CN105418145A - Method of preparing porous phosphor absorbing ceramic particle from sludge in water supply plant - Google Patents

Abstract

The invention relates to a method for preparing porous phosphorus-absorbing ceramsite from waterworks sludge. The ceramsite preparation method mainly includes four stages of raw material pretreatment, ball formation, firing and cooling. In the present invention, raw material balls with a particle size of 6-8mm are dried at 105°C for 2 hours to remove moisture, preheated at 300-400°C for 20-30 minutes, roasted at 1150°C for 8-10 minutes, and the finished product of ceramsite is obtained after cooling. . According to the invention, the ceramsite with large specific surface area and strong phosphorus adsorption performance is prepared by controlling the material ratio, the speed of the ball forming machine, the spraying method of the binder, the roasting time and temperature, etc., which can be used as the filler of the sewage treatment system and realizes Resource utilization of sludge from water supply plants.

Description

A method for preparing porous phosphorus-absorbing ceramsite from water supply plant sludge

1. Technical field

The invention relates to a porous phosphorus-absorbing ceramsite, which belongs to the technical field of sludge ceramsite.

2. Technical background

At present, my country's water supply plants mainly purify water sources through a series of processes such as coagulation, sedimentation, filtration and disinfection, remove suspended matter, colloidal substances and other impurities in raw water, and supply purified water to users in the form of pipe network distribution. In the process of drinking water production, a large amount of sludge will be generated, mainly from the sludge discharge water of the sedimentation tank and the flushing wastewater of the backwashing device. In 2014, the annual output of dewatered sludge (with a moisture content of 70%) in urban water plants across the country was close to 22 million tons. The amount of sludge produced will also increase day by day, so the rational disposal of sludge from water supply plants has become an urgent problem to be solved.

Waterworks sludge is a potentially recyclable resource with great commercial value. At present, the disposal of sludge from water supply plants mainly focuses on the direct discharge of sludge water, ocean disposal of dehydrated cakes, land disposal, sanitary landfill, regeneration of aluminum salts and iron salts, land utilization and building material utilization, etc. There are problems such as causing secondary pollution and high follow-up treatment costs. _The main components _of the water supply plant sludge are a large amount _{of silt} , impurities brought in from the source water and the _coagulant added by the water plant. The composition range of ceramsite raw materials is required. Therefore, the sludge from the water supply plant is used as the main raw material, and a certain amount of auxiliary materials and additives are added to make light-weight ceramsite with a certain strength after swelling, which can consume a large amount of dewatered sludge. The problem of final disposal of sludge can also solve the problem of shortage of ceramsite raw materials, especially in line with the principles of harmlessness, reduction and recycling of solid waste in China, and it is a new path of sustainable development.

The core theory of phosphorus removal in water supply plant sludge is used for sewage treatment is that the sludge contains amorphous aluminum ions, which can adsorb phosphorus in sewage and solidify soluble phosphorus. Conventional drinking water treatment technology generally adopts coagulation process, and new coagulants such as polyaluminum chloride have gradually replaced aluminum sulfate and ferric chloride, so that a large amount of aluminum ions are finally deposited in the sludge of water supply plants, which has a strong effect on phosphorus. Adsorption capacity.

In the current patents or studies, there are few studies on the preparation of phosphorus-absorbing ceramsite by using sludge from water supply plants. In the application number 201010130425.6, "A method of firing light-weight ceramsite with sludge from waterworks as the main material" is disclosed. ", the patent uses the prepared ceramsite in the building materials industry; in the application number 201410334856.2, it discloses "a production method of ceramsite and the application of ceramsite and ceramsite". In this patent, the amount of sludge added to the water plant Less, only 10 to 30%. The ceramsite prepared in these patent applications has problems such as less addition of feedwater sludge and low specific surface area. The present invention prepares ceramsite with the industrial by-product of water supply plant sludge, and optimizes the production process of water supply plant sludge ceramsite in view of the existing problems at present, studies the performance and phosphorus adsorption characteristics of water supply plant sludge ceramsite, and discusses The feasibility of using water plant sludge ceramsite to remove phosphorus in the sewage treatment system has been realized, and the resource utilization of water plant sludge has been realized.

3. Contents of the invention

The object of the present invention is to provide a method for preparing porous phosphorus-absorbing ceramsite by using sludge from a water supply plant. The porous phosphorus-absorbing ceramsite has strong phosphorus adsorption performance.

In order to achieve the above object, the preparation steps of the technical solution adopted in the present invention are:

(1) Naturally air-dry the sludge from the water supply plant, put it into a pulverizer and grind it, and sieve it with a 100-120-mesh standard sieve;

(2) Uniformly mix the sludge from the water supply plant with clay to obtain pelletized material, add it to the pelletizing machine to prepare raw meal balls, and spray sodium silicate solution as a binder during the pelletizing process;

(3) After forming into balls, screen out raw meal balls with a particle size of 6-8 mm, put them in an oven and dry them at 105°C for 2 hours to remove moisture, then move them into a muffle furnace and preheat them at 300-400°C for 20-30 minutes , continue to heat up to 1150 ° C for 8 to 10 minutes;

(4) Turn off the heating power of the muffle furnace, open the furnace door after the temperature drops to 400°C, and cool naturally to room temperature to obtain the finished ceramsite.

In the present invention, in the step (2), the sludge from the water supply plant and the clay are uniformly mixed at a mass ratio of (3-4):1.

In the present invention, in the step (3), the speed of the ball forming machine is controlled at 30-40 r/min.

In the present invention, in the described step (3), the balling process alternately adds (sprays) the balling material and the sodium silicate solution, the mass fraction of the sodium silicate solution is 0.5% to 2.0%, and the sodium silicate solution consumption is Material quality 10% to 15%.

The beneficial effect that the present invention has:

The surface of the ceramsite prepared by the present invention is rough, uniformly covered with granular protrusions with a diameter of 1 to 2 mm, and has a rich microporous structure with large micropore gaps (1 to 5 μm), and has strong physical adsorption capacity; The ceramsite prepared by the invention has the characteristics of high mechanical strength, high porosity, and large specific surface area, which are suitable for use as fillers in sewage treatment systems; the present invention uses sludge from water supply plants as a cheap, efficient and new sewage treatment system Phosphorus removal materials have great application prospects in controlling water eutrophication. The present invention uses the water supply plant sludge to produce ceramsite for the sewage treatment system, realizes the harmless, resourceful and industrialized treatment of the water supply plant sludge, is beneficial to the protection of land resources and water resources, and reduces construction investment and operating costs. It has high use value in economic, social and environmental aspects.

4. Description of drawings

Fig. 1 is the apparent structure figure of sludge ceramsite of the present invention;

Fig. 2 is the 3000 times electron microscope microscopic surface structure figure of sludge ceramsite of the present invention;

Fig. 3 is a graph showing the isothermal adsorption of phosphorus by the porous phosphorus-absorbing ceramsite of the present invention.

5. Specific implementation

The present invention will be further described below in conjunction with embodiment.

Example 1

A method for preparing porous phosphorus-absorbing ceramsite with water supply plant sludge, the specific method is as follows:

The production process of sludge ceramsite in water supply plant mainly includes four stages of raw material pretreatment, pelleting, firing and cooling.

(1) Pretreatment

Naturally air-dry the sludge from the water supply plant, put it into a pulverizer, grind it, and sieve it with a 100-mesh standard sieve (with a sieve size of 0.15mm).

(2) into a ball

Mix the sludge and clay from the water supply plant evenly at a mass ratio of 3:1, add them to the ball forming machine to prepare raw meal balls, and spray a solution with a mass fraction of 0.5% sodium silicate as a binder during the ball forming process, sodium silicate The amount of solution used is 10% of the mass of the ball forming material, and the speed of the ball forming machine is controlled to be 40r/min.

(3) dry

After forming into balls, screen the raw material balls with a particle size of 6-8mm, put them in an oven and dry them at 105°C for 2 hours to remove moisture, then move them into a muffle furnace and preheat them at 300°C for 20 minutes, then continue to heat up to 1150°C for roasting 8min.

(4) cooling

Turn off the heating power of the muffle furnace, open the furnace door after the temperature drops to 400°C, and cool naturally to room temperature to obtain the finished ceramsite.

The appearance of the finished product of ceramsite is a spherical solid with grayish-brown rough surface and granular protrusions, the unevenness coefficient K ₈₀ is 1.8, the apparent density is 1.35-1.40g/cm ³ , the cylinder compressive strength is 4.2-4.5Mpa, and the specific surface area is 4.7 ～4.9m ² /g, 1h water absorption 8%～13%, porosity 43%～47%, broken rate ≤1.0%, hydrochloric acid capacity ≤0.8%, loss on ignition ≤0.03%.

Example 2

A method for preparing porous phosphorus-absorbing ceramsite with water supply plant sludge, the specific method is as follows:

The production process of sludge ceramsite in water supply plant mainly includes four stages of raw material pretreatment, pelleting, firing and cooling.

(1) Pretreatment

Naturally air-dry the sludge from the water supply plant, put it into a pulverizer, grind it, and sieve it with a 120-mesh standard sieve (with a sieve size of 0.125 mm).

(2) into a ball

Mix the sludge and clay from the water supply plant evenly at a mass ratio of 4:1, add them to the ball forming machine to prepare raw meal balls, and spray a solution with a mass fraction of 2.0% sodium silicate as a binder during the ball forming process, sodium silicate The amount of the solution is 15% of the mass of the ball forming material, and the speed of the ball forming machine is controlled to be 30r/min.

(3) dry

After forming into balls, screen the raw material balls with a particle size of 6-8mm, put them in an oven and dry them at 105°C for 2 hours to remove moisture, move them into a muffle furnace, preheat at 400°C for 30 minutes, and continue to heat up to 1150°C for roasting 10min.

(4) cooling

Turn off the heating power of the muffle furnace, open the furnace door after the temperature drops to 400°C, and cool naturally to room temperature to obtain the finished ceramsite.

The apparent structure of the finished ceramsite is shown in Figure 1. It can be seen from the figure that the surface of the sludge ceramsite is rough and smooth, and the surface of the ceramsite is evenly covered with granular protrusions with a diameter of 1 to 2 mm, which greatly improves the The surface area of porous phosphorus-absorbing ceramsite brings abundant microporous structure.

The microporous structure of the finished ceramsite is shown in Figure 2. It can be seen from the figure that the surface of the ceramsite is full of large and small pores, there are many ravines, and there is a rich microporous structure, and the micropore diameter ranges from 1 to 5 μm, with strong physical adsorption capacity.

The porous phosphorus-absorbing ceramsite of the present invention has stronger phosphorus adsorption properties, and the isothermal adsorption characteristics conform to the Langmuir equation. The specific research and test methods are as follows:

Main reagents: 5% potassium persulfate solution, 10% ascorbic acid, molybdate solution, phosphate stock solution and standard solution, phenolphthalein, sodium hydroxide solution (1mol/L), sulfuric acid solution (1mol/L)

Main experimental instruments: UV-2450 ultraviolet spectrophotometer; MLS-3750 high-pressure steam sterilizer; constant temperature oscillator (HZQ-R); suction filter (GM-0.33II); FA1004 electronic analytical balance; dryer; pipetting gun.

Dry the pure potassium dihydrogen phosphate (KH ₂ PO4 ) at 110°C for 2 hours, and let it cool in a desiccator. Weigh 0.2197g, dissolve it in water, and transfer it into a 1000ml volumetric flask. Add (1+1) sulfuric acid 5ml, dilute to the mark with water, this solution contains 50.0μg phosphorus (calculated as P) per ml, as KH ₂ PO ₄ stock solution.

(1) Weigh 20g of raw material, place it in 500ml KH ₂ PO ₄ solution, shake at 145r/min at room temperature 25°C, and take samples at 1, 2, 4, 6, 8, 12, 24, 36, 48, and 72 hours , centrifuged at 4000r/min, and the supernatant was taken for colorimetric measurement, and the maximum adsorption capacity of the prepared ceramsite for phosphorus was calculated to be 319mg/kg.

(2) Weigh 10g of the raw material and place it in a 250ml Erlenmeyer flask, add 100mL of KH ₂ PO ₄ solutions of different concentrations (0, 5.0, 10, 20, 30, 40, 50mg/L) respectively, and place it in a constant temperature shaker After oscillating at 145r/min, (25±1)°C for 72h, filter with a 0.45μm filter membrane, measure the phosphorus concentration of the filtrate by colorimetry at 700nm by molybdenum antimony anti-ultraviolet spectrophotometry, according to the concentration change, the research institute prepared ceramsite for Phosphorus adsorption properties.

The isothermal adsorption curve of the prepared ceramsite for phosphorus is shown in Figure 3. The isotherm adsorption process can be divided into two stages: the initial stage, with the increase of solution concentration, the adsorption amount of ceramsite for phosphorus increases rapidly, and the adsorption isotherm It is relatively steep; when the concentration of the solution increases to a certain level, the adsorption gradually weakens, further increasing the concentration of the solution, the amount of phosphorus adsorption increases slowly, and the adsorption tends to balance.

Claims (4)

1. prepare with waterworks sludge the method that multi-hole type inhales phosphorus haydite, comprise raw-material pre-treatment, balling-up, fire and cool four-stage, it is characterized in that the preparation method of described haydite is:

(1) by waterworks sludge natural air drying, put into pulverizer and grind, sieve with 100 ~ 120 object standard sieves;

(2) waterworks sludge and clay Homogeneous phase mixing are obtained balling-up material, join in nodulizer and prepare raw material ball, spray sodium silicate solution in globulation as tackiness agent;

(3) filter out the raw material ball that particle diameter is 6 ~ 8mm after balling-up, put into baking oven dry 2h under 105 DEG C of conditions and slough moisture, move into retort furnace preheating 20 ~ 30min under 300 ~ 400 DEG C of conditions, continue to be warming up to 1150 DEG C of roasting 8 ~ 10min;

(4) close retort furnace heating power supply, after temperature drops to 400 DEG C, open fire door, naturally cool to room temperature, namely obtain haydite finished product.

2. a kind of waterworks sludge according to claim 1 prepares the method that multi-hole type inhales phosphorus haydite, it is characterized in that balling-up material by waterworks sludge and clay by (3 ~ 4): the quality of 1 forms than Homogeneous phase mixing.

3. a kind of waterworks sludge according to claim 1 prepares the method that multi-hole type inhales phosphorus haydite, it is characterized in that controlling nodulizer rotating speed in globulation at 30 ~ 40r/min.

4. a kind of waterworks sludge according to claim 1 prepares the method that multi-hole type inhales phosphorus haydite, it is characterized in that globulation alternately adds (sprinkling) balling-up material and sodium silicate solution, the massfraction of sodium silicate solution is 0.5 ~ 2.0%, and sodium silicate solution consumption is balling-up quality of material 10% ~ 15%.