Method for modifying solid waste after incineration of papermaking sludge to be used as papermaking filler
Technical Field
The invention relates to the field of pulping and papermaking, in particular to a method for modifying solid waste after incineration of papermaking sludge to be used as a papermaking filler.
Background
The paper making industry is an important industry in China, the discharge amount of paper making sludge in China is the first in the world, the discharge amount is about more than 2000 ten thousand tons every year, and most paper mills mainly treat the paper making sludge in modes of landfill, fluidized bed high-temperature incineration and the like. The land is filled in a large amount, which causes waste of land resources. Moreover, as the national environmental requirements have been increased over the years, large-scale paper mills generally require fluidized bed treatment, and the amount of incineration sludge produced thereby has been increasing year by year. Therefore, the reasonable recycling of the papermaking byproducts not only is an environmental protection problem urgently needed to be solved by the current society, but also meets the requirement of China on the construction of 'waste-free cities'.
Sludge ash generated after the incineration of the papermaking sludge has similar physical and chemical properties with some papermaking fillers. In addition, the sludge ash is rough and porous in surface, and is beneficial to the retention of fillers among papermaking fibers.
In 2017, the total yield of paper and paperboard in China is 12542 million tons, about 4000 million tons of inorganic mineral fillers are required on average to meet the production requirement, even if 30 percent of inorganic mineral fillers are replaced, about 1200 million tons of sludge ash composite paper making fillers can be consumed in the paper making industry every year in China, the cost of each ton of composite fillers can be saved by 600 yuan, and the total cost is 72 million yuan per year.
Therefore, the method for carbonizing and modifying the papermaking sludge ash realizes that the papermaking sludge ash is used as a papermaking filler, has great significance for continuously promoting modification of solid waste, reducing landfill amount to the maximum extent, realizing high-value utilization of industrial solid waste of the papermaking sludge ash, reducing papermaking cost and the like, and has good environmental benefit, social benefit and economic benefit.
Disclosure of Invention
The invention aims to provide a preparation method for modifying solid waste after incineration of papermaking sludge to be used as papermaking filler, thereby solving the problems of serious waste of land resources and environmental pollution caused by the accumulation of a large amount of papermaking sludge ash, and simultaneously providing a feasible technical process for the resource high-value utilization of the papermaking sludge.
In order to achieve the above object, the present invention provides the following technical solutions:
a method for modifying solid waste after incineration of papermaking sludge to be used as papermaking filler comprises the following steps:
(1) burning the papermaking sludge to obtain papermaking sludge ash;
(2) mixing the papermaking sludge ash obtained in the step (1) with calcium hydroxide solids, then adding water, fully stirring and mixing, and finally introducing mixed gas of carbon dioxide and air to perform carbonization modification reaction to obtain the composite papermaking filler.
In the method, the papermaking sludge comprises deinking sludge, sludge produced in the pulping and papermaking process, sludge produced in the pulping and papermaking wastewater treatment and sludge produced in the domestic wastewater treatment.
In the method, the incineration temperature is 600-.
In the method, the calcium hydroxide accounts for 1.0-20.0% of the total mass of the papermaking sludge ash, the calcium hydroxide and the water.
In the method, the flow rate of the carbon dioxide is 0.10-1.00L/min.
In the method, the ratio of the carbon dioxide to the air flow rate is 1: 1-4.
In the method, the stirring speed of the carbonization modification reaction is 400-1200 r/min.
In the method, the calcium hydroxide is purchased or prepared from calcium oxide and water.
In the method, the mass ratio of the papermaking sludge to the calcium hydroxide is 1: 1 to 5.
The invention provides a preparation method for modifying solid waste after incineration of papermaking sludge to be used as papermaking filler, which comprises the following steps: burning the papermaking sludge to obtain papermaking sludge ash: and stirring and mixing the papermaking sludge ash and calcium hydroxide, and introducing mixed gas of carbon dioxide and air for carbonization modification to obtain the composite papermaking filler. The invention removes organic substances such as fiber in sludge by means of incineration.
The papermaking sludge provided by the invention comprises deinking sludge, sludge produced in the pulping and papermaking process, sludge produced in the pulping and papermaking wastewater treatment, sludge produced in the domestic wastewater treatment and the like. After being incinerated, the sludge has a physical structure and chemical components similar to the properties of some common papermaking fillers. In addition, the surface of the paper sludge is rough and porous due to the removal of some organic substances, and the paper sludge is easy to remain among fibers.
Compared with the prior art, the invention has the advantages that:
according to the invention, the papermaking sludge ash and the calcium hydroxide are stirred and mixed, and the mixed gas of the carbon dioxide and the air is introduced for carbonization modification, so that on one hand, the whitening of the papermaking sludge ash is realized by crystallizing the calcium carbonate on the surface of the sludge ash, and on the other hand, the carbon dioxide can be directly sourced from flue gas as a raw material, so that the reaction process is simple, and the industrial scale and equipment requirements are not high. Meanwhile, precipitated calcium carbonate is also one of several fillers commonly used in papermaking. The composite filler prepared by the invention is applied to papermaking, not only provides a technical route for high-value resource utilization for papermaking sludge ash, but also creates great economic benefit, environmental benefit and social benefit for papermaking enterprises.
Detailed Description
The invention provides a preparation method for modifying solid waste after incineration of papermaking sludge to be used as papermaking filler, which comprises the following steps:
burning the papermaking sludge to obtain papermaking sludge ash;
and stirring and mixing the papermaking sludge ash and calcium hydroxide, and introducing mixed gas of carbon dioxide and air for carbonization modification to obtain the composite papermaking filler.
The invention obtains the papermaking sludge ash after burning the papermaking sludge. In the present invention, the incineration temperature is preferably 800-1200 ℃, more effectively 900-1000 ℃, and the incineration time is preferably 1.5-6.5h, more preferably 2.0-3.0 h.
After the papermaking sludge ash is obtained, the papermaking sludge ash and calcium hydroxide are stirred and mixed, and carbon dioxide is introduced for carbonization modification, so that the composite papermaking filler is obtained. In the present invention, the mass concentration of the calcium hydroxide is preferably 1.0% to 20.0%, more preferably 7.0% to 15.0%. In the present invention, the flow rate of the carbon dioxide is preferably 0.10 to 1.00L/min, more preferably 0.20 to 0.80L/min. In the present invention, the ratio of the carbon dioxide to the air flow rate is 1: 1-4, more preferably 1: 2-3. In the invention, the stirring speed of the carbonization reaction is preferably 400-1200r/min, and more preferably 600-800 r/min. In the invention, the calcium hydroxide is purchased or prepared by calcium oxide and water. In the present invention, the mass ratio of the paper sludge to the calcium hydroxide is preferably in the range of 1: 1-5, more preferably 1: 1-3.
The following will describe in detail the preparation method of the present invention for modifying solid waste after incineration of paper sludge for use as filler in paper making with reference to the following examples, but they should not be construed as limiting the scope of the present invention.
Example 1
Burning 20g of paper-making deinking sludge at 1000 ℃ for 2.5h to obtain paper-making sludge ash; cooling, and mixing the papermaking sludge ash and calcium hydroxide according to the weight ratio of 1: 1, stirring and mixing uniformly, then continuously adding water, stirring the powder simultaneously, fully stirring and mixing, wherein the reactant calcium hydroxide accounts for 7 percent of the total mass of the papermaking sludge ash, the calcium hydroxide and the water, the stirring speed is 600r/min, then mixing 0.20L/min carbon dioxide and 0.80L/min air, introducing the mixture into a carbonization reaction device, and stopping the reaction after prolonging for 20min when the pH is reduced to 7. The whiteness of the sludge ash is improved from 70.12 percent ISO to 79.12 percent ISO through detection, and the particle size is in the particle size range of common papermaking fillers.
Example 2
Burning 20g of paper-making deinking sludge at 1000 ℃ for 2.5h to obtain paper-making sludge ash; cooling, and mixing the papermaking sludge ash and calcium hydroxide according to the mass concentration of 1: 3, stirring and mixing uniformly, then continuously adding water, stirring the powder simultaneously, fully stirring and mixing, wherein the mass of a reactant calcium hydroxide accounts for 7% of the total mass of the papermaking sludge ash, the calcium hydroxide and the water, the stirring speed is 600r/min, then mixing 0.20L/min carbon dioxide and 0.80L/min air, introducing the mixture into a carbonization reaction device, and stopping the reaction after prolonging for 20min when the pH is reduced to 7. The detected whiteness of the sludge ash is improved from 70.28 percent ISO to 80.99 percent ISO, and the particle size is in the particle size range of common papermaking fillers.
Example 3
Burning 20g of paper-making deinking sludge at 1000 ℃ for 2.5h to obtain paper-making sludge ash; cooling, and mixing the papermaking sludge ash and calcium hydroxide according to the weight ratio of 1: 3, stirring and mixing uniformly, then continuously adding water, stirring the powder simultaneously, fully stirring and mixing, wherein the mass of a reactant calcium hydroxide accounts for 15 percent of the total mass of the papermaking sludge ash, the calcium hydroxide and the water, the stirring speed is 600r/min, then mixing 0.20L/min carbon dioxide and 0.80L/min air, introducing the mixture into a carbonization reaction device, and stopping the reaction after prolonging for 20min when the pH is reduced to 7. The whiteness of the sludge ash is improved from 70.18% ISO to 81.93% ISO through detection, and the particle size is in the particle size range of common papermaking fillers.
From the above embodiment, the invention provides a preparation method for modifying solid waste after incineration of papermaking sludge to be used as papermaking filler, which comprises the following steps: burning the papermaking sludge to obtain papermaking sludge ash; and stirring and mixing the papermaking sludge ash and calcium hydroxide, and introducing carbon dioxide for carbonization modification to obtain the composite papermaking filler. The data show that the method can realize that the incinerated papermaking sludge ash can be successfully used as the papermaking filler, the whiteness of the composite papermaking filler is improved along with the increase of the proportion of the calcium hydroxide, but the whiteness is lower, mainly because the generated calcium carbonate has more nucleation crystals on the surface of the sludge ash when the reactant amount is larger. Meanwhile, when the mass concentration of the calcium hydroxide is increased, the whiteness of the calcium hydroxide is also improved, because when the concentration of the reactant is higher, the collision probability of reactant molecules can be improved, the generated calcium carbonate is favorably crystallized on the surface of the sludge ash, and the whiteness of the composite papermaking filler is improved. The particle size of the composite sludge ash filler generated at the same time is also in the range of the particle size of common papermaking fillers.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.