Method for preparing granular soil from metal processing cooling wastewater and yellow soil

Abstract

The invention discloses a method for preparing granular soil from metal processing cooling wastewater and yellow soil, and relates to the technical field of resource reutilization. Mixing and stirring the precipitated wastewater and yellow soil to form yellow mud; pouring the yellow mud into a sintering box, feeding into a heating furnace, and sintering into blocks; and crushing the sintered body to obtain the granular soil. According to the method for preparing the granular soil by utilizing the metal processing cooling wastewater and the yellow soil, the raw material of the granular soil is prepared by converting the steel pipe penetrating cooling wastewater and the yellow soil, and the wastewater is recycled, so that the wastewater treatment cost is remarkably reduced, and economic benefits are created for enterprises; and the prepared granular soil has excellent water storage, drainage and air permeability, has far-reaching influence on soil improvement and plant growth, and has a very wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of resource recycling, and specifically to a method for preparing granular soil by using metal processing cooling wastewater and yellow clay. Background Art

[0002] When steel pipes are processed by the hot piercing process, cooling is an essential step, and a large amount of cooling wastewater is generated during this process. These wastewaters are rich in iron elements, carbon elements, and other trace mineral elements, which have a significant promoting effect on plant growth. However, traditional wastewater treatment methods are not only costly but also often ignore the potential value of these beneficial elements in the wastewater.

[0003] In horticultural practice, soil improvement is the core link to improve the growth quality and yield of plants. Akadama soil, as an ideal improvement material, with its unique porous structure, has excellent water storage, drainage, and ventilation properties, and can slowly release mineral nutrients, providing a balanced growth environment for plant roots, so it is highly regarded in the high-end horticultural field. However, its wide application faces significant constraints: on the one hand, Akadama soil relies on the mining of specific volcanic rock ore layers, and multiple processes such as crushing, screening, and calcination are required during the processing, resulting in high production costs; on the other hand, its market price fluctuates with the transportation distance and resource scarcity, further restricting the use of small and medium-sized horticultural projects. In contrast, although yellow clay is low-cost and easy to obtain, it has obvious defects due to its high clay content. It is prone to hardening and caking in the wet state, hindering water permeability and air permeability, shrinking and cracking after drying, damaging the roots, and having a low mineral content, making it difficult to meet the comprehensive requirements of most plants for soil physical structure and fertility.

[0004] Therefore, it is necessary to propose a method for preparing granular soil by using metal processing cooling wastewater and yellow clay to solve the above problems. Summary of the Invention

[0005] (I) Technical Problems to be Solved The purpose of the present invention is to provide a method for preparing granular soil by using metal processing cooling wastewater and yellow clay to solve the problems raised in the above background art.

[0006] (II) Technical Solutions To achieve the above objectives, the present invention is realized through the following technical solutions: A method for preparing granular soil by using metal processing cooling wastewater and yellow clay, comprising the following steps: S1. Precipitate the steel pipe piercing cooling wastewater; S2. Mix and stir the precipitated wastewater with yellow clay to form yellow mud; S3. Pour the yellow mud into a sintering box and send it into a heating furnace to sinter into blocks; S4. Crush the sintered body to obtain granular soil.

[0007] Preferably, step S1 further includes adjusting the pH of the wastewater to 6 - 6.5.

[0008] Preferably, in step S3, the thickness of the yellow mud slurry laid in the sintering box is 4 - 8 cm.

[0009] Preferably, the sintering process in step S3 adopts segmented temperature control: The first stage: heat up to 200 - 300 °C, keep warm for 30 - 60 min, and discharge the bound water; The second stage: heat up to 750 - 850 °C, keep warm for 1 - 2 h, and sinter into shape.

[0010] Preferably, the heating rate in the first stage is controlled at 5 - 8 °C / min, and the heating rate in the second stage is controlled at 8 - 10 °C / min.

[0011] Preferably, the heating rate in the first stage is controlled at 25 - 35 °C / min, and the heating rate in the second stage is controlled at 30 - 40 °C / min.

[0012] Preferably, the granular soil obtained in step S4 is sieved to obtain granular soil with different particle size gradings.

[0013] As another aspect of the present application, the present application also provides a granular soil prepared by the method for preparing granular soil as described above.

[0014] (III) Beneficial effects The present invention provides a method for preparing granular soil by using metal processing cooling wastewater and yellow clay soil, and has the following beneficial effects: By using the steel pipe cooling wastewater conversion and yellow clay soil as raw materials for preparing granular soil, through the reuse of wastewater, not only the wastewater treatment cost is significantly reduced, creating economic benefits for enterprises, but also the prepared granular soil has excellent water storage, drainage and air permeability performance, has a profound impact on soil improvement and plant growth, and has a very broad application prospect. Specific embodiments

[0015] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0016] Example 1 A method for preparing granular soil by using metal processing cooling wastewater and yellow clay soil, including the following steps: S1. Precipitation of steel pipe cooling wastewater First, collect the cooling wastewater generated during the steel annealing process and introduce the wastewater into the sedimentation tank. In the sedimentation tank, heavier solid particles will gradually settle to the bottom under the action of gravity, forming a sludge layer, while lighter suspended solids and dissolved substances may remain in the supernatant. Through a period of standing, preliminary purification of the wastewater can be achieved.

[0017] During this process, add hydrochloric acid to the wastewater to adjust the pH within the range of 6 - 6.5 to make it weakly acidic, promote the dissolution of iron, and prevent the formation of iron hydroxide precipitation.

[0018] S2. Prepare yellow mud slurry Mix the wastewater treated by sedimentation with yellow clay to form yellow mud slurry with a certain viscosity and fluidity. To ensure uniform mixing, fully stir the yellow mud slurry through a stirring device so that the components in the wastewater can fully contact and combine with the yellow clay.

[0019] Among them, the yellow clay needs to be screened before use to remove impurities such as stones and tree roots. The yellow clay used is the yellow clay excavated during engineering construction, and its waste soil is reused to reduce the preparation cost.

[0020] S3. Sinter into blocks Pour the mixed yellow mud slurry into the sintering box, and then send the sintering box into the heating furnace. The heating furnace provides a high-temperature environment to evaporate the water in the yellow mud slurry and burn the organic matter. At the same time, the components in the yellow clay and the wastewater undergo chemical reactions at high temperatures to form a hard sintered body.

[0021] Among them, the sintering process uses segmented temperature control: The first stage: Control the heating rate at 5 - 8 °C / min, heat up to 200 - 300 °C, and keep it warm for 30 - 60 min to discharge the bound water; The second stage: Control the heating rate at 8 - 10 °C / min, heat up to 750 - 850 °C, and keep it warm for 1 - 2 h to sinter into shape.

[0022] To avoid too long sintering time, control the thickness of the yellow mud slurry at 4 - 8 cm. And the holding time is adjusted according to the thickness of the yellow mud slurry, and there is a positive correlation between the holding time and the thickness of the yellow mud slurry.

[0023] By heating up slowly, avoid cracks caused by too fast heating rate, so as to prepare sintered blocks with high strength.

[0024] S4. Crush and granulate When the sintered body cools to room temperature, carry out crushing treatment on it. During the crushing process, it is necessary to pay attention to controlling the size and shape of the particles to meet the requirements of subsequent use or treatment.

[0025] S5. Screen and pack Screen the granulated soil obtained after crushing to obtain granulated soil with different particle size gradings. The granulated soil after crushing can be used in fields such as soil improvement and horticulture.

[0026] Example 2 Different from Example 1, the sintering process adopts segmented temperature control: The first stage: The heating rate is controlled at 25 - 35 °C / min, heated to 200 - 300 °C, and kept warm for 30 - 60 min to discharge the bound water; The second stage: The heating rate is controlled at 30 - 40 °C / min, heated to 750 - 850 °C, and kept warm for 1 - 2 h to sinter and form.

[0027] By rapidly heating, cracks are generated during the firing process to reduce the strength of the finished product, so as to facilitate subsequent crushing into granulated soil and reduce the crushing difficulty.

[0028] Granulated soil is prepared by mixing the steel pipe-cooled wastewater with yellow clay. The steel pipe-cooled wastewater not only contains iron and carbon elements beneficial to plant growth, but also contains many other trace mineral elements, which are crucial for promoting the healthy growth of plants. Through this measure, the reuse of wastewater is achieved, which not only greatly reduces the cost of wastewater treatment, but also brings certain economic benefits to the enterprise. More importantly, the prepared granulated soil exhibits many excellent properties: it can effectively store water to ensure soil humidity; it has good drainage performance to avoid waterlogging of plant roots; at the same time, its internal porous structure is conducive to air circulation, providing sufficient oxygen for plant roots; in addition, this granulated soil is also convenient for applying base fertilizer to provide continuous nutritional support for plant growth. Therefore, this granulated soil has broad application prospects in soil improvement and is of positive significance for improving soil quality and promoting plant growth.

[0029] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing granular soil using metal processing cooling wastewater and yellow mud, characterized in that: The following steps are involved: S1. Cooling wastewater from steel pipes to precipitate; S2. Mixing the precipitated wastewater with yellow mud to form yellow mud slurry; S3. Pour the yellow mud slurry into a sintering box and send it into a heating furnace to sinter into blocks; S4. Crush the sintered body to obtain granular soil.

2. The method for preparing granular soil by using metal processing cooling wastewater and yellow mud according to claim 1, characterized in that: Step S1 also includes adjusting the pH of the wastewater to 6-6.

5.

3. The method for preparing granular soil by using metal processing cooling wastewater and yellow mud according to claim 1, characterized in that: Step S3: The yellow mud slurry is laid in the sintering box with a thickness of 4-8 cm.

4. The method for preparing granular soil by using metal processing cooling wastewater and yellow mud according to claim 1, characterized in that: The sintering process of step S3 adopts segmented temperature control: The first stage: heating to 200-300℃, keeping warm for 30-60min, and discharge bound water; The second stage: heating to 750-850℃, keeping warm for 1-2h, and sintering.

5. The method for preparing granular soil by using metal processing cooling wastewater and yellow mud according to claim 4, characterized in that: The heating rate in the first stage is controlled at 5-8°C / min, and the heating rate in the second stage is controlled at 8-10°C / min.

6. The method for preparing granular soil by using metal processing cooling wastewater and yellow mud according to claim 4, characterized in that: The heating rate in the first stage is controlled at 25-35°C / min, and the heating rate in the second stage is controlled at 30-40°C / min.

7. The method for preparing granular soil by using metal processing cooling wastewater and yellow mud according to claim 1, characterized in that: The granular soil obtained in step S4 is screened to obtain granular soil of different particle size classifications.

8. Granulated soil prepared by the method for preparing granulated soil according to any one of claims 1 to 7.