopting an artificial cuttage planting mode. And transplanting the seedlings to heavy metal contaminated soil after 6-8 true leaves grow. And (4) removing the tops of the seedling leaves if the leaves are too long during transplanting, and keeping the leaves at the length of 4-5 cm. When the seedlings are transplanted in the field, the plant spacing and the row spacing are respectively 60-80 cm and 60-80 cm, water is immediately irrigated after the seedlings are transplanted, and the soil is kept moist within 10-15 days after the seedlings are transplanted. When the plant height is 20-40 cm, intertilling and weeding for 2-3 times. After the giant reed seedlings are planted for 30-45 days, the height of the seedlings is 20-30 cm, 5-10 kg/mu of urea is applied, tillering and strong seedlings are promoted, the seedlings can be topdressed at the roots among the seedlings, and the seedlings are harvested for later use in 11-12 months every year. In order to carry out continuous cropping for many years, stubble is left for 5-10 cm after harvesting; 2) cutting the raw materials into 2-4cm long pieces by a chopper and then storing the cut pieces; 3) drying the stored raw materials, further crushing to obtain fine particle materials, winnowing, screening to obtain qualified materials, respectively storing the qualified materials in a surface layer material bin and a core layer material bin (a hammer type crusher is adopted for crushing, the aperture of a screen mesh is 4-8mm, the materials are dried and screened into a surface layer material and a core layer material, the size of the surface layer material is 0.15-1.00mm, and the size of the core layer material is 1.7-30 mm), and returning the screened coarse materials to the crusher for continuous crushing; 4) the surface and core layer dry wood shavings are metered and then continuously and uniformly enter a surface and core layer wood shavings glue mixer, adhesive is injected at the same time, the adding proportion of the adhesive to the surface and core layers is 3.5-5 wt.% and 3-4 wt.%, and the adhesive solution is uniformly wrapped on the surfaces of the wood shavings by mutual friction in the glue mixer to form surface and core layer glue-applying wood shavings; 5) the surface and core layer glue applying shavings are input into a measuring bin of a paving machine, then are sent into a high-precision paving machine for paving, and are sent into a continuous prepressing machine by a slab conveyer for prepressing, wherein the prepressing is to perform preliminary compaction on the paved slabs, mainly plays a role in removing air and increasing the strength of the slabs, is beneficial to entering a continuous hot press, and has the prepressing pressure of 0.2-0.5 MPa; finally, the mixture is sent into a continuous flat-pressing hot press for hot pressing; the hot pressing parameters mainly comprise pressure and temperature:

high pressure section	Medium pressure section	Low pressure section
			3-4MPa	2.5-0.8MPa	0.6-0.2MPa
210-220℃	220-230℃	185-195℃

Pressing the plate blank into a rough plate with the density and thickness required by the process, cutting and cooling the rough plate, and then entering an intermediate storage for stacking and curing; 6) after stacking for 2 days and natural cooling, the plates are sent to a sanding line by a rail car, pre-cured layers of the plates are removed after coarse sand and fine sand are carried out on the plates to ensure the requirement of thickness tolerance, the sanded plates are cut to a specified length through trimming and cross cutting, and finally the plates are stacked into plate stacks with the height of 1.2 meters after inspection and grading and are sent to a warehouse by a forklift.

TABLE 2 Giantreed-based ecological Board basic physical and mechanical Properties data

The mercury content in the artificial board made of pure arundo donax stems is 17.01 +/-0.82 mg/kg, and meets the limit requirement of national standard harmful substance limit in interior decoration and finishing material wood furniture (GB 18584-. 1.2 tons of pure giant reed stalks can produce 1 cubic plate, and the market price is about 2500 yuan. 3-4 arundo donax stems can be produced in one mu of land, and the economic benefit of 6000-8000 yuan can be produced. Therefore, the method for manufacturing the ecological plate by utilizing the polluted soil restoration plants not only reduces the restoration cost of the heavy metal polluted soil, but also solves the problem of secondary pollution caused by improper disposal of the restoration plants, and can really realize the aim of turning waste into wealth and realizing the integrated development of ecological restoration and ecological industry.

Claims (3)

1. The method for manufacturing the ecological plate by utilizing the polluted soil restoration plants is characterized by comprising the following steps: 1) planting Arundo donax in heavy metal contaminated soil according to a conventional planting method, keeping daily field management consistent with local planting habits, and harvesting in 11-12 months per year for later use; 2) cutting the raw materials into 2-4cm long pieces by a chopper and then storing the cut pieces; 3) drying the stored raw materials, further crushing to obtain fine particle materials, winnowing, screening to be qualified, respectively storing the fine particle materials in a surface layer material bin and a core layer material bin, wherein the size of the surface layer material is 0.15-1.00mm, the size of the core layer material is 1.7-30mm, and returning the screened coarse materials to the crusher to continue crushing; 4) the surface and core layer dry wood shavings are metered and then continuously and uniformly enter a surface and core layer wood shavings glue mixer, adhesive is injected at the same time, the adding proportion of the adhesive to the surface and core layers is 3.5-5 wt.% and 3-4 wt.%, and the adhesive solution is uniformly wrapped on the surfaces of the wood shavings by mutual friction in the glue mixer to form surface and core layer glue-applying wood shavings; 5) delivering the surface layer and the core layer glue application wood shavings into a measuring bin of a paving machine, delivering the wood shavings into a high-precision paving machine for paving, wherein the mass ratio of materials of the surface layer to the core layer is 5:5-3:7, delivering the wood shavings into a continuous prepressing machine by a plate blank conveyor for prepressing at 0.2-0.5MPa, and finally delivering the wood shavings into a continuous flat-pressing hot press for hot pressing, wherein the high-pressure section is 3-4MPa, and 210 and 220 ℃; the medium pressure section is 2.5-0.8MPa and is at 220-230 ℃; the low pressure section is 0.6-0.2MPa and 185-195 ℃; pressing the plate blank into a rough plate with the density and thickness required by the process, cutting and cooling the rough plate, and then entering an intermediate storage for stacking and curing; 6) after stacking for 2 days and natural cooling, the plates are sent to a sanding line by a rail car, pre-cured layers of the plates are removed after coarse sand and fine sand are carried out on the plates to ensure the requirement of thickness tolerance, the sanded plates are cut to a specified length through trimming and cross cutting, and finally the plates are stacked into plate stacks with the height of 1.2 meters after inspection and grading and are sent to a warehouse by a forklift.

2. The method for manufacturing the ecological plate by using the polluted soil restoration plants according to claim 1, wherein the heavy metal polluted soil is neutral and alkalescent, and the contents of Cd, Hg, Pb, Cr and As in the soil are respectively 0.55-1.72, 8.61-36.10, 39.00-53.30, 56.50-95.30 and 7.69-15.90 mg/kg.

3. The method for manufacturing the ecological plate by utilizing the polluted soil restoration plants according to claim 1, wherein the arundo donax linn adopts two seedling raising planting modes of rhizome cutting and stem cutting, the planting density is 80cm x 80cm, and the arundo donax linn is harvested 11-12 months per year according to a field daily management method of conventional planting.

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