CN100361920C

CN100361920C - Modified coal ash for concrete mixing material and its production process

Info

Publication number: CN100361920C
Application number: CNB2006100202386A
Authority: CN
Inventors: 余心正
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-01-26
Filing date: 2006-01-26
Publication date: 2008-01-16
Anticipated expiration: 2026-01-26
Also published as: CN1807330A

Abstract

The present invention relates to modified fly ash used as concrete admixtures and a production technology thereof, which is formed by mixing fly ash and liquid slag used for reducing ignition loss; the admixing proportion of the liquid slag is not more than 40%; the fineness of the mixture reaches less than 25% of the weight screen residue amount of a screen of 45 micrometers; the ignition loss of the mixture is not more than 8%. The production technology is carried out by the steps that the fly ash is separated by the air or crushed for cause the fineness to conform to requirements; the liquid slag is magnetically separated and dried until the water content is less than 1%, and the liquid slag is crushed until the fineness conforms to requirements; the fly ash and the liquid slag are homogeneously mixed for forming a finished product according to proportions, wherein the admixing amount of the liquid slag depends on the ignition loss requirements of the mixture. After the fly ash with higher ignition loss is treated, the present invention causes the fly ash to reach the requirements of the concrete admixtures, increases the use value of the part of the fly ash, and solves the problem of the greater quality fluctuation of the fly ash. Simultaneously, the new use of the liquid slag is found for increasing added value.

Description

A kind of modified coal ash as concrete mixing material

One, technical field

The present invention relates to concrete mixing material and production method thereof, also can be described as the utilization that relates to industrial residue, particularly as flyash product of concrete mixing material and preparation method thereof.

Two, background technology

Flyash is the discharge that certainly leads in the coal fire power plant production process, and China is one of country of plant residue quantity discharged maximum in the world.The flyash of collecting in power plant's flue (former ash), general only the need simply processed (levigate or selection by winnowing), makes it to reach certain fineness, just become a kind of concrete mixing material of excellent property.

Since the early 1990s in last century, along with the development of China's city Commercial Concrete, the application of flyash in concrete obtained very great development.But the process for processing of flyash relatively lags behind, and still is in the level that simple (by selection by winnowing and levigate) changes its fineness, is difficult to adapt to the needs of flyash utilisation technology development.

Before this, country is mainly with GB1596-2005 (flyash that is used for cement and concrete), the quality that GB/T18736-2002 (high-strength and high performance concrete mineral additive) comes standard flyash product.In the quality of fly ash index, be that fineness and loss on ignition are two influences the most important index of concrete performance the negativity index except that SO3 content is not more than 3%.Fineness can be satisfied by processing, but the too high problem of loss on ignition is suffered from the solution of having no idea in reality is produced.

Loss on ignition is as good as fineness to the influence of quality of fly ash, and the flyash water requirement that the coal vector is big is also big, and when mixing the system concrete; loose carbon granule wherein can adsorb admixture, reduces its water-reducing effect, influences intensity; reduce the concrete degree of mobilization, increase slump-loss.Loss on ignition is big more, and quality of fly ash is poor more.Loss on ignition has often determined a kind of quality of flyash.

Reducing the loss on ignition only way before this is exactly by selection by winnowing, stays and carefully goes slightly, because the carbon content in the thin ash is low relatively, loss on ignition is also less relatively.But the cost of this method is exactly the grey resource that will waste 30-50%, the cinder behind the thin ash of selection by winnowing, on the contrary enrichment the carbon part that burns incompletely, and can only sell or be discharged into ash disposal area cheap.The fly ash in electric power plant that has is just because of the too high utility value of almost completely having lost in concrete of its loss on ignition, and can only be used for backfill, builds a dam, and added value is extremely low.

On the other hand, flyash is typical non-homogeneity material, the mechanism complexity of formation, and influence factor is many, and the quality parameter fluctuation is big.China power plant adopts the commonplace of cyclone furnace, even if some large power plants, the phenomenon of loss on ignition index exceeding standard also often appears in flyash.Because the fluctuation of quality of fly ash, enterprise just had only the way that adopts the increasing factor of assurance between concrete was given birth to, and reduced volume or replacement rate, the waste that has strengthened fly ash.

How to reduce the loss on ignition of flyash? how to improve the even matter degree of flyash product? this is two key issues that improve the flyash product quality.The finding report nearly all is the means of wishing by chemi-excitations such as alkali, vitriol at present, improves its activity, and reaching increases the volume of flyash in concrete, reduces the purpose of concrete cost.This method pros and cons technically aside from, but adopt chemi-excitation cost height, it then is a undisputable fact that quality stability (even matter degree) is difficult to control, the utilization of historical facts or anecdotes border is few, is difficult in the same way, forms product advantage.

Three, summary of the invention

The object of the present invention is to provide a kind of modified coal ash, under the situation that the flyash loss on ignition as raw material exceeds standard, make its loss on ignition meet the requirement of concrete mixing material as concrete mixing material.

Another object of the present invention provides the production technique of above-mentioned improvement flyash.

The object of the present invention is achieved like this: a kind of modified coal ash as concrete mixing material, it is characterized in that it mixes by flyash and as the levigate liquid slag that reduces loss on ignition and forms, and the mixed ratio of liquid slag is not more than 40%; The fineness of this mixture reaches the screen over-size of 45 tm screen less than 25%, and the loss on ignition of mixture is not more than 8%.

The screen over-size that the fineness of described mixture reaches 45 tm screen is little by 12%, and the loss on ignition of mixture is not more than 5%.

The screen over-size that the fineness of described flyash reaches 45 tm screen is not more than 8%, and the screen over-size that the fineness of liquid slag reaches 45 tm screen is not more than 15%.

Another object of the present invention is achieved in that a kind of preparation method of mixture of fly ash, carries out according to the following steps:

A) preparation of flyash: flyash through selection by winnowing or pulverizing, is made it fineness and meets the requirements;

B) preparation of liquid slag: with liquid slag through magnetic separation, dry to water content less than 1%, be crushed to fineness and meet the requirements;

C) take by weighing A in proportion) step flyash and B) the step liquid slag, the two is mixed as finished product; Wherein the incorporation of liquid slag requires to decide according to the loss on ignition of mixture.

Each fuel-burning power plant is because all multifactor influences such as the type of the processing of the source of coal, coal dust, boiler, power plant load, the controls of incendiary parameter, and the loss on ignition index of flyash is widely different.We can not make power plant change coal variety just to the loss on ignition that reduces flyash or change boiler.Its application in concrete that flyash has exceeded standard serious overslaugh because of loss on ignition is too high, the flyash that exceeds standard for loss on ignition finds new outlets, and the loss on ignition that reduces flyash is the problem of pendulum in face of us.

The inventor has found the method that reduces the flyash loss on ignition through groping research, experiment repeatedly: it is that higher flyash carries out modification and handles that another kind of discharge-liquid slag of utilizing power plant self exceeds standard to loss on ignition.Liquid slag is the product of molten state furnace bottom slag quenching in water, and it exists with the particle form of glassy phase, and its chemical composition is identical with flyash, but loss on ignition is almost nil, and activity is higher than flyash.The levigate mixing with the higher flyash of loss on ignition by a certain percentage to the certain fineness of liquid slag carried out modification and handle, make the loss on ignition of mixture reach the GB requirement, simultaneously, the overall activity of mixture and homogeneity all are better than single pulverized coal dregs product.It is compound that the higher flyash of levigate liquid slag and loss on ignition carries out big volume, can be easily be controlled at the flyash loss on ignition after compound that (I level ash is not more than 5%, and II level ash is not more than 8% in the scope that needs.After tested, mix the flyash of liquid slag (incorporation≤40), can make the ultimate compression strength of concrete goods improve 3-5MPa, the liquid slag incorporation is high more, and ultimate compression strength improves many more.

One aspect of the present invention is to make the loss on ignition reduction after treatment of the too high flyash of loss on ignition to satisfy the requirement of concrete mixing material, has improved the use value of this part flyash, also makes this part flyash be unlikely to become waste residue and contaminate environment; The present invention has found new outlet, new purposes to liquid slag.Liquid slag from power plant only partly is used for cement industry at present, and the overwhelming majority is to be transported to the slag field to stack, and has both increased cost, again serious environment pollution.Therefore, the present invention with utilization of waste material, turn waste into wealth, have the huge social economic benefit.

Four, embodiment

Modified coal ash of the present invention mixes by flyash and as the levigate liquid slag that reduces loss on ignition and forms, and the mixed ratio of liquid slag is not more than 40%; The screen over-size that the fineness of this mixture (II level ash) reaches 45 tm screen is less than 25%, and the loss on ignition of mixture is not more than 8%.

The screen over-size that the fineness of said mixture (I level ash) reaches 45 tm screen is less than 12%, and the loss on ignition of mixture is not more than 5%.

The preparation method of modified coal ash of the present invention, carry out according to the following steps:

B) preparation of liquid slag: with liquid slag through magnetic separation, dry to water content less than 3%, preferably less than 1%, be crushed to fineness and meet the requirements;

C) take by weighing A in proportion) step flyash and B) the step liquid slag, the two is mixed as finished product (flyash and liquid slag should not adopt the mode of mix grinding); Wherein the incorporation of liquid slag requires to decide according to the loss on ignition of mixture.

The mixed ratio of liquid slag should not can cause excreting water phenomenon too much greater than 40%.The need water of levigate liquid slag is not more than 98% than generally, can play reduction need water ratio so mix the levigate liquid slag of certain proportion (〉=15%) in the bigger II level flyash of need water, improves the positive effect of compressive strength rate.The purpose of liquid slag magnetic separation is for deironing, although in the related standards of concrete mixing material iron is not stipulated that iron content can influence the concrete quality for a long time in the concrete.The fineness of liquid slag (45 μ m screen over-sizes are not more than 15%) is greater than the fineness (45 μ m screen over-sizes are not more than 8%) of pulverized coal dregs, is through experiment relatively and determine, the problem of economic aspect has been considered in the requirement that it has satisfied technical elements again.

Present method can be used in following situation:

One, carries out levigate processing powder coal ash with the former ash of power plant, when loss on ignition is higher;

Two, extract thin ash back, cinder (loss on ignition is severe overweight often) is carried out levigate and mixes liquid slag and do modification and handle, make it meet the specifications and require and be used with air blast process;

Three, during local fly ash in electric power plant inferior quality (loss on ignition is higher), with the levigate liquid slag of other factory to its carry out modification handle, to improve quality;

Four, during the qualified but resource shortage of local quality of fly ash, be used to increase output (having improved compressive strength rate simultaneously).

Claims

1. the modified coal ash as concrete mixing material is characterized in that, it mixes by flyash and as the levigate liquid slag that reduces loss on ignition and forms, and the mixed ratio of liquid slag is not more than 40%; The fineness of this mixture reaches the screen over-size of 45 tm screen less than 25%, and the loss on ignition of mixture is not more than 8%.

2. modified coal ash according to claim 1 is characterized in that, the fineness of described mixture reaches the screen over-size of 45 tm screen less than 12%, and the loss on ignition of mixture is not more than 5%.