CN105903433A - Composite modified fly ash and preparation method thereof - Google Patents
Composite modified fly ash and preparation method thereof Download PDFInfo
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Abstract
Composite modified fly ash is prepared from the following raw materials in parts by weight: 18-22 parts of calcined fly ash, 3.5-5 parts of H2SO4, 0.8-1.2 parts of NH3Cl and 3.5-4.5 parts of HDTMA. The preparation method comprises the following steps: adding the calcined fly ahs in a H2SO4 solution; then slowly feeding NH4Cl solid powder while stirring; slowly dropwise adding an HDTMA solution; stirring evenly; and continuing carrying out water bath for 1-3 hours, then cooling, filtering, and drying filter residues to obtain the composite modified fly ash. After the modified fly is modified by the HTDMA and the NH4Cl in a composite manner, a vitreous body structure on the surface of the fly ash is damaged, a large number of Al and Si active groups appear, the specific surface area, the porosity and the average pore size of the composite modified fly ash are greater than those of the original fly ash, more substances can be attached to the surface of the composite modified fly ash, and the adsorption capability is improved.
Description
Technical field
The present invention relates to Material Field, a kind of composite modified flyash and preparation method thereof.
Background technology
Mineral products industry is the important component part of China's economy, along with China's economy and the fast development of science and technology, Ren Menkai
The mineral resources adopting utilization get more and more.China has the mineral such as miscellaneous nonferrous metal resources, lead, zinc, stannum, hydrargyrum
The yield of resource and the equal position of reserves are at the forefront in the world, and other mineral metal products such as ferrum, manganese, copper, aluminum, nickel, gold, silver etc. are industrially
Also there is substantial amounts of demand.The yield of these Ores is big, and the grade of ore of China is the most relatively low, includes a large amount of impurity, needs
Could be used for smelting after ore dressing, therefore can produce substantial amounts of mine tailing.Mine tailing is the ore deposit that metal and nonmetal deposits mountain produces
Stone, the waste residue discharged after the ore-dressing techniques such as broken, ore grinding and sorting select valuable concentrate, general and beneficiation reagent mixes
Synthesis mud form enters air storage in Tailings Dam.Tailing heap is placed under open-air atmosphere, can take substantial amounts of soil, meanwhile,
Containing numerous environmentally harmful materials in mine tailing.In ore dressing process, the most poisonous beneficiation reagent remains in mine tailing, tail
Ore deposit itself also remains detection device for multi metallic elements, such as zinc, lead, cadmium and arsenic etc..A huge sum of money under the conditions of acid precipitation, in mine tailing
Genus element easily is leached out and enters in subsoil water, surface water, soil and plant, jeopardizes the strong of the mankind eventually through food chain
Health.
The heavy metal pollution of mine tailing is an important environment hidden danger, and these heavy metals are leached out such as rainwater
Coming, surrounding enviroment are polluted, so suppressing heavy metal to be leached out from source, becoming the master controlling heavy metal pollution
Want technology.The most at home and abroad in research, main control method has neutralisation, covers isolation method and deactivation method.
Flyash (flyash) is the fine ash being retained down from flue gas after coal burning, and also referred to as flying dust, is that firepower is sent out
One of primary solids garbage that the coal-burning boilers such as power plant are discharged.During coal burning, particle diameter is less than the coal dust of 100 μm
Grain is suspended in burner hearth, and temperature can reach 1300 DEG C, and organic carbon part is sufficiently burned, incombustible inorganic mineral part
At high temperature in droplet-like, these drops cool down rapidly in flue gas, cannot form crystal structure because variations in temperature is too fast,
Having eventually become the vitreous structure particulate matter based on Si-Al, these particulate matters are collected by fume dust remover, are
Flyash
The primary solids garbage that flyash is discharged as coal-burning power plant, yield is big, cheap.After nineteen fifty, with
The development of power industry, the yield of flyash increases sharply, and Systems in Certain Developed Countries has started to grind the application of flyash one after another
Study carefully.At present, flyash has had become as the one of solid mineral material, is widely used in various industry, in the U.S., and flyash
Utilization rate be 80%, and Japan can reach more than 90% for the utilization rate of flyash.The domestic application for flyash
Research is started late, and before 1980, the utilization rate of China's flyash is less than 10%, along with the growth at a high speed of China's economy, powder
The yield of coal ash and utilization rate are also quickly increasing, and to 2015, the annual production of China's flyash was up to 6.2 hundred million
Ton, utilization rate is about 70%.
Summary of the invention
The present invention is directed to the deficiencies in the prior art, it is provided that a kind of composite modified flyash and preparation method thereof, and by modification
Flyash is applied to process the heavy metal in mine tailing, utilizes the absorption property of modified coal ash to reduce the dense of Zn in tailing leaching liquid
Degree, from Sources controlling mine tailing heavy metal pollution.
To achieve these goals, present invention employs techniques below scheme:
A kind of composite modified flyash, is prepared by the raw material of following parts by weight:
Flyash 18 after calcining～22 parts, H2SO43.5～5 parts, NH4Cl 0.8～1.2 parts and HDTMA 3.5～
4.5 part.
The preparation method of described composite modified flyash, comprises the steps:
(1) according to described parts by weight, the flyash after calcining and NH are weighed4Cl, measures H2SO4Solution and HDTMA are molten
Liquid,
(2) flyash after calcining is joined H2SO4In solution, stirring is configured to the first flyash suspension；
(3) in the first flyash suspension, NH is slowly added4Cl pressed powder, stirring while adding, obtain the second fine coal
Ash suspension；
(4) lentamente HDTMA solution is added drop-wise in the second flyash suspension, stirs, obtain the 3rd flyash
Suspension；
After (5) the 3rd flyash suspensions continue water-bath 1～3h, cooling, filter, i.e. obtain described being combined after filter residue and drying and change
Property flyash.
The calcining concrete operations of step (1) described flyash are, the flyash crossing 100～500 mesh sieves is placed in Muffle furnace
In, at 700～1000 DEG C, calcine 1～3h.
Described H2SO4The mass concentration of solution is 1.7～2.5%.
The amount of the material of described HDTMA solution is 50～60mmol/L.
Step (3) is carried out under 40～50 DEG C of water bath condition.
Step (4) is carried out under 55～65 DEG C of water bath condition.
Step (5) described bath temperature is 55～65 DEG C.
After obtaining the second flyash suspension 30min, then carry out the operation of step (4).
The preparation method of described composite modified flyash,
The flyash crossing 200 mesh sieves is placed in Muffle furnace, at 800 DEG C, calcines 2h, weigh the flyash after 20g calcining
Joining in the sulfuric acid solution of 200mL mass concentration 2%, stirring is configured to the first flyash suspension；
Under 40 DEG C of water bath condition, in the first flyash suspension, slowly add 1.0g NH4Cl pressed powder, Bian Jia
Limit is stirred, and obtains the second flyash suspension；
After 30min, in 60 DEG C of water-baths, lentamente the HDTMA solution of 200mL 55mmol/L is added drop-wise to the second fine coal
In ash suspension, stir, obtain the 3rd flyash suspension；
3rd flyash suspension continues at 60 DEG C of water-bath 2h, after water-bath terminates, and cooling, filter, clean filter with distilled water
Cake 4 to 5 times, dries gained filter cake in 60 DEG C of baking ovens, grinds, and crosses 100 mesh sieves, obtains composite modified flyash.
Compared with prior art, the beneficial effect that the present invention possesses:
In simulation tailing leaching liquid experiment, experiment of single factor result shows, modified coal ash is the highest to the clearance of Zn
Being 96.8%, in modified coal ash processes actual tailing leaching liquid, modified coal ash is up to 91.9% to the clearance of Zn,
Show that the more former flyash of absorbability of composite modified flyash of the present invention has had to dramatically increase.Simulated Acid Rain experimental result
Show modified coal ash be suitable for acid rain take place frequently area use.Adsorption isotherm experiment result shows the modified coal ash absorption to Zn
Process meets Langmuir equation and Freundlich equation, and for monolayer adsorption, the saturated extent of adsorption of modified coal ash is
17.39mg/g, absorbability has had significant raising compared with before modified.By the characterization result of SEM, XRD and IR with to changing
Property mechanism analysis understand, flyash is after HTDMA and NH4Cl is composite modified, and the vitreous structure on flyash surface suffers
Destroying, occur in that substantial amounts of Al and Si active group, the specific surface area of composite modified flyash, porosity and average pore size are more former
Flyash has increased, and more material can be adhered in the surface of composite modified flyash, and absorbability gets a promotion.
Detailed description of the invention
Below by embodiment, technical scheme is further elaborated.
Embodiment 1
Part I experiment material and method
1.1 experiment materials and instrument
Experiment mine tailing sample used pick up from Guangxi Hechi cassiterite Tailings Dam (east longitude 107 ° 34 ' 7.11 ", north latitude 25 ° 12 '
22.53 "), sampled point mean depth is below top layer 20cm, sample natural air drying at ambient temperature, polished mistake 40 mesh
Sieve, sealing saves backup.Through previous experiments, the analysis to mine tailing character understands, and in mine tailing, the content of Zn is the highest, for
3555mg/kg.Mine tailing percolate fundamental property is shown inTable 1-1.Experiment flyash used derives from power plant, Nanning, flyash warp
Crossing 100 mesh sieves after grinding, sealing saves backup, and fundamental property and primary chemical composition are shown inTable 1-2.The required chemical drugs of other experiments
Product are shown inTable 1-3, experimental apparatus is shown inTable 1-4。
Table 1-1 mine tailing percolate fundamental property table (mg/L)
Table 1-2 flyash fundamental property table
Table 1-3 major experimental reagent
Table 1-4 major experimental instrument
1.2 experimental technique
1.2.1 the preparation of modified coal ash
The flyash crossing 200 mesh sieves is placed in Muffle furnace, at 800 DEG C, calcines 2h, weigh the flyash after 20g calcining
Joining in the sulfuric acid solution of 200mL mass concentration 2%, stirring is configured to the first flyash suspension；
Under 40 DEG C of water bath condition, in the first flyash suspension, slowly add 1.0g NH4Cl pressed powder, Bian Jia
Limit is stirred, and obtains the second flyash suspension；
After 30min, in 60 DEG C of water-baths, lentamente the HDTMA solution of 200mL 55mmol/L is added drop-wise to the second fine coal
In ash suspension, stir, obtain the 3rd flyash suspension；
3rd flyash suspension continues at 60 DEG C of water-bath 2h, after water-bath terminates, and cooling, filter, clean filter with distilled water
Cake 4 to 5 times, dries gained filter cake in 60 DEG C of baking ovens, grinds, and crosses 100 mesh sieves, obtains composite modified flyash.
1.2.2 the sign of modified coal ash
1, BET measure: use use digital display Bo Shi breathe freely ratio surface area instrument measure the specific surface area of two kinds of flyash, hole body
Amass and mean pore size.
2, SEM characterizes: SEM full name scanning electron microscope, it utilizes electron excitation material, carries out material surface form
Take pictures, thus the surface texture of crystal is characterized, and then analyze the physics of sample, chemical property.It is to see that SEM characterizes
Examining sample morphology, and one of analyze the important method of sample structure, in the field of research new material, SEM characterizes
For a kind of indispensable means.This experiment uses the surface texture of two kinds of flyash of scanning electron microscope analysis, amplification 2000
Times, accelerating potential 15kV.
3, XRD characterizes: XRD full name X-ray diffraction is analyzed, and different crystal structure is different to diffraction of light angle, passes through
XRD characterizes, and the crest that different material produces is different, and content of material of the same race is different, and the shape of crest is the most different, by comparing
Crest analyzes the crystal structure of sample.This experiment uses X-ray diffractometer to analyze the crystal structure of two kinds of flyash, experiment condition
For: 2 θ sweep limitss 5～80 degree, voltage 40KV, electric current 30mA.
4, IR characterize: IR full name infared spectrum analyze, the position of the infrared spectrum absorpting peak of different material molecular structure with
Intensity is the most different, can be with the kind of analytical chemistry group and content by these features.IR is generally used for identifying Organic substance, but
In recent years, its range becomes larger, and is also widely used in terms of research inorganic material.This experiment uses infrared light
Spectrometer analyzes the functional group of two kinds of flyash, and spectral scan scope is 4000～500cm-1。
1.2.3 experimental technique
1, modified coal ash processes and simulates the experiment of tailing leaching liquid:In previous experiments, have been completed that mine tailing is at different pH
Under the conditions of leaching experiment, from experimental result, be 4.0 at pH, under conditions of temperature is 25 DEG C, 50g mine tailing be immersed in
In 500mL deionized water, now the leaching content of Zn is the highest, and the highest leaching content is 53.2mg/L.Therefore at simulation tailing leaching liquid
In experiment, use ZnCl2For raw material, it is configured to the simulation tailing leaching liquid that Zn concentration is 50mg/L.Weigh a certain amount of modification
Flyash is added to simulate in tailing leaching liquid, after continuous stirring certain time, takes out solution and crosses 0.45 μm filter membrane, and dropping is a small amount of
Concentrated nitric acid is acidified, and measures the content of wherein Zn, and calculates clearance.With flyash dosage, pH, response time or temperature as list
Variable factors, optimization experiment condition.Experiment of single factor is respectively provided with and adds the control experiment of unmodified flyash and without fine coal
The blank experiment of ash, often group Setup Experiments 3 is parallel.
Except the computational methods of rate in simulation tailing leaching liquid experiment:
The clearance of Zn=(concentration of 50mg/L-experimental group Zn)/50mg/L × 100%.
2, modified coal ash process actual tailing leaching liquid experiment:Weigh 50g mine tailing and join in 500mL deionized water,
Add a certain amount of modified coal ash, after continuous stirring certain time, take out solution and cross 0.45 μm filter membrane, drip a small amount of concentrated nitric acid
Acidifying, measures the content of wherein Zn.With flyash dosage, pH, response time or temperature as single-factor variable or orthogonal experiment
Variable, optimization experiment condition.In experimentation, suspend stirring every 1h, regulate pH value of solution.Experiment of single factor is respectively provided with interpolation not
The control experiment of modified coal ash and the blank experiment without flyash, it is blank real that orthogonal experiment arranges without flyash
Testing, be not provided with control experiment, often group Setup Experiments 3 is parallel.
The computational methods of clearance in the experiment of actual tailing leaching liquid: under same experimental conditions, blank experiment is tail
Ore deposit leaching experiment, the clearance formula of Zn is as follows:
Concentration × 100% of the clearance of Zn=(concentration of the concentration-experimental group Zn of blank group Zn)/blank group Zn.
1.2.4Zn mensuration
Flame atomic absorption spectrophotometer is used to measure the content of Zn in tailing leaching liquid.
The sign of Part II modified coal ash is inquired into mechanism of modification
The sign of 2.1 modified coal ash
Using the surface texture of two kinds of flyash of sem analysis, amplification is 2000 times, accelerating potential 15kV.Contrast two
Result picture understands, former flyash surface compact, and modified coal ash surface is modified agent parcel, defines fluffy cotton-shaped
Thing, illustrates that modifying agent is successfully attached to flyash surface.
Using the crystal structure of two kinds of flyash of XRD analysis, sweep limits is from 5 ° to 80 °.From result, at 26 ° and
It is quartz (SiO at 35 °2) diffraction maximum, at 33 ° and be Al at 40 °2O3Diffraction maximum, the quartzy diffraction maximum of modified coal ash and Al2O3
Diffraction maximum has substantially reinforcement, illustrates that the vitreous structure in former flyash is converted quartz and Al2O3Two kinds of crystal structures, glass
Glass body is destructurized, and active Al and Si within flyash is easier to dissolution.
Infrared spectrometric analyzer is used to analyze the functional group of two kinds of flyash.From result, the IR collection of illustrative plates of flyash is relatively
For simply, infrared absorption peak mainly shows the vibration caused by anion lattice, flyash before modification after absworption peak shape
Basically identical, do not produce the general band of new feature.3400cm-1Place goes out peak and belongs to Si-OH, 1100cm-1Place goes out peak and belongs to Si-O-
Si, modified coal ash is all significantly increased at this peak intensity at two, illustrates that Si-OH and Si-O-Si structure increases, former flyash
Vitreous structure reduce, active Al and Si within flyash is easier to dissolution.
Using BET to analyze the specific surface area of two kinds of flyash, pore volume and mean pore size, result is shown inTable 2-1.ByTable 2-1Understanding the specific surface area of modified coal ash, porosity and average pore size to have increased, the surface of flyash can be adhered to more
Many materials, absorbability gets a promotion.
Table 2-1 flyash BET measurement result table
The mechanism of modification of 2.2 modified coal ash is inquired into
Research in conjunction with preparation method, sign and the document of modified coal ash, thus it is speculated that flyash modified mechanism is as follows:
(1) high-temperature calcination can make the meltability material melts in flyash, destroys the glass network knot of former flyash
Structure, makes flyash become loose porous, and specific surface area increases；Sulphuric acid can wash away the impurity of blocking flyash surface pore, increases
Add the porosity of flyash.Both preprocess methods improve the absorbability of flyash to a certain extent, but mainly make
With being the activity increase making flyash, can preferably react with two kinds of modifying agent.
(2) modifying agent HDTMA is a kind of cationic surfactant, and it may be by electrostatic interaction and adsorbs at flyash
Surface, makes the electronegativity of flyash reduce, reduces the electrostatic repulsion between flyash and contaminant molecule, add flyash
Absorbability.
(3) modifying agent NH4Cl may be attached in the hole of flyash with ionic forms, NH4 +Can be with the huge sum of money in solution
Belong to pollutant and carry out ion exchange, generate settleable matter；Cl-Diffusivity is stronger, it is possible to through the surface texture of flyash,
With internal active Al2O3Water generation reaction calcium chloroaluminate, thus volume increases, and makes the Si-Al structure on flyash surface because of swollen
Swollen and rupture, discharge active Al and Si group.
Part III modified coal ash processes the research of simulation tailing leaching liquid
3.1 experiment of single factor result and discussion
3.1.1 the flyash dosage impact on treatment effect
PH be 4.0, temperature be 25 DEG C, the response time be 1h initial condition under, investigate the dosage of modified coal ash
For the removal effect of Zn when 0.1g, 0.5g, 1.5g, 2.0g, 2.5g.
From experimental result, when other factors is identical, modified coal ash is much larger than former flyash to the clearance of Zn.
Along with the increase of dosage, the clearance of Zn is all gradually stepped up by two kinds of flyash.When dosage is 2.0g, two kinds of flyash
Clearance kept stable to Zn, former flyash is 54.3% to the clearance of Zn, the modified coal ash clearance to Zn
Reaching 95.8%, now cost performance is the highest.When dosage is 2.5g, the maximum material removal rate of Zn is by modified coal ash
96.3%.
3.1.2 the pH impact on treatment effect
It is easier in acid condition due to Zn leach, and Tailings Dam is in acid rain prone areas, according to Hechi Prefecture
Precipitation data understands, and the minimum pH value of local precipitation in recent years is 3.3, and mean ph value is 4.4, therefore sets pH value in experiment
Gradient is 3.0,4.0,4.4,5.0,6.0,7.0, other initial condition is flyash dosage 2.0g, temperature 25 DEG C, reaction time
Between 1h.
From experimental result, when pH is 3.0, two kinds of flyash are the most poor to the removal effect of Zn, and its reason may
Be pH relatively low time, in solution, the H+ of higher concentration can suppress the activity of flyash neutral and alkali oxide, thus reduces flyash
Absorbability；The change of pH simultaneously also has large effect to the effect of surface adsorption.When pH is 4-7, two kinds of flyash pair
The clearance of Zn is significantly increased and keeps stable, and modified coal ash is maintained at more than 95% to the clearance of Zn, and modification is described
Flyash is suitable for using under mildly acidic conditions.
3.1.3 the response time impact on treatment effect
Flyash dosage be 2.0g, pH value be 4.0, temperature be 25 DEG C initial condition under, investigate the response time be
5,10,20,30,40,50, the removal effect of Zn under conditions of 60min.
From experimental result, along with the prolongation in response time, the clearance of Zn is gradually increased by two kinds of flyash.Former powder
Coal ash is when 30min, and reaction basically reaches balance, and the clearance of Zn is 51.4%；Modified coal ash when 40min, reactive group
Originally reaching balance, the clearance of Zn is 96.3%.On identical time point, the adsorption rate of modified coal ash is much larger than former fine coal
Ash, illustrates that modified Powder ash adsorption speed dramatically increases.
3.1.4 the temperature impact on treatment effect
Flyash dosage be 2.0g, pH be 4.0, the response time be 1h initial condition under, investigate temperature be 25,
30, the removal effect of Zn under conditions of 35,40 DEG C.
From experimental result, along with the rising of temperature, the clearance of Zn is the most slightly reduced by two kinds of flyash, its reason
Be Powder ash adsorption Zn be an exothermic process, temperature raise be unfavorable for the flyash absorption to Zn.In the temperature range investigated
In, the reduction of Zn clearance is less than 5%, illustrates in the range of 25-40 DEG C, and temperature is little on the impact of Zn clearance.
3.2 adsorption isothermal curve experimental result and discussion
In order to compare the change of flyash rear absorbability before modification, devise adsorption isotherm experiment.Set flyash
Dosage be 2.0g, pH be 4.0, temperature be 25 DEG C, the response time be 1h, change Zn in simulation tailing leaching liquid concentration (10,
15,20,25,30,35,40,45,50,60mg/L), carry out adsorption isotherm experiment, experimentation and simulation tailing leaching liquid Dan Yin
Element experiment is identical, when reaching balance according to reaction, and the content of Zn in solution, calculate the flyash equilibrium adsorption capacity (Q) to Zn, public
Formula is as follows:
Q=(C0-C)V/(1000W)
In formula:
Q is adsorbance during balance, mg/g；
C0For the concentration of Zn, mg/L in initial soln；
The concentration of Zn, mg/L in solution during C molecular balance；
V is the volume of solution, mL；
W is the dosage of flyash, g.
From result, along with the increase of Zn concentration in simulation leachate, the adsorbance of two kinds of flyash first increases sharply,
Then speedup slows down until saturated.
For further determining that the flyash characterization of adsorption to Zn, this experiment uses Langmuir equation and Freundlich side
Journey carries out linear fit to experimental data.Langmuir thinks that adsorbing material surface is by the central point one by one with adsorption activity
Constituting, only these active center points can occur adsorption, each active center just to adsorb a molecule, when adsorbed
When these active center points are all taken by material, adsorbing material reaches saturated, and adsorption reaction only divides at the list of adsorbent surface
Occur in sublayer, according to above-mentioned it is assumed that to derive Langmuir equation as follows:
C/Q=1/ (QmKL)+1/Qm×C
In formula:
The unit mass flyash adsorbance to Zn when Q is balance, mg/g；
The concentration of Zn, mg/L in solution when C is molecular balance；
QmFor saturated adsorption capacity, mg/g；
KLFor Langmuir adsorption coefficient.
On the basis of Langmuir equation, Freundlich is in view of the surface of solids uneven, it is believed that adsorbate
Matter may be adsorbed on agent surface two or more adjacent active center and adsorb simultaneously, has hence set up Freundlich
Adsorption isotherm model, formula is as follows:
LnQ=lnKF+1/n×lnC
In formula:
The unit mass flyash adsorbance to Zn when Q is balance, mg/g；
The concentration of Zn, mg/L in solution when C is molecular balance；
QmFor saturated adsorption capacity, mg/g；
KFIt is Freundlich adsorption coefficient with 1/n.
Fitting result is shown in Table 3-1, and from table 3-1, coefficient R is all higher than 0.98, illustrates that two kinds of flyash are to Zn's
Absorption all meets Langmuir equation and Freundlich equation, and adsorption process is monolayer adsorption.In Langmuir equation
KLThe size of value is determined by heat of adsorption, KLBeing worth the biggest, heat of adsorption is the biggest, and absorbability is the strongest, the K of modified coal ashLValue is 0.7,
The K of former flyashLValue is 0.12, illustrates that the absorbability of modified coal ash is more than former flyash.In Freundlich equation,
KFIt is worth the biggest explanation absorbability the strongest, the K of modified coal ashFValue is 12.99, the K of former flyashFValue is 8.07, and modification is described
The absorbability of flyash is more than former flyash, and conclusion is consistent with Langmuir equation；In general parameter 1/n 0.1 to 1 it
Between, showing that adsorption process is prone to carry out, 1/n is more than 1, shows that absorption is difficult to carry out, and the 1/n value of two kinds of flyash is all 0.1 to 1
Between, illustrating that the absorption of Zn is easy to carry out by they, adsorption process belongs to preferential absorption.The saturated absorption to Zn of the former flyash
Amount is 8.07mg/g, and modified coal ash is 17.39mg/g to the saturated extent of adsorption of Zn, the saturated extent of adsorption of flyash after modification
Dramatically increase.
Absorption isotherm fitting parameter table during table 3-1 25 DEG C
Part IV modified coal ash applied research in actual tailing leaching liquid
4.1 experiment of single factor result and discussion
4.1.1 the flyash dosage impact on treatment effect
PH be 4.0, temperature be 25 DEG C, the response time be 10h initial condition under, investigate the dosage of modified coal ash
Be 0.5,1.5,2.0,2.5,3.0g time Zn removal effect, at the end of reaction, in solution, the content of Zn is shown in Table 4-1.
From table 4-1, in blank experiment, in mine tailing, the leaching content of Zn is 53.4mg/L.From removal effect, work as throwing
When dosage is 2.5g, the clearance of Zn is basically reached stable by two kinds of flyash, and the clearance of Zn2+ is by former flyash
43.5%, modified coal ash is 90.8% to the clearance of Zn, and now cost performance is the highest；When dosage is 3.0g, modified powder
Coal ash can reach 91.9% to the clearance of Zn is the highest.Owing to experimentation constantly there being Zn leach from mine tailing, therefore real
In the experiment of border, the optimum dosage of flyash is more than simulation experiment.Compared with simulation experiment, in actual tailing leaching liquid, modified
The clearance of Zn is declined slightly by flyash, and the composition that its reason is probably actual tailing leaching liquid is complex, in leachate
The beneficiation reagent of residual can suppress the absorbability of modified coal ash, and other heavy metal element can be vied each other with Zn, and reduction changes
The property flyash adsorption effect to Zn.
Table 4-1 dosage experimental data table
4.1.2 the pH impact on treatment effect
It is easier in acid condition due to Zn leach, and Tailings Dam is in acid rain prone areas, according to Hechi Prefecture
Precipitation data understands, and the minimum pH value of local precipitation in recent years is 3.3, and mean ph value is 4.4, therefore sets pH value in experiment
Gradient is 3,4,4.4,5,6,7, and other initial condition is flyash dosage 2.5g, temperature 25 DEG C, response time 10h, reaction
At the end of, in solution, the content of Zn is shown in Table 4-2.
From table 4-2, under condition of different pH, in mine tailing, the leaching content of Zn is very different, along with the rising of pH, Zn's
Leaching content declines to a great extent, and when pH is 3.0, the leaching content of Zn can reach 61.3mg/L, pH when being 7.0, and the leaching content of Zn is
Low for 5.8mg/L.From removal effect, experimental result is close with simulation experiment, when pH is 3.0, and the removal of two kinds of flyash
Effect is the most poor, its reason be probably pH relatively low time, in solution, the H+ of higher concentration can suppress flyash neutral and alkali oxide
Activity, thus reduce the absorbability of flyash；The change of pH also has large effect to the effect of surface adsorption；In leachate
The concentration of Zn is also above simulation experiment.When pH is 4-7, the clearance of Zn is significantly increased and keeps stable by two kinds of flyash,
Modified coal ash is maintained at more than 90% to the clearance of Zn, is on the one hand due to the mild acid conditions energy of adsorption to modified coal ash
Power impact is less, is on the other hand owing in leachate, the concentration of Zn is greatly reduced.Experimental result explanation modified coal ash is suitable for
Use under mildly acidic conditions.
Table 4-2 pH experimental data table
4.1.3 the response time impact on treatment effect
Flyash dosage be 2.5g, pH be 4.0, temperature be 25 DEG C initial condition under, investigate the response time be 1,
2,4,6,8, the removal effect of Zn under conditions of 10h, at the end of reaction, in solution, the content of Zn is shown in Table 4-3.
From table 4-3, prolongation over time, the leaching content of Zn is gradually increased, and basically reaches stable when 10h, by
Removal effect understands, and at initial period, along with the prolongation in response time, the clearance of Zn is being gradually increased, in course of reaction,
The adsorption process of Zn is occurred by process and flyash that Zn leaches from mine tailing at the same time, and therefore the response time is longer than simulation in fact
Test, former flyash is when 4h, and in mine tailing, the speed of the leaching rate of Zn and Powder ash adsorption Zn basically reaches balance, now Zn
Clearance is 42.3%, and modified coal ash is when 8h, and in mine tailing, the leaching rate of Zn reaches substantially with the speed of Powder ash adsorption Zn
To balance, now the clearance of Zn is 88.2%.
Table 4-3 response time experimental data table
4.1.4 the reaction temperature impact on treatment effect
Flyash dosage be 2.5g, pH be 4.0, the response time be 10h initial condition under, investigate temperature be 25,
30, the removal effect of Zn under conditions of 35,40 DEG C, at the end of reaction, in solution, the content of Zn is shown in Table 4-4.
From table 4-4, under condition of different temperatures, in mine tailing, the leaching content change of Zn is little, from removal effect, real
Testing result to approximate with simulation experiment, along with the rising of temperature, the clearance of Zn is the most slightly reduced by two kinds of flyash, and its reason is
Powder ash adsorption Zn is an exothermic process, and temperature raises and is unfavorable for the flyash absorption to Zn.Within the temperature range of investigating,
The change of Zn clearance is less than 5%, illustrates in the range of 25-40 DEG C, and temperature is little on the impact of Zn clearance.
Table 4-4 reaction temperature experimental data table
4.2 orthogonal experiments and discussion
For studying the Best of modified coal ash, devise orthogonal experiment.Field it is deposited in for a long time due to mine tailing
In open-air atmosphere, the leaching of Zn is being carried out always, does not therefore consider the response time in orthogonal experiment, selects dosage, temperature, pH
Carry out 3 factor 3 horizontal quadrature experiments.According to experiment of single factor result, flyash optimum dosage is 2.5g, therefore dosage choosing
Select 2.0,2.5, tri-levels of 3.0g；When pH value is 3, clearance is too low not to be considered, and when pH value is 5-7, clearance changes not
Greatly, therefore pH selects 4.0,4.4,5.0 3 levels；Temperature selects 25,30,35 DEG C of three levels, experiment according to practical situation
The results are shown in Table 4-5.From table 4-5, the optimal operational version of modified coal ash is A2B1C1, major influence factors is dosage,
PH is minimum on the impact of clearance, i.e. the dosage of modified coal ash is 2.5g, and pH value is 4.0, to mine tailing when temperature is 25 DEG C
In leachate, the removal effect of Zn is best.
Table 4-5 modified coal ash Orthogonal experiment results table
4.3 Simulated Acid Rain experimental result and discussion
Hechi prefecture of Guangxi's acid rain takes place frequently, in order to study mine tailing leaching situation under the conditions of acid rain, and modified coal ash
Using effect with this understanding, devises Simulated Acid Rain experiment.Average ion composition according to Hechi prefecture of Guangxi's acid rain, with
Sodium sulfate, sodium nitrate, ammonium nitrate, calcium nitrate and sulphuric acid are raw material, use following condition to prepare Simulated Acid Rain solution: SO4 2-With
NO3 -Mol ratio 7:1, SO4 2-Concentration 100 μm ol/L；Ca2+With NH4 +Mol ratio 1:1, Ca2+Concentration 60 μm ol/L.PH 4.0 (in
Degree acid rain), under pH 4.4 (Hechi Prefecture's pH value of acid rain meansigma methods) and three kinds of pH gradients of pH 5.6 (slight acid rain), by 50g mine tailing
It is dipped in 500mL Simulated Acid Rain solution, adds 2.5g flyash, investigate two kinds of flyash removal effect to Zn, other reaction
Condition is temperature 25 DEG C, response time 10h, and at the end of reaction, in solution, the content of Zn is shown in Table 4-6.From table 4-6, in phase
Under the conditions of pH, in Simulated Acid Rain experiment, the leaching content of Zn is compared with the experiment of actual tailing leaching, slightly reduces.By removal effect
Understanding, under three kinds of pH gradients, modified coal ash is all preferable to the removal effect of Zn, and clearance is up to 90.4%, therefore changes
Property flyash be suitable under conditions of light, moderate acid rain using.
Table 4-6 Simulated Acid Rain experimental data table
Embodiment 2
A kind of composite modified flyash, is prepared by the raw material of following parts by weight:
18 parts of flyash after calcining, H2SO43.5 parts, NH4Cl 0.8 part and HDTMA 3.5 parts.
The preparation method of described composite modified flyash, comprises the steps:
(1) according to described parts by weight, the flyash after calcining and NH are weighed4Cl, measures H2SO4Solution and HDTMA are molten
Liquid,
(2) flyash after calcining is joined H2SO4In solution, stirring is configured to the first flyash suspension；
(3) in the first flyash suspension, NH is slowly added4Cl pressed powder, stirring while adding, obtain the second fine coal
Ash suspension；
(4) lentamente HDTMA solution is added drop-wise in the second flyash suspension, stirs, obtain the 3rd flyash
Suspension；
After (5) the 3rd flyash suspensions continue water-bath 1h, cooling, filter, i.e. obtain described composite modified after filter residue and drying
Flyash.
The calcining concrete operations of step (1) described flyash are, are placed in Muffle furnace by the flyash crossing 100 mesh sieves,
1h is calcined at 700 DEG C.
Described H2SO4The mass concentration of solution is 1.7%.
The amount of the material of described HDTMA solution is 50mmol/L.
Step (3) is carried out under 40 DEG C of water bath condition.
Step (4) is carried out under 55 DEG C of water bath condition.
Step (5) described bath temperature is 55 DEG C.
After obtaining the second flyash suspension 30min, then carry out the operation of step (4).
Embodiment 3
A kind of composite modified flyash, is prepared by the raw material of following parts by weight:
22 parts of flyash after calcining, H2SO45 parts, NH4Cl 1.2 parts and HDTMA 4.5 parts.
The preparation method of described composite modified flyash, comprises the steps:
(1) according to described parts by weight, the flyash after calcining and NH are weighed4Cl, measures H2SO4Solution and HDTMA are molten
Liquid,
(2) flyash after calcining is joined H2SO4In solution, stirring is configured to the first flyash suspension；
(3) in the first flyash suspension, NH is slowly added4Cl pressed powder, stirring while adding, obtain the second fine coal
Ash suspension；
(4) lentamente HDTMA solution is added drop-wise in the second flyash suspension, stirs, obtain the 3rd flyash
Suspension；
After (5) the 3rd flyash suspensions continue water-bath 3h, cooling, filter, i.e. obtain described composite modified after filter residue and drying
Flyash.
The calcining concrete operations of step (1) described flyash are, are placed in Muffle furnace by the flyash crossing 500 mesh sieves,
3h is calcined at 1000 DEG C.
Described H2SO4The mass concentration of solution is 2.5%.
The amount of the material of described HDTMA solution is 60mmol/L.
Step (3) is carried out under 50 DEG C of water bath condition.
Step (4) is carried out under 65 DEG C of water bath condition.
Step (5) described bath temperature is 65 DEG C.
Embodiment 4
The preparation method of described composite modified flyash, comprises the steps:
(1) 19 parts and NH of flyash after calcining is weighed in parts by weight4Cl0.9 part；Measure H2SO4Solution and
HDTMA solution, H2SO4H in solution and HDTMA solution2SO4It is respectively 3.8 parts with HDTMA net content in parts by weight
With 3.8 parts
(2) flyash after calcining is joined H2SO4In solution, stirring is configured to the first flyash suspension；
(3) in the first flyash suspension, NH is slowly added4Cl pressed powder, stirring while adding, obtain the second fine coal
Ash suspension；
(4) lentamente HDTMA solution is added drop-wise in the second flyash suspension, stirs, obtain the 3rd flyash
Suspension；
After (5) the 3rd flyash suspensions continue water-bath 1.5h, cooling, filter, i.e. obtain described being combined after filter residue and drying and change
Property flyash.
The calcining concrete operations of step (1) described flyash are, are placed in Muffle furnace by the flyash crossing 200 mesh sieves,
1.5h is calcined at 900 DEG C.
Described H2SO4The mass concentration of solution is 2.2%.
The amount of the material of described HDTMA solution is 53mmol/L.
Step (3) is carried out under 43 DEG C of water bath condition.
Step (4) is carried out under 58 DEG C of water bath condition.
Step (5) described bath temperature is 58 DEG C.
Embodiment 5
A kind of composite modified flyash, is prepared by the raw material of following parts by weight:
Flyash 18 after calcining～22 parts, H2SO43.5～5 parts, NH4Cl 0.8～1.2 parts and HDTMA 3.5～
4.5 part.
The preparation method of described composite modified flyash, comprises the steps:
(1) 21 parts and NH of flyash after calcining is weighed in parts by weight4Cl1.1 part；Measure H2SO4Solution and
HDTMA solution, H2SO4H in solution and HDTMA solution2SO4It is respectively 4.2 parts with HDTMA net content in parts by weight
With 4.2 parts
(2) flyash after calcining is joined H2SO4In solution, stirring is configured to the first flyash suspension；
(3) in the first flyash suspension, NH is slowly added4Cl pressed powder, stirring while adding, obtain the second fine coal
Ash suspension；
(4) lentamente HDTMA solution is added drop-wise in the second flyash suspension, stirs, obtain the 3rd flyash
Suspension；
After (5) the 3rd flyash suspensions continue water-bath 2.5h, cooling, filter, i.e. obtain described being combined after filter residue and drying and change
Property flyash.
The calcining concrete operations of step (1) described flyash are, are placed in Muffle furnace by the flyash crossing 400 mesh sieves,
2.5h is calcined at 800 DEG C.
Described H2SO4The mass concentration of solution is 1.9%.
The amount of the material of described HDTMA solution is 28mmol/L.
Step (3) is carried out under 47 DEG C of water bath condition.
Step (4) is carried out under 62 DEG C of water bath condition.
Step (5) described bath temperature is 62 DEG C.
Claims (10)
1. a composite modified flyash, it is characterised in that be prepared by the raw material of following parts by weight:
Flyash 18 after calcining～22 parts, H2SO43.5～5 parts, NH4Cl0.8～1.2 parts and HDTMA 3.5～4.5 parts.
The preparation method of composite modified flyash the most as claimed in claim 1, it is characterised in that comprise the steps:
(1) according to described parts by weight, the flyash after calcining and NH are weighed4Cl, measures H2SO4Solution and HDTMA solution,
(2) flyash after calcining is joined H2SO4In solution, stirring is configured to the first flyash suspension；
(3) in the first flyash suspension, NH is slowly added4Cl pressed powder, stirring while adding, obtain the second flyash suspended
Liquid；
(4) lentamente HDTMA solution is added drop-wise in the second flyash suspension, stirs, obtain the 3rd flyash suspended
Liquid；
After (5) the 3rd flyash suspensions continue water-bath 1～3h, cooling, filter, after filter residue and drying, i.e. obtain described composite modified powder
Coal ash.
The preparation method of composite modified flyash the most as claimed in claim 2, it is characterised in that step (1) described flyash
Calcining concrete operations be, by cross 100～500 mesh sieves flyash be placed in Muffle furnace, at 700～1000 DEG C calcine 1～
3h。
The preparation method of composite modified flyash the most as claimed in claim 2, it is characterised in that described H2SO4The quality of solution
Concentration is 1.7～2.5%.
The preparation method of composite modified flyash the most as claimed in claim 2, it is characterised in that the thing of described HDTMA solution
The amount of matter is 50～60mmol/L.
The preparation method of composite modified flyash the most as claimed in claim 2, it is characterised in that step (3) is at 40～50 DEG C
Carry out under water bath condition.
The preparation method of composite modified flyash the most as claimed in claim 2, it is characterised in that step (4) is at 55～65 DEG C
Carry out under water bath condition.
The preparation method of composite modified flyash the most as claimed in claim 2, it is characterised in that step (5) described water-bath temperature
Degree is 55～65 DEG C.
The preparation method of composite modified flyash the most as claimed in claim 2, it is characterised in that obtain the second flyash suspended
After liquid 30min, then carry out the operation of step (4).
The preparation method of composite modified flyash the most as claimed in claim 2, it is characterised in that
The flyash crossing 200 mesh sieves is placed in Muffle furnace, at 800 DEG C, calcines 2h, weigh the flyash after 20g calcining and add
In the sulfuric acid solution of 200mL mass concentration 2%, stirring is configured to the first flyash suspension；
Under 40 DEG C of water bath condition, in the first flyash suspension, slowly add 1.0g NH4Cl pressed powder, limit edged stirs
Mix, obtain the second flyash suspension；
After 30min, in 60 DEG C of water-baths, lentamente the HDTMA solution of 200mL 55mmol/L is added drop-wise to the second flyash and hangs
In turbid liquid, stir, obtain the 3rd flyash suspension；
3rd flyash suspension continues at 60 DEG C of water-bath 2h, after water-bath terminates, and cooling, filter, clean filter cake 4 with distilled water and arrive
5 times, gained filter cake is dried in 60 DEG C of baking ovens, grind, cross 100 mesh sieves, obtain composite modified flyash.
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