CN1247855C - Deinking method for waste paper float selection and equipment thereof - Google Patents

Abstract

The present invention relates to a waste paper floatation deinking method and an apparatus thereof. The method comprises the following steps: (1), sieving, dewatering and concentrating waste paper pulp to 8% to 12%; (2), adding 4 to 8 wt% of sodium silicate and 0.5 to 1.2 wt% of a floatation agent according to the amount of dry waste paper pulp, regulating the pH value of sodium hydroxide to 9 to 12 and defibering; (3), adding the floatation agent and water with the content of the floatation content as 0.5 to 1.0 wt%. The apparatus comprises an oblique sieve, a defibering device, a stirring barrel, a floatation apparatus and a vibration sieve, wherein the floatation apparatus has a flotation column, a pulp inlet main pipe is vertically arranged at the inner upper part of a column-shaped body of the floatation apparatus which is connected with an air inlet pipe, and the lower end port of the pulp inlet main pipe corresponds to the panel of a reflecting cone. Pulp forms a stable pulp suspension column body by the reflection of the panel of the reflecting cone, air simultaneously enters and uniformly mixes with the pulp so as to generate bubbles, and the bubbles suspend by penetrating through the suspension body. The floatation apparatus is adopted to carry out floatation and deinking so that ink and fiber are separated, and good pulp for making paper is obtained. The method of the present invention obviously improves the whiteness and the fiber yield of paper pulp from waste paper.

Description

Deinking method for waste paper float selection

Technical field

The present invention relates to a kind of deinking method for waste paper float selection and equipment thereof.

Background technology

Develop rapidly along with Technological Economy, the progress of society, popularizing of office automation, and the raising of material and cultural life, people are to the demand of paper and paper products, especially medium-to-high grade paper demand is increasing rapidly, and the waste paper amount increases with the growth of consumption figure, and reduces day by day as trees and other plant of the raw material of papermaking.The characteristics of paper industry are power consumption and water consumption height, and papermaking needs a large amount of timber, and producing one ton of paper needs 5 meters ³Timber (about 50 trees), water are gone back consumes energy and chemicals more than 300 tons, papermaking simultaneously produces a large amount of waste water,waste gas and industrial residue and toxic substance in process of production, easily environment is polluted, You Yishui pollutes the most serious, accounts for 30% of gross contamination.Paper is through after writing, printing, and the change of internal does not take place the fiber of the inside, can carry out the second time to the string of the inside and utilize, and it is processed into paper again.It is reported that 1 ton of waste paper can recycled paper more than 800 kilogram, can save 4 cubic metres of timber, be equivalent to cut less 17 big trees, save 1.2 tons of coals, 600 degree electricity, 100 cubic metres of water, 300 kilograms of industrial chemicals, and reduce by 35% water pollution, thereby save a large amount of environmental improvement expenses.

Because world today's environment worsens day by day, people's environmental consciousness also strengthens day by day, for energy savings, reduce pollutional load, reduce deforestation, the benefit that the recycling of waste paper has caused the aspects of bringing after the attention that people are increasing, particularly waste paper utilization such as reducing investment outlay, reduce cost has created huge motive force more for the reuse of waste paper.The waste paper recycling just becomes the developing goal that global paper-making industry is made great efforts implementation.Now, not only there is strict QUALITY STANDARD in American-European developed country to waste paper, and has also formulated corresponding law, rules to recycling, even also gives certain financial subsidies.

Waste paper is good raw material under the existing condition of China's paper industry, because waste paper has more tangible comprehensive benefit compared with using timber papermaking, can provide papermaking inexpensive fibre resources, and its cost is well below log papermaking.The more important thing is that waste paper paper delivery ratio was up to 1.25: 1.For accelerating the development of China's paper industry, also must enlarge waste paper and recycle.

The recycling of waste paper seems even more important to China, because the afforestation rate of China is very low, and the raising of China's paper product quality needs to increase the wood pulp ratio.That brings behind the waste paper utilization simultaneously reduces investment outlay, and the benefit of aspect such as reduce cost produces huge motive force for the reuse of waste paper.Nineteen ninety whole world waste paper utilization amount and utilization rate reach 8,480 ten thousand tons and 35.6% respectively, and nineteen ninety-five then is increased to 1.15 hundred million and 41.4% respectively.Waste paper utilization amount and the utilization rate of estimating 2005 will reach 1.88 hundred million and 48.1%.China's waste paper use rate also reached 37.8% in 1997, but also lagged far behind some developed country's levels of Europe, and for example, the waste paper use rate of France in 1997 is 48.9%, Germany 59%, Holland 71%, Switzerland 65.2%, Britain 71.5%.And the annual waste paper amount that runs off of China has 6,000,000 tons (to be equivalent to 2400 myriametres approximately ³The paper that timber is made), and China's forest owning amount scarcity per capita has only 10% of world average level, far can not provide enough timber to make paper making raw material, and also need from external pulp inlet and paper product every year.Therefore, the potentiality of China's waste paper utilization are still very big.

Therefore no matter from the angle of economy still from the angle of ecological environment, the floatation deinking has very big potentiality, and good market prospects are arranged.

The method of deinking at present mainly contains floatation, washing method and both combinations etc.Floatation accounts for about 80% of world's deinking ability, and this is that fiber loss is few because flotation can high-qualityly remove waste paper printing ink, the yield height, its printing ink particle size range that is suitable for is wide, kind is many, and pollutes little, water consumption uses kinetic energy less with needing, and investment cost is also lower.Flotation technology has deep research and application in mineral processing industry, no matter be floatation equipment development, or regime of agent and technological process aspect, and the experience of many maturations is all arranged, and can use for reference.

Summary of the invention

The purpose of this invention is to provide a kind of pulp brightness that can significantly improve waste paper, and the deinking method for waste paper float selection of fiber yield.

Another object of the present invention provides a kind of facility compact, floor space is little, energy consumption is low, efficient is high, expense the is low used equipment of deinking method for waste paper float selection.

For achieving the above object, the present invention takes following technical scheme: this deinking method for waste paper float selection comprises the steps:

(1) takes from the secondary stock of pulper, be concentrated into 8-12wt% through screening and dewatering;

(2) adding sodium metasilicate and flotation agent in above-mentioned paper pulp, wherein, press the sodium metasilicate of waste paper dry pulp amount adding 4-8wt%, the flotation agent of 0.5-1.2wt%, is 9-12 with the NaOH adjust pH, stirs, discongests; The time of discongesting is 5-30 minute;

(3) add flotation agent and water in the paper pulp after discongesting, the content of flotation agent is 0.5-1.2wt%, carries out floatation and ink removing by floatation equipment, makes printing ink and fiber separation, obtains can be used for the good slurry of papermaking.

In the floatation process of the above-mentioned steps (3) of method of the present invention, the concentration＜1.2wt% of paper pulp.

Flotation agent of the present invention is enuatrol and calcium chloride, and wherein enuatrol is 1: 0.2～1.0 with the ratio of calcium chloride.

The equipment that deinking method for waste paper float selection of the present invention is used, include slanted screen, the outlet of this slanted screen is joined by pipeline and the import of discongesting device, this bottom of discongesting device is provided with outlet, and join by pump, pipeline and the import that mixes the agitator of slurry, the purpose of this agitator is that the paper pulp after discongesting is stirred, so that follow-up flotation.Its underpart is provided with outlet, and by pump, the stock inlet of pipeline and floatation equipment joins, and discharges through good slurry outlet through the good slurry that flotation obtains, and is used for papermaking.

In equipment of the present invention, the floatation equipment of deinking mainly adopts FX type flotation machine (groove type floatation cell), ZCF type ladder diffusion type flotation device (being similar to the jetting type flotation device in the ore dressing), Lamort convection type flotation device and Si Wei mark (swemac) vertical type cylinder flotation device.

In equipment of the present invention, the floatation equipment of deinking can adopt with improved microfine ore dressing uses flotation column as floatation equipment, and this flotation column is the vertical type cylinder floatation equipment, but different this Wei Make (swemac) flotation device.This flotation column includes cylindricality and holds body, upper vertical in this cylindricality is held body is provided with the into slurry person in charge, this advances the slurry person in charge and stretches out cylindricality and hold external, the upper port of advancing the slurry person in charge is stock inlet and taps into tracheae, to hold the vertex of a cone of the reflection cone panel in the body middle part sharp relative with being located at cylindricality to advance lower port that slurry is responsible for, the bottom that holds body in cylindricality is provided with good slurry outlet, and the upper side of holding body in cylindricality is provided with the foam weir plate, and the periphery of this foam weir plate is provided with foam tank.Slurry feeds from the flotation column central vertical by pump, through the reflection of the reflection cone panel at middle part, forms stable slurry suspension cylinder in post.In feed, air enters from the upper port of advancing the slurry person in charge simultaneously, and with the evenly mixed bubble that produces of slurry, bubble passes the suspended substance come-up.In flow process, printing ink contacts and collides with air, and adheres on the bubble, rises to liquid level and forms materialization froth bed, and the foam weir plate place foam that holds the top of body in cylindricality overflows, and good slurry then exports discharge from the good slurry of the bottom of post.Utilize the slurry-inlet valve door to regulate paper pulp flow velocity and air inflow, thereby change the size of bubble.Come the high efficiency printing ink of removing different-grain diameter in view of the above.

In the methods of the invention, be 9-12 with the NaOH adjust pH.When discongesting, the pH value has remarkable influence to deinking, and along with the rising of pH value, whiteness and fiber yield all improve, but alkalescence is too strong, also makes yellowing reversion of pulp, and pH maintains 9-12 when therefore discongesting, and is advisable with pH=10-11 especially.NaOH main effect in discongesting process is saponification, make the connection material saponification in the printing ink and break away from fiber, also make filler, colloidal material saponification in the waste paper, the wetting expansion of fiber and discongest more complete, thereby help deinking, improve whiteness, the saponification of fiber simultaneously increases its hydrophily, has also improved the yield of fiber.

In the methods of the invention, the consumption of the sodium metasilicate in the paper pulp of waste paper is 4-8wt%.Sodium metasilicate plays peptizaiton in deinking process, prevent the ink particle of discongesting out, is attached to the fiber surface of paper again, also make the wetting expansion of fiber, prevent that fibril aggregation is agglomerating, prevent carrying secretly mutually of fiber and printing ink, thereby improve whiteness and fiber yield.Consider deinking efficiency and reagent cost, the sodium metasilicate consumption is advisable with 4-8wt%.

In the methods of the invention, flotation agent will influence fibre whiteness and yield, flotation agent discongest with flotation in play double action, discongest in the process, flotation agent and other medicament be jointly to ink emulsification, disperses and infiltration, impels it to break away from from fiber; In the floatation process, remaining flotation agent has the function of collecting and foaming, reduces the surface tension of printing ink, produces tiny bubble, adheres to the printing ink come-up.Along with collector dosage increases, whiteness improves, it is changeable sticking that bubble becomes, carrying fiber secretly increases, reduce the selectivity of collecting agent, cause yield to descend, take all factors into consideration deinking efficiency and production cost, add the flotation agent of 0.5-1.2wt% when determining to discongest by waste paper dry pulp amount, the content of flotation agent is controlled to be and adds 0.5--1.2wt% during flotation.

Discongesting in the step of the inventive method, the time of discongesting can be 5-30 minute.The time of discongesting is lower than the raising that influenced whiteness in 5 minutes, and the time was longer than 30 minutes, and the whiteness increasing degree is little, so the time of discongesting is 5-30 minute.

In the flotation implementation step of the inventive method, selected two kinds of floatation equipments (groove type floatation cell and flotation column) for use, the time of its flotation is different because of different equipment.For groove type floatation cell, in floatation process, in 2 minutes, have on a large amount of China ink grains outstanding, this stage pulp whiteness increase rate is big, surpasses 4 minutes foam volumes and reduces, and color shoals, the fiber emersion of a spot of band China ink grain is arranged frequently, and this stage whiteness improves little, but the rate of recovery descends.Therefore flotation time was advisable with 2-4 minute.And flotation column dwindles greatly, plants as long as 0.5-2 divides.

In the flotation step of the inventive method, the concentration of the paper pulp of waste paper is＜1.2wt%.The pulp density of waste paper reduces, and can obviously improve flotation effect, and this is matter because paper pulp has specific characteristics, concentration plays decisive influence to the dispersion of paper pulp, when concentration was rarer, the fiber in the paper pulp can well disperse, and created favourable flotation environment, fiber China and Mexico grain carry minimizing secretly, along with the increase of pulp density, the dispersiveness of slurry and flowability be variation all, begins to occur the poly-group of fiber, the poly-group of the fiber that has rises with bubble, causes fiber loss; What have carries ink particle secretly, causes whiteness to descend.But concentration is too rare, and the amplitude that index improves is little, but reduces the dried paper treating capacity of unit greatly.Therefore, floatation concentration is best with 0.5-1.2wt%.

The present invention is exactly according to China's national situation, absorb external advanced experience, start with from the angle of economy, environmental protection and water saving, utilize the intersection of subject, use for reference the sorting mineral technology, the fine particle mineral flotation experience of separating particularly, and technology, equipment and medicament taken all factors into consideration the floatation and ink removing method of research.

Description of drawings

Fig. 1 is the process flow diagram of the inventive method

Fig. 2 is the equipment schematic diagram in the technological process of the present invention

Fig. 3 is the flotation column structure chart of present device

The specific embodiment

As shown in Figure 1, the equipment that deinking method for waste paper float selection of the present invention is used, include slanted screen 1, the outlet of this slanted screen 1 is joined by pipeline and the import of discongesting device 2, and this bottom of discongesting device 2 is provided with outlet, and the import of the agitator 4 by pump 3, pipeline and belt stirrer is joined, the bottom of this agitator 4 is provided with outlet, and by pump 5, the stock inlet of pipeline and flotation column 6 joins, and the good slurry outlet of this flotation column 6 connects vibrating screen 7 by pipeline.

As shown in Figure 1 and Figure 2, the paper pulp (abbreviating magma as) of waste paper is concentrated into 8-12wt% through slanted screen 1 screening and dewatering, magma after concentrating put into discongest device 2, and add sodium metasilicate, flotation agent, wherein, press the sodium metasilicate that waste paper dry pulp amount adds 4-8wt%, the flotation agent of 0.5-1.2wt%, and be 9-12 with the NaOH adjust pH, stir, discongest.Be transported to agitator 4 by pump 3 then, the purpose of agitator is that the paper pulp after discongesting is stirred, so that follow-up flotation.Its underpart is provided with outlet, and join by the stock inlet of pump 5, pipeline and flotation column 6, paper pulp after stirring in agitator 4 is transported in the flotation column 6 by pump 5, and add flotation agent and water, and wherein the concentration of paper pulp is＜1.2wt%, the content that makes flotation agent is 0.5-1.2wt%, carry out floatation and ink removing by flotation column 6, the China ink of deviating from is with discharge of wastewater, and the paper pulp after the deinking is transported in the vibrating screen 7, adds water simultaneously and washs.Isolate the final products that good slurry is the inventive method by vibrating screen 7, the liquid after the washing is sent in the agitator 4 by pump 8 again, recycles.

As shown in Figure 3, in equipment of the present invention, the floatation equipment of deinking adopts improved microfine ore dressing to use flotation column as floatation equipment, and this flotation column is the vertical type cylinder floatation equipment.This flotation column includes cylindricality and holds body, this cylindricality is held body and is made up of cylindrical shell 39 and cone 40, and connect with flange 38, upper vertical in this cylindricality is held body is provided with the into slurry person in charge 36, this advances the slurry person in charge 36 and stretches out cylindricality and hold external, the upper port of advancing the slurry person in charge 36 is stock inlet and taps into tracheae 35, advancing slurry is responsible for 36 lower port to hold the vertex of a cone of the reflection cone panel 37 in the body middle part sharp relative with being located at cylindricality, the bottom that holds body in cylindricality is provided with good slurry outlet, the upper side of holding body in cylindricality is provided with foam weir plate 44, and the periphery of this foam weir plate 44 is provided with foam tank 45.Agitator 4 is by pump 5, pipeline and advance slurry and be responsible for 36 stock inlet and join, and is provided with slurry-inlet valve door 32 on pipeline.On cylindricality appearance body, be provided with adding inlet and covering (figure does not show) of medicament and water.The good slurry outlet of holding the bottom of body in cylindricality connects U-shaped and very starches drainage conduit 41, very starch the lower port that drainage conduit 41 connects threeway 43 again at this U-shaped, the upper port of this threeway 43 communicates with atmosphere, and line is taken in the another port of this threeway 43, good slurry is discharged, connect vibrating screen 7 by pipeline.The height and position of this threeway 43 is the height that cylindricality is held the liquid level of the slurries in the body.During the work of this flotation column, slurries are responsible for 36 and are fed from the flotation column central vertical by advancing slurry, and the reflection through the reflection cone panel 37 at middle part forms the suspension cylinder in post.In feed, air enters from the upper port of advancing the slurry person in charge 36 simultaneously, and with the evenly mixed bubble that produces of slurry, bubble passes the suspended substance come-up.In flow process, printing ink contacts and collides with air, and adheres on the bubble, rises to liquid level and forms materialization froth bed, and the foam weir plate 44 place's foams that hold the top of body in cylindricality overflow, and good slurry then exports discharge from the good slurry of the bottom of post.Utilize slurry-inlet valve door 32 to regulate paper pulp flow velocity and air inflow, thereby change the size of bubble.Come the high efficiency printing ink of removing different-grain diameter in view of the above.

Adopt method of the present invention, behind floatation and ink removing, the old paper stock whiteness can improve the 15-20 degree, and the fiber yield reaches 85-90wt%, can be applicable, and makes this technology industrialization.

Method of the present invention adopts conventional floating agent, low toxic and side effect, and printing ink is with moisture low foam output, be difficult for polluting, and can accomplish that the waste water major part recycles, especially flotation operation, water saving, free from environmental pollution, the waste water of partial discharge also reaches discharging standards; Used floatation equipment easily makes, easy to operate, the flotation efficiency height, the pulp treatment amount is big, floor space is little.Method reduced investment of the present invention, cost are low, have improved whiteness, increase the added value of waste paper, and therefore good economic benefits is arranged.

Method of the present invention makes waste paper regenerated utilization not only make full use of the secondary stock resource, saves material and the energy, reduces and pollutes, protect forest resources and ecological environment, and be a useful measure, meet the requirement of China's strategy of sustainable development; And the quality of raising regeneration paper product, increase economic benefit, reduce the import of paper, greatly help development and national economy.

Below with embodiment the inventive method is further described, will help the present invention and advantage thereof are done further to understand, protection scope of the present invention is not subjected to the restriction of these embodiment, scope of the present invention is decided by claim.

Embodiment 1

Magma is the assorted paper of the old archives of complicated component, smashs to pieces through hydraulic pulping paper and disc mill, makes its beating degree reach 30--35 ° of SR, and pulp brightness is 38%, and concentration is 2.5%.With 80 purpose sieves secondary stock is concentrated into 8～12wt%, adds NaOH and make pH=9-12, press waste paper dry pulp amount and add sodium metasilicate: 4～8wt%, flotation agent: 0.5～1.5wt%, discongested 5～30 fens; Again the paper pulp of discongesting is diluted to 0.8～1.2wt% with water, the content of flotation agent is 0.5-1.2wt%, deinking in groove type floatation cell, and flotation time is 2～4 minutes, contains black foam and removes, and product is good slurry in the groove, and the results are shown in Table 1.

Embodiment 2

Its method of operating and equipment are substantially with embodiment 1, and only different is that used raw material is office's waste paper, and the result who obtains also lists in the table 1.

Embodiment 3

Its raw material and method of operating are substantially with embodiment 1, only different is, and used equipment is after the repacking mining flotation column is a flotation column of the present invention, because the fine foam that flotation column produces is many, the foam bed thickness improves flotation effect, and dosing can reduce, it mainly is its facility compact, floor space is little, without agitating device, cuts down the consumption of energy greatly.Flotation column efficient height, a flotation column can replace a plurality of groove type floatation cells, does not need multistage flotation, fiber yield height, the also comparable groove type floatation cell height of floatation concentration reduces the flotation expense.With traditional flotation device relatively, it is low to have a power consumption, takes up an area of for a short time, can seal production, environmental sanitation is good, gas handling system is not stopped up, cylindrical shape does not have the slurry of stagnating and distinguishes.The index of flotation column deinking also is better than groove type floatation cell (seeing Table 1)

Embodiment 4

Its method of operating and equipment are substantially with embodiment 3, and only different is that used raw material is office's waste paper, and the result who obtains also lists in the table 1.

Table 1 embodiment result

	Former pulp brightness, %	Good pulp brightness, %	Good pulp yield, %
				Embodiment 1	38.4	56.8	85.97
Embodiment 2	62	83.5	86.50
				Embodiment 3	38.4	57.1	90.12
Embodiment 4	60	82.5	87.91

In sum, deinking method for waste paper float selection of the present invention can significantly improve pulp brightness, and the fiber yield of waste paper.

Claims (2)

1, a kind of deinking method for waste paper float selection is characterized in that: this method comprises the steps:

(1) takes from the secondary stock of pulper, be concentrated into 8-12wt% through screening and dewatering;

(2) adding sodium metasilicate and flotation agent in above-mentioned paper pulp, wherein, press the sodium metasilicate of waste paper dry pulp amount adding 4-8wt%, the flotation agent of 0.5-1.2wt%, is 9-12 with the NaOH adjust pH, stirs, discongests; The time of discongesting is 5-30 minute;

(3) add flotation agent and water in the paper pulp after discongesting, the content of flotation agent is 0.5-1.2wt%, carries out floatation and ink removing by floatation equipment, makes printing ink and fiber separation, obtains can be used for the good slurry of papermaking.

2, deinking method for waste paper float selection according to claim 1 is characterized in that: in the floatation process of above-mentioned steps (3), and the concentration＜1.2wt% of paper pulp.

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