TWI406717B - Water-retention material and method for producing the same - Google Patents

Abstract

The present invention relates to a water-retention material, which comprises spent diatomaceous earth and water treatment plant sludge to achieve the object of recycling spent diatomaceous earth and water treatment plant sludge. The present invention also relates to a method for producing a water-retention material, which comprises the following steps: (a) providing a row material, comprising spent diatomaceous earth; (b) grinding the row material and sieving the same; (c) compression molding the row material processed by the step (b); and (d) sintering the molded material.

Description

Water retaining material and method of manufacturing same

The invention relates to a water-retaining material, in particular to a water-retaining material with excellent water absorption and stability.

The diatomaceous earth is a fossil of algae, which has the characteristics of heat resistance, acid and alkali resistance and light weight. Its structure is porous, making it the best natural filter filler and excellent adsorbent. The diatomaceous earth is widely used as a filler such as a heat-insulating fireproof filler, a filter aid such as a food processing filter, an abrasive such as an essential component of an exfoliating cream, and an insecticide such as a pesticide pest control. In the use of filter media filtered by the food processing industry, it is estimated that 5,000 metric tons of waste diatomaceous earth is produced each year. These waste diatomaceous earths are mostly used as porphyry soils and recycled as porous adsorbents. Buried way to deal with.

The main source of clean water sludge is the waste sludge obtained from the sludge dewatering machine after the collected wastewater is treated by the wastewater treatment program. Due to the increase in population and the popularity of water for people's livelihood, Taiwan produces about 120,000 tons of clean water sludge per year. The characteristics of clean water sludge are simple and the content of heavy metals is low. Common re-use and utilization such as: aggregate, cement, road materials and adding appropriate amount of fertilizer to supplement nutrients for agricultural or horticultural use, etc., but most of the disposal methods are still based on landfill. .

In summary, landfill treatment is not the most efficient way to use resources. Therefore, today, as environmental issues are increasingly valued, there is an urgent need for a more appropriate way to recycle waste algae with increased annual production. With clean water sludge.

Therefore, the main object of the present invention is to provide a water-retaining material which uses waste diatomaceous earth and/or purified water sludge as a main material to achieve the goal of resource recovery.

Still another object of the present invention is to provide a method for producing a water retentive material which uses waste diatomaceous earth and/or purified water sludge as a main material to obtain a water repellent material having excellent water absorption and stability.

In order to achieve the above object, the present invention provides a water retentive material comprising: 50 to 99% by weight of waste diatomaceous earth; and 1 to 50% by weight of purified water sludge.

Preferably, the waste diatomaceous earth and the aforementioned purified water sludge are subjected to sintering treatment.

The present invention further provides a water retentive material comprising: 50 to 100% by weight of waste diatomaceous earth, wherein the waste diatomaceous earth is sintered.

Preferably, the water retentive material further comprises purified water sludge.

Preferably, the sintering temperature is 800 to 1400 °C.

Preferably, the water retentive material has a fineness of 300 to 1400 m ² /Kg.

The invention further provides a method for producing a water retentive material, comprising the steps of: (a) providing a raw material comprising waste earth algae; (b) grinding and sieving the raw material; (c) Step (b) processing the raw material after press molding; and (d) sintering the raw material subjected to the above press molding.

Preferably, the aforementioned step (a) further comprises drying the aforementioned raw materials.

Preferably, the aforementioned step (b) is sieved through a sieve of 60 to 400 mesh.

Preferably, the aforementioned raw material further comprises purified water sludge.

Preferably, before the step (c), the ratio of the diatomaceous earth and the water purification sludge is adjusted.

Preferably, the pressure of the aforementioned step (c) is 20 to 250 kgf/cm ² .

Preferably, the heating rate of the foregoing step (d) is 5 to 20 ° C / min.

Preferably, the sintering temperature of the aforementioned step (d) is 800 to 1400 °C.

Preferably, the water-retaining material has a pore size of more than 0.1 μm.

In summary, the water-retaining material of the present invention uses waste diatomaceous earth and purified water sludge as main materials, and achieves the purpose of waste recycling, wherein waste diatomaceous earth is used as a substrate to provide water retention function. The purified water sludge is used as a structural reinforcing material to provide strength.

The water-retaining material refers to a substance that can absorb a large amount of water, such as bamboo charcoal, super absorbent resin (SAP), and hydroxypropyl methylcellulose (HPMC). Water-retaining materials are widely used. For example, if they are applied to urban roads to fully absorb rainwater and avoid road area water affecting driving safety, the standard specifications require a water absorption rate of at least 40%.

The invention relates to recovering waste diatomaceous earth and purified water sludge as a water retaining material, wherein the waste diatomaceous earth system is used as a base material to provide a water retention function, and the purified water sludge system is used as a structural reinforcing material to provide strength. . The water retentive material of the present invention is mainly made into a water retaining brick for use in roads; preferably, it meets the standard water absorption rate of at least 40%; preferably, it also conforms to the CNS 382 R2002 (brick making standard) specification. Compressive standard of 3 kinds of bricks (first-class brick compressive strength: 150kgf/cm ² ; second-class brick: 100kgf/cm ² ; third-class brick: 70kgf/cm ² ; general brick compressive strength is usually 35~70kgf/ Cm ² ).

The term "waste algae soil" as used in the present invention means diatomaceous earth which has been used at least once, and the diatomaceous earth which is used as a filter material for the food industry is bulky, but is not limited to waste diatomaceous earth which has been used for other purposes. For example, the waste algae soil used in the present invention is a waste adsorbent from a food plant sewage treatment system.

The "clean water sludge" as used in the present invention refers to a solid-liquid mixed precipitate produced during the process of water purification, and the source thereof is not limited. For example, the purified water sludge used in the present invention is from a water purification plant. The resulting purified water sludge.

The present invention also provides a method for producing a water retentive material. For example, the preparation of the water retentive material of the present invention comprises the steps of: first obtaining the required raw materials (waste algae and/or purified water sludge), and The foregoing raw materials are dried and ground, and the aforementioned grinding may be carried out by a conventional grinding method without limitation, and is preferably ball milling. Next, the ground raw material is sieved, and the purpose of sieving is to use raw material particles having substantially similar particle diameters, which will contribute to the strengthening and stability of the water-retaining material structure in the subsequent sintering process, so in principle, It is not necessary to limit the screen to be used, as long as it can screen raw material particles having substantially similar particle diameters, preferably 60-400 mesh screens; preferably, after the aforementioned screening step, the screens are selected. The fineness of the raw material particles is 300 to 1400 m ² /Kg.

Next, adjusting the ratio of the waste diatomaceous earth and the purified water sludge in the raw material, the waste diatomaceous earth is the substrate of the water-retaining material of the invention, and the proportion thereof is 50-100% by weight; the purified water sludge is the water retention of the invention The structural reinforcing material of the material is in a proportion of 0 to 50% by weight; that is, the water retaining material of the present invention may contain only the waste algae soil without any purified water sludge; preferably, the present invention The water retentive material further contains purified water sludge to provide excellent compressive strength.

After selecting an appropriate ratio, the above-mentioned raw materials are press-formed at a pressure of 20 to 250 kgf/cm ² , but those skilled in the art have a suitable pressure to fix the aforementioned raw materials to a desired shape as appropriate. The foregoing shape is not limited, and may be pressurized to any geometric shape depending on the application requirements of the water retentive material of the present invention.

Then, the raw material after the press molding described above is sintered. The foregoing sintering can be carried out in any high temperature sintering manner known in the art including, but not limited to, an electric kiln, a gas kiln or a material kiln. The sintering temperature is 800 to 1400 ° C; the heating rate is 5 to 20 ° C / min. The aforementioned sintering temperature affects the strength and mineral composition of the water retentive material of the present invention. After sintering, the water retentive material of the present invention is completed, which has a porous structure. Preferably, the pores have a pore diameter of more than 0.1 μm; more preferably, more than 1 μm. Further, the mineral composition of the water retentive material of the present invention is mainly composed of cristobalite, which provides good strength and stability.

The following examples are intended to further understand the advantages of the present invention and are not intended to limit the scope of the invention.

Example 1: Analysis of the composition and characteristics of the raw materials of the water retentive material of the present invention

First, the components of the waste diatomaceous earth and purified water sludge of the present invention were analyzed by X-ray Fluorescence Spectrometer (XRF). The results are summarized in Table 1 below:

The results showed that the main component of waste algae soil was cerium oxide (SiO ₂ ), accounting for 94.51%, and the water purification sludge was mainly composed of cerium oxide (SiO ₂ ) and aluminum oxide (Al ₂ O ₃ ). Followed by ferric oxide (Fe ₂ O ₃ ) accounted for 7.21%. The mineral composition of the water retentive material of the present invention was analyzed by X-ray diffraction analyzer (XRD). Please refer to the first figure for the XRD pattern of the waste diatomaceous earth and purified water sludge of the present invention, showing that the main mineral composition of the waste diatomaceous earth is cristobalite (christobalite, peak 1 in the figure), and the water purification The mud is dominated by quartz (quartz, peak 2 in the figure) and contains a small amount of cerium oxide (SiO ₂ , peak 3 in the figure).

Next, according to the NIEA R208.03C standard method announced by the Environmental Protection Institute, the pH value (pH value, mixed with distilled water in a ratio of 1:10) and specific gravity of the waste diatomaceous earth and purified water sludge used in the present invention are tested. Physical properties such as specific weight), density, moisture, and loss of ignition. The results are summarized in Table 2 below:

Finally, according to the standard method of NIEA R208.03C published by the Environmental Protection Institute, the total amount of heavy metals and the heavy metal TCLP (toxicity dissolution procedure) dissolution of the waste diatomaceous earth and purified water sludge used in the present invention were measured by atomic absorption spectrometry (FLAA). Concentration, the results of the series are in the following three:

It can be seen from Table 3 above that the waste algae soil does not contain any heavy metals, and the total amount of heavy metals in the purified water sludge has the highest zinc (Zn) content of 81.67 mg/kg, followed by the chromium (Cr) content of 66.67 mg/ Kg, and TCLP dissolution test results are below the detection limit. In general, the raw materials of the water retentive material of the present invention have no doubts that are harmful to the environment.

Example 2: Preparation of water-retaining material of the invention

Referring to the second drawing, after obtaining the waste diatomaceous earth and the purified water sludge required for the raw materials, the raw materials were dried at a temperature of 105 ° C, and then the raw materials were ground by ball milling for 3 hours to uniformly pulverize the raw materials. The milled raw material was passed through a 100-mesh screen to screen raw material particles having substantially similar particle sizes. Then adjust the distribution of raw materials as shown in the following table four:

The samples A to E prepared in the above ratio were pressure-molded at a pressure of 50 kgf/cm ² and placed in an electric kiln, and each of the above samples was sintered at temperatures of 1000 ° C, 1100 ° C, 1200 ° C, and 1270 ° C, respectively. The rate is 5 ° C / min. The water retentive material of this example is obtained after the sintering is completed.

Example 3: Analysis of the properties of the water retentive material of the present invention [mineral composition]

The mineral composition of the water retentive material of the present invention was first analyzed by an X-ray diffraction analyzer (XRD). Please refer to the third and third B diagrams, respectively, for the XRD pattern of the water-repellent material obtained by sintering the samples A to E at 1000 ° C or 1100 ° C in the foregoing second embodiment. The figure shows that the mineral composition of all samples is dominated by cristobalite (Cristobalite, peak 1 in the figure), but samples B~E sintered at 1000 °C and 1100 °C contain a small amount of quartz (quartz, peak 2 in the figure) ). .

Referring to FIG. 3C and FIG. 3D, respectively, the XRD patterns of the water-repellent materials obtained by sintering the samples A to E at 1200 ° C or 1270 ° C in the foregoing Example 2 are respectively obtained. As can be seen from the figure, the mineral composition of the above samples after sintering at 1200 ° C and 1270 ° C is cristobalite (peak 1 in the figure).

Cristobalite is a stable crystal phase with high strength produced by high temperature treatment of quartz. It can be seen from the XRD pattern that the mineral composition of the water retentive material of the present invention is mainly composed of cristobalite, and the water retentive material of the present invention has high strength and high. The advantage of stability.

[compressive strength, water absorption and dehydration rate]

First, the compressive strength of the water-repellent material of the second embodiment is measured. Please refer to the experimental results in the fourth figure, taking the X-axis as the sample A~E and the Y-axis as the compressive strength (MPa) to show each sample at 1000 °C (◆ The compressive strength of the obtained water-retaining material sintered at 1100 ° C (■), 1200 ° C (▲), and 1270 ° C (□). As can be seen from the data in the figure, the compressive strength increases substantially as the sintering temperature increases, and increases as the content of the purified water sludge increases. This result is consistent with the mineral composition analysis of the above water-retaining material. Since the main mineral composition of the purified water sludge is quartz, a high-strength and stable cristobalite crystal phase is formed after sintering, and the strength and stability of the water-retaining material are improved. .

Referring to Figure 5 again, the water absorption rate of the water-repellent material of the second embodiment is examined. The X-axis is the sample A~E, and the Y-axis is the water absorption rate. The samples are displayed at 1000 ° C (■), 1100 ° C (▲), The water absorption rate of the water-retaining material obtained by sintering at 1200 ° C (Δ) and 1270 ° C (□). The results show that the water-repellent materials of the present invention sintered at 1000 ° C, 1100 ° C, 1200 ° C and 1270 ° C have a water absorption of more than 50%, and the water absorption rate decreases as the sintering temperature increases, also with the purified water sludge. The content is increased and decreased.

Combined with the above test data, it is obvious that the water-retaining material prepared at the sintering temperature of 1270 ° C has excellent performance regardless of compressive strength and water absorption. Please refer to Table 5 below to systematically complete the above samples A~E at 1270 °C. Compressive strength and water absorption of the water-retaining material obtained by sintering:

It can be seen from Table 5 above that all water-retaining materials listed above have a water absorption rate of more than 50%, which meets the water absorption requirement of at least 40% of the water-retaining materials applied to the road surface; in addition, all the water-retaining materials in Table 5 are also excellent. The compressive strength, especially for sample E, is 1 MPa = 10.17918 Kgf/cm ² , that is, the compressive strength of sample E is 189.9735 Kgf/cm ² , which has complied with the three specifications of CNS 382 R2002 (Brick Standard). Brick pressure resistance standard.

Next, please refer to the sixth figure, showing the dehydration rate of the water-repellent materials obtained by sintering samples B (▲), C (■), D (□) and E (△) at 1270 ° C. The focus of the observation is on the dehydration parameters ( The value of ) represents the time required for the moisture contained in the sample to desorb half. It can be seen from the results that the dehydration rates of samples B~E are not far from each other, and are between 2 and 4 hours.

[Porosity and Pore Aperture]

Next, the porosity of the water retentive material of Example 2 was tested. Please refer to the experimental results in the seventh figure. The X-axis is the sample A~E, and the Y-axis is the porosity. The samples are displayed at 1000 °C (■), 1100 ° C (▲), 1200 ° C (△) and 1270 ° C (□ The porosity of the obtained water retaining material is sintered. As can be seen from the data in the figure, in addition to the large variation in porosity at the sintering temperature of 1270 ° C (□), the variation of the basic porosity with the content of the purified water sludge is not significant. In addition, the porosity decreases as the sintering temperature increases. The test results in this part are consistent with the results of the above test water absorption. Comparing the results of the above test compressive strength, it can be seen that although the sintering temperature is increased, the strength of the overall water-retaining material can be improved. However, the porosity of the water retaining material is lowered, thereby reducing the water absorption rate.

Finally, the pore diameter of the water-retaining material obtained in the aforementioned samples A to E was measured by a mercury intrusion porosimeter (Micromeritics AutoPore IV 9500). Please refer to the eighth figure to show the pore size of the water-repellent material obtained by sintering the sample A at 1000 ° C, 1100 ° C, 1200 ° C or 1270 ° C. From the data in the figure, the pore diameter of almost all pores is larger than 0.1 μm. More precisely, most of the apertures are larger than 1 micron.

Referring again to Figures 9A, 9B and 9C, the pore size of the water retentive material obtained by sintering the aforementioned samples B, C, D and E at 1100 ° C, 1200 ° C or 1270 ° C, respectively. The results show that the pore size of most of the sample pores is above 0.1 micron, especially at 1270 ° C. The pore size of the pores is mostly above 1 micron. In general, the pores of the water-retaining material of the present invention belong to macropores (micropore pore size: less than 2 nm; macropore pore diameter: more than 50 nm; pore diameter between 2 and 50 nm is called mesopores) .

It will be apparent to those skilled in the art that various changes can be made in accordance with the embodiments of the present invention without departing from the spirit of the invention. Therefore, it is to be understood that the invention is not limited by the scope of the invention, and is intended to cover the modifications of the spirit and scope of the invention.

The first figure shows the XRD pattern of waste diatomaceous earth and purified water sludge.

The second figure shows the preparation process of the water retentive material of the second embodiment of the present invention.

The third A graph shows the XRD pattern of the water retentive material of the present invention sintered at 1000 °C.

The third B graph shows the XRD pattern of the water retentive material of the present invention sintered at 1100 °C.

The third C-picture shows the XRD pattern of the water-retaining material of the present invention sintered at 1200 °C.

The third D graph shows the XRD pattern of the water retentive material of the present invention sintered at 1270 °C.

The fourth figure shows the compressive strength of the water repellent material of the second embodiment of the present invention.

The fifth figure shows the water absorption rate of the water repellent material of the second embodiment of the present invention.

Fig. 6 is a graph showing the dehydration rate of the water repellent material of Example 2 of the present invention.

The seventh figure shows the porosity of the water retentive material of the second embodiment of the present invention.

The eighth figure shows the pore diameter of the water retentive material of the sample A of the present invention.

Figure 9A shows the pore size of the water retentive material of the inventive samples B, C, D and E sintered at 1100 °C.

The ninth B-ray shows the pore diameter of the water-repellent material of the inventive samples B, C, D and E sintered at 1200 °C.

The ninth C-picture shows the pore diameter of the water-repellent material of the inventive samples B, C, D and E sintered at 1270 °C.

Claims (17)

A water-retaining material comprising: 50 to 99% by weight of waste diatomaceous earth; and 1 to 50% by weight of purified water sludge; wherein the water-retaining material has a compressive strength of 5.97 to 8.63 MPa and a water absorption rate of 51.39 -79.85%. The water-repellent material according to claim 1, wherein the waste diatomaceous earth and the water purification sludge are subjected to sintering treatment. The water-repellent material according to claim 2, wherein the sintering temperature is 1270 to 1400 °C. The water retentive material according to claim 1, wherein the water retentive material has a fineness of 300 to 1400 m ² /Kg. The water-repellent material according to claim 1, wherein the pore diameter of the pores is greater than 0.1 μm. A water-retaining material comprising: 50-100 wt% waste diatomaceous earth, wherein the waste diatomaceous earth is sintered; wherein the sintering temperature is 1270-1400 ° C; wherein the pressure-resisting material has a compressive pressure The strength is 5.97-18.63 MPa and the water absorption rate is 51.39-79.85%. The water-repellent material according to claim 6, wherein the water-retaining material further comprises purified water sludge. The water-repellent material according to claim 6, wherein the water-repellent material has a fineness of 300 to 1400 m ² /Kg. The water retentive material according to claim 6, wherein the pore size of the pores of the water retentive material is greater than 0.1 μm. A method for producing a water-retaining material, comprising the steps of: (a) providing a raw material comprising waste earth; and (b) grinding and sieving the raw material; (c) press-forming the raw material treated by the above step (b); and (d) sintering the raw material subjected to the press molding; the sintering temperature is 1270 to 1400 °C. The method of claim 10, wherein the aforementioned step (a) further comprises drying the aforementioned raw material. The method of claim 10, wherein the step (b) is sifted through a sieve of 60 to 400 mesh. The method of claim 10, wherein the raw material further comprises purified water sludge. The method of claim 13, wherein the step (c) further comprises adjusting the ratio of the diatomaceous earth and the water purification sludge. The method of claim 10, wherein the pressure of the aforementioned step (c) is 20 to 250 kgf/cm ² . The method of claim 10, wherein the heating rate of the aforementioned step (d) is 5 to 20 ° C / min. The method of claim 10, wherein the pore size of the pores of the water-retaining material is greater than 0.1 μm.