Method for detecting concentration of residual polyaluminum chloride and content of effective components in machine-made sand

Abstract

The invention discloses a method for detecting the concentration of residual polyaluminum chloride and the content of effective components in machine-made sand, which comprises the following steps of: establishing a database of double thresholds of a polyaluminum chloride standard aqueous solution under the conditions of different concentrations and different content of effective components on the basis of an S-V relation curve of a standard sample; fitting the database of the double thresholds of the polyaluminum chloride standard aqueous solution into a nonlinear curved surface formula; the method comprises the following steps: obtaining characteristic points V1 and V2 from an S-V relation curve of a to-be-detected sample, respectively substituting V1 and V2 into a nonlinear curved surface formula formed by fitting a database of double thresholds of a polyaluminum chloride standard aqueous solution, and obtaining the concentration phi and the effective component content Al of polyaluminum chloride in the to-be-detected sample in a manner of solving a nonlinear equation set; and according to the mass ratio of the machine-made sand to the deionized water, calculating to obtain the concentration phi 0 of the polyaluminum chloride attached to the machine-made sand. The limitation problem that the existing machine-made sand detection field is lack of the unknown content of the active ingredients of the polyaluminum chloride is effectively solved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of civil engineering materials, and more specifically to a method for detecting the concentration of residual polyaluminium chloride and the content of effective components in machine-made sand. Background Art

[0002] Natural river sand or artificial sand is one of the important raw materials for concrete. In recent years, river sand resources have decreased, and artificial sand has been widely used in the fields of bridge and road engineering due to its regular shape and excellent mechanical properties. However, a large amount of stone powder and mud powder will be produced during the production of artificial sand, which is difficult to remove with a simple screening process and requires ore washing operations. In order to control costs, artificial sand manufacturers usually pursue non-standardization and high efficiency in the ore washing process. Polyaluminum chloride is often used as a flocculant to accelerate the sedimentation of mud powder and stone powder, which will cause the artificial sand to be attached with polyaluminum chloride with an unknown effective ingredient content, which actually changes the performance of the artificial sand, and then has a greater impact on the performance of concrete, resulting in a deterioration in the quality of concrete engineering.

[0003] The study clearly stated that when polyaluminium chloride is attached to machine-made sand, it will significantly affect the slump and slump loss of concrete. Specifically, for polyaluminium chloride with an effective ingredient content of 26%, for every 0.01% increase in the amount of polyaluminium chloride attached to the machine-made sand, the mortar expansion will be reduced by about 10mm. When the polyaluminium chloride attached to the machine-made sand reaches 0.03% of the mass of the machine-made sand, the mortar expansion can be reduced by more than 25%. At the same time, polyaluminium chloride has the characteristics of different effective ingredient contents. The flocculation effect of polyaluminium chloride with a larger effective ingredient content is better. Therefore, when using polyaluminium chloride with an effective ingredient content of 30% for testing, the above two thresholds can be reduced to 0.005% and 0.015% respectively.

[0004] The existing tests for polyaluminium chloride cannot detect polyaluminium chloride with unknown effective ingredient content attached to machine-made sand. At the same time, there are other interfering impurities attached to machine-made sand, such as fine mud powder particles and pigment particles that cause sand washing water to appear yellow-brown. In fact, the engineering industry has very strict regulations on the fluidity of concrete under certain mix conditions, which determines whether the fresh concrete can be pumped and poured smoothly. At this time, the significance of only testing polyaluminium chloride with a certain effective ingredient content is very limited. What is more needed is a method that can simultaneously realize the detection of the concentration of polyaluminium chloride attached to machine-made sand and the content of effective ingredients, so as to more comprehensively determine the performance of machine-made sand and ensure that the fluidity of concrete meets on-site requirements.

[0005] Therefore, a rapid, low-cost, and accurate method for detecting different concentrations and effective ingredient contents of polyaluminium chloride in machine-made sand is needed. Summary of the invention

[0006] 1. Technical issues to be resolved

[0007] In view of this, the present disclosure provides a method for detecting the concentration of residual polyaluminium chloride and the content of effective ingredients in machine-made sand, so as to solve the limitation problem of the lack of the unknown content of effective ingredients of polyaluminium chloride in the current machine-made sand detection field.

[0008] (II) Technical solution

[0009] The present disclosure provides a method for detecting the concentration of residual polyaluminium chloride and the content of effective components in machine-made sand, the method comprising:

[0010] S1: Prepare samples to be tested, standard samples and test reagents;

[0011] S2: Connect detection components and configure detection equipment;

[0012] S3: Testing the standard sample to obtain the SV relationship curve between the conductivity S output by the conductivity meter of the standard sample and the volume V of the added polyaluminium chloride standard aqueous solution;

[0013] S4: establishing a double threshold database of polyaluminium chloride standard aqueous solution under different concentrations and different active ingredient contents based on the SV relationship curve of the standard sample, and fitting the double threshold database of polyaluminium chloride standard aqueous solution into a nonlinear surface formula;

[0014] S5: Testing the sample to be tested, and obtaining an SV relationship curve between the conductivity S output by the conductivity meter of the sample to be tested and the volume V of the sample to be tested;

[0015] S6: Obtain characteristic points V1 and V2 from the SV relationship curve of the sample to be tested, substitute V1 and V2 into the nonlinear surface formula fitted by the database of double threshold values ​​of polyaluminium chloride standard aqueous solution, and obtain the concentration Φ and the effective component content Al of the polyaluminium chloride in the sample to be tested by solving the nonlinear equation group;

[0016] S7: According to the mass ratio of machine-made sand to deionized water, the concentration of polyaluminium chloride Φ0 attached to the machine-made sand is calculated.

[0017] In the above scheme, step S1 includes:

[0018] S11: fully mix the machine-made sand sample to be tested and deionized water in a mass ratio of 1:1 to 1:3 to obtain a sample to be tested;

[0019] S12: preparing polyaluminium chloride solid samples with different active ingredient contents, the active ingredient contents are 26% to 30% respectively, and the effective ingredient content step is 2%; using deionized water to prepare polyaluminium chloride standard aqueous solutions with concentrations of 0.004% to 0.016% as standard samples;

[0020] S13: Prepare Class A and Class B reagents as detection reagents, wherein the Class A reagent can react with polyaluminium chloride and has a relatively obvious reaction phenomenon, and the Class B reagent does not react with polyaluminium chloride but has good conductivity.

[0021] In the above scheme, the Class A reagent described in step S13 includes: copper sulfate, copper chloride, ferric chloride, potassium chloride, ferrous chloride, nickel chloride, potassium chromate, potassium dichromate or potassium permanganate; the concentration of the Class A reagent is 0.002mol / L~0.005mol / L; the Class B reagent described in step S13 includes: sodium sulfate, potassium sulfate, magnesium sulfate, ferrous sulfate or ferrous sulfate; the concentration of the Class B reagent is 0.001mol / L~0.003mol / L.

[0022] In the above scheme, step S2 includes:

[0023] S21: Connect the solution pools numbered 1 and 2 in series with copper wires, connect the positive electrode of the solution pool No. 1 to the negative electrode of the solution pool No. 4, and then connect them to the positive and negative electrodes of the conductivity meter; use a hose to connect the solution pools No. 1 and 2 to the solution pool No. 3, set up a peristaltic pump in the middle, and adjust the peristaltic pump flow rate to 2-5 ml / min;

[0024] S22: Prepare a 4-channel synchronous electromagnetic stirrer with a rotation speed of 100 r / min to 500 r / min.

[0025] In the above scheme, step S3 includes:

[0026] S31: Take 200mL to 300mL of Class A reagent and inject it into the No. 1 solution tank of the detection equipment, and take another portion of the same volume of Class B reagent and inject it into the No. 2 solution tank of the detection equipment; take 500mL to 1000mL of the standard sample and add it into the No. 3 solution tank;

[0027] S32: Turn on the power supply, and the single-chip microcomputer immediately records the initial conductivity output conductivity S0; turn on the peristaltic pump, and add the polyaluminium chloride standard aqueous solution in the No. 3 solution pool to the No. 1 and No. 2 solution pools. After each 5ml to 10ml is added, the conductivity meter output conductivity S is recorded. x ; The conductivity S0 and S x Normalize it:

[0028] S=S x -S0

[0029] The SV relationship curve between the conductivity S output by the conductivity meter and the volume V of the added polyaluminium chloride standard aqueous solution was drawn using a single chip microcomputer, with the starting point being point 0.

[0030] In the above scheme, step S4 includes:

[0031] S41: for each polyaluminium chloride standard aqueous solution with different concentrations of active ingredient content, obtain the range of characteristic points on the curve under conditions of different concentrations and different active ingredient contents, record it as a double threshold represented by the volume V of the polyaluminium chloride standard aqueous solution added, and establish a database of double thresholds of polyaluminium chloride standard aqueous solutions under conditions of different concentrations and different active ingredient contents;

[0032] S42: Fitting the double threshold database of the polyaluminium chloride standard aqueous solution into a nonlinear surface formula.

[0033] In the above scheme, in the double threshold represented by the volume V of the added polyaluminium chloride standard aqueous solution in step S41, the maximum value of the conductivity S on the curve corresponding to threshold 1 is the corresponding volume V1 of the polyaluminium chloride standard aqueous solution, and the volume V2 of the polyaluminium chloride standard aqueous solution corresponding to the intersection of the curve and the x-axis of threshold 2;

[0034] The nonlinear surface formula for fitting the database of the double threshold value of the polyaluminium chloride standard aqueous solution described in step S42 is as follows:

[0035] V1=A1×Φ+B1×Mr+C1×Φ 2 +D1×Mr 2 +E1×Φ×Mr+F1

[0036] V2=A2×Φ+B2×Mr+C2×Φ 2 +D2×Mr 2 +E2×Φ×Mr+F2

[0037] Among them, the abscissa x and the ordinate y correspond to the concentration Φ and the effective ingredient content Al of the polyaluminium chloride standard sample respectively. Except for V1, V2, Φ and Al, other parameters are constant coefficients.

[0038] In the above scheme, step S5 includes:

[0039] S51: Take 200mL to 300mL of Class A reagent and inject it into the No. 1 solution tank of the detection equipment, take an equal volume of Class B reagent and inject it into the No. 2 solution tank of the detection equipment; take 500mL to 1000mL of the sample to be tested and add it into the No. 3 solution tank;

[0040] S52: Turn on the power supply, and the single-chip microcomputer immediately records the initial output conductivity S0 of the conductivity meter; turn on the peristaltic pump, and add the sample to be tested in the No. 3 solution pool to the No. 1 and No. 2 solution pools. After each 5ml to 10ml of filling, record the output conductivity S of the conductivity meter. x ; The conductivity S0 and S x Normalize it:

[0041] S=S x -S0

[0042] The SV relationship curve between the conductivity S output by the conductivity meter and the volume V of the sample to be tested is drawn using a single-chip microcomputer, with the starting point being point 0.

[0043] In the above scheme, the characteristic point V1 in step S6 is the volume V1 of the sample to be detected, corresponding to the maximum value of the conductivity S; the characteristic point V2 in step S6 is the volume V2 of the sample to be detected, corresponding to the intersection of the curve and the x-axis.

[0044] In the above scheme, the concentration Φ0 of polyaluminium chloride attached to the machine-made sand is calculated in step S7 by the following calculation method:

[0045] Φ0=Φ×m2 / m1

[0046] Wherein, m1 is the mass of machine-made sand in step S1, and m2 is the mass of deionized water in step S1.

[0047] In the above scheme, the method further includes: judging whether the machine-made sand raw material from which the machine-made sand sample is obtained can be used for concrete preparation according to the calculated concentration Φ0 of polyaluminium chloride attached to the machine-made sand and the effective component content Al of polyaluminium chloride, wherein:

[0048] When the test result shows that the effective component content of polyaluminium chloride is 26%, when the concentration of polyaluminium chloride Φ0≤0.01%, it has little effect on the slump and slump loss of concrete, and can be used to prepare concrete; when the concentration of polyaluminium chloride is 0.01%<Φ0≤0.03%, it has a significant effect on the slump and slump loss of concrete, and the concrete mix ratio needs to be adjusted, and the amount of water reducer needs to be appropriately increased to meet the slump requirements; when the concentration of polyaluminium chloride Φ0>0.03%, its effect on the slump and slump loss of concrete can no longer be compensated by water reducer, and the machine-made sand needs to be cleaned twice with clean water before re-testing;

[0049] When the test result is 30% active ingredient content of polyaluminium chloride, when the concentration of polyaluminium chloride Φ0≤0.005%, its effect on the slump and slump loss of concrete is small, and it can be used to prepare concrete; when the concentration of polyaluminium chloride is 0.005%<Φ0≤0.015%, its effect on the slump and slump loss of concrete is significant, and the concrete mix ratio needs to be adjusted, and the amount of water reducer needs to be appropriately increased to meet the slump requirements; when the concentration of polyaluminium chloride Φ0>0.015%, its effect on the slump and slump loss of concrete can no longer be compensated by water reducer, and the machine-made sand needs to be cleaned twice with clean water and re-tested.

[0050] (III) Beneficial effects

[0051] It can be seen from the above technical solution that the method for detecting the concentration of residual polyaluminium chloride and the content of effective ingredients in the machine-made sand provided by the present disclosure has at least the following beneficial effects:

[0052] 1. The method for detecting the concentration of residual polyaluminium chloride and the content of effective ingredients in the machine-made sand provided by the present invention directly, quickly and accurately tests the effective ingredient content of the polyaluminium chloride flocculant attached to the machine-made sand and the corresponding concentration value through a one-time detection method, which effectively solves the limitation problem of the lack of unknown effective ingredient content of polyaluminium chloride in the current machine-made sand detection field, and ensures the reasonable evaluation of the quality of the machine-made sand. This has not been mentioned in the prior art, which is also the biggest difference and the most important innovation point between the present invention and the prior art. This is because the prior art has many concentration test or characterization methods of a certain polyaluminium chloride flocculant (existing turbidity method, absorbance method, etc.), which is not conducive to detecting its concentration under the condition of the presence of flocculants with multiple effective ingredient contents, which will result in a larger actual measured concentration of a flocculant with a lower effective ingredient content or a smaller actual measured concentration of a flocculant with a higher effective ingredient content, which is not conducive to the reasonable evaluation of the quality of the machine-made sand.

[0053] 2. The method for detecting the concentration of residual polyaluminium chloride and the content of effective ingredients in machine-made sand provided by the present invention fully considers the soluble impurities other than the polyaluminium chloride flocculant attached to the machine-made sand and the fine particles that change the color of the aqueous solution, and adopts the method of AC conductivity and compensation test to avoid the interference of the above impurities on the detection results. The detection of polyaluminium chloride aqueous solution is expanded to the detection of the concentration of flocculant attached to the machine-made sand, which is completely different from the prior art. At the same time, it also solves the problems that have not been solved by the prior art (existing turbidity method, absorbance method, etc.), highlighting the innovativeness of the present invention.

[0054] 3. The method for detecting the concentration of residual polyaluminium chloride and the content of effective ingredients in machine-made sand provided by the present invention realizes the judgment of the content and concentration of effective ingredients of polyaluminium chloride by establishing a double threshold value of the conductivity S-dropping volume V curve of the standard aqueous solution of polyaluminium chloride and a double threshold value database. Compared with the prior art which only uses a single slope and a single inflection point, it is more accurate and can realize the accurate judgment of polyaluminium chloride attached to machine-made sand with different effective ingredient contents at the same concentration. The operation method is simple and has strong universality, and can simply and effectively judge the quality of machine-made sand.

[0055] 4. The present invention provides a method for detecting the concentration of residual polyaluminium chloride and the content of effective ingredients in machine-made sand, and establishes a complete set of evaluation methods and post-treatment methods for polyaluminium chloride flocculants attached to machine-made sand that affect the workability of concrete. This can prompt on-site staff to pay attention to questionable machine-made sand raw materials in a timely manner to the greatest extent possible, and assist technical personnel in making adjustments to the concrete mix ratio to ensure the quality of concrete projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The above contents and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0057] Figure 1 It is a flow chart of a method for detecting the concentration of residual polyaluminium chloride and the content of effective components in machine-made sand according to an embodiment of the present disclosure.

[0058] Figure 2a and Figure 2b It is a dual threshold database of a polyaluminium chloride standard aqueous solution with a concentration of 0.004% to 0.016% and an active ingredient content of 26% to 30% according to an embodiment of the present disclosure; wherein the abscissa x and the ordinate y correspond to the concentration Φ and the active ingredient content Al of the polyaluminium chloride standard sample, respectively. Figure 2a The z axis in the middle is the volume V1 of the sample to be tested. Figure 2b The middle z-axis is the volume V2 of the sample to be tested;

[0059] Figure 3 is the SV curve obtained by testing sample 1 according to an embodiment of the present disclosure;

[0060] Figure 4 is the SV curve obtained by testing sample 2 according to an embodiment of the present disclosure;

[0061] Figure 5 SV curve obtained by testing sample 3 according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0062] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0063] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0064] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0065] In order to solve the problem that the residual amount of machine-made sand containing different effective ingredient contents and unknown concentration of polyaluminium chloride is difficult to quantitatively detect, and at the same time avoid the influence of soluble impurities attached to the machine-made sand and colored particles that change the water quality on the test results, the present disclosure proposes a detection method for the concentration and effective ingredient content of residual polyaluminium chloride in machine-made sand, which directly, quickly and accurately tests the effective ingredient content and corresponding concentration value of polyaluminium chloride attached to the machine-made sand, ensuring a reasonable evaluation of the quality of the machine-made sand, which has not been mentioned in the prior art, highlighting the innovation of the present disclosure; at the same time, the present disclosure fully considers the soluble impurities other than the polyaluminium chloride flocculant attached to the machine-made sand and the fine particles that change the color of the aqueous solution, avoiding the interference of the above impurities on the test results, which is completely different from the prior art; in addition, the present disclosure establishes a double threshold value of the SV curve (i.e., the conductivity S-drop volume V curve) of the polyaluminium chloride standard aqueous solution and a double threshold database to realize the judgment of the effective ingredient content and concentration, and also provides an evaluation method and a post-processing method for polyaluminium chloride attached to machine-made sand to ensure the quality of concrete engineering.

[0066] like Figure 1 As shown, Figure 1 A flow chart of a method for detecting the concentration of residual polyaluminium chloride and the content of effective components in machine-made sand according to an embodiment of the present disclosure is shown, and the method comprises the following steps:

[0067] S1: Prepare samples to be tested, standard samples and test reagents; specifically include:

[0068] S11: Fully mix the machine-made sand sample to be tested and deionized water in a mass ratio of 1:1 to 1:3 to ensure that the polyaluminium chloride flocculant molecules attached to the machine-made sand sample can be fully dissolved in water, thereby obtaining a polyaluminium chloride flocculant aqueous solution containing an unknown effective component as the sample to be tested;

[0069] S12: Prepare polyaluminium chloride solid samples with different active ingredient contents, the active ingredient contents are 26% to 30% and the effective ingredient content step is 2%. Use deionized water to prepare polyaluminium chloride standard aqueous solutions with concentrations of 0.004% to 0.016% as standard samples;

[0070] S13: preparing type A and type B reagents as detection reagents, wherein the type A reagent can react with the polyaluminium chloride flocculant and has a relatively obvious reaction phenomenon, and the type B reagent does not react with the polyaluminium chloride flocculant but has good conductivity;

[0071] In this step, the Class A reagent includes: copper sulfate, copper chloride, ferric chloride, potassium chloride, ferrous chloride, nickel chloride, potassium chromate, potassium dichromate or potassium permanganate, etc. The Class A reagent can react with the polyaluminium chloride flocculant and has a relatively obvious reaction phenomenon; the concentration of the Class A reagent is 0.002mol / L to 0.005mol / L. Under this concentration condition, when the concentration of the polyaluminium chloride flocculant in the sample to be detected is extremely low, it is conducive to the rapid reaction of the two.

[0072] In this step, the Class B reagent includes: sodium sulfate, potassium sulfate, magnesium sulfate, ferric sulfate or ferrous sulfate, etc. This type of reagent does not react with the polyaluminum chloride flocculant, but has good conductivity; the concentration of the Class B reagent is 0.001 mol / L to 0.003 mol / L. Under this concentration condition, when the concentration of the polyaluminum chloride flocculant in the sample to be tested is extremely low, it can ensure that the polyaluminum chloride flocculant component has good conductivity.

[0073] S2: Connect the detection components and configure the detection equipment; specifically include:

[0074] S21: Connect the solution pools numbered 1 and 2 in series with copper wires, connect the positive electrode of the solution pool No. 1 to the negative electrode of the solution pool No. 4, and then connect them to the positive and negative electrodes of the conductivity meter; use a hose to connect the solution pools No. 1 and 2 to the solution pool No. 3, set up a peristaltic pump in the middle, and adjust the flow rate of the peristaltic pump to 2-5 ml / min. This speed can ensure that the polyaluminium chloride flocculant reacts fully with the Class A reagent, and can also ensure a stable output of the conductivity meter;

[0075] S22: Prepare a 4-channel synchronous electromagnetic stirrer with a rotation speed of 100r / min~500r / min to accelerate the full reaction of polyaluminium chloride flocculant and Class A reagent, and also avoid the influence of irregular molecular thermal motion in the solution on conductivity, so as to ensure stable current output; the reason for using this circuit structure to carry out the test is that it can shield the interference of soluble impurities (including soluble salts, mud powder, stone powder, etc.) attached to the machine-made sand on the test results, thereby showing the difference from the existing technology.

[0076] S3: Testing the standard sample to obtain the SV relationship curve between the conductivity S output by the conductivity meter of the standard sample and the volume V of the added polyaluminium chloride standard aqueous solution; specifically including:

[0077] S31: Take 200mL to 300mL of Class A reagent and inject it into the No. 1 solution tank of the detection equipment, and take another portion of the same volume of Class B reagent and inject it into the No. 2 solution tank of the detection equipment; take 500mL to 1000mL of the standard sample and add it into the No. 3 solution tank;

[0078] S32: Turn on the power supply, and the single-chip microcomputer immediately records the initial conductivity output conductivity S0; turn on the peristaltic pump, and add the polyaluminium chloride standard aqueous solution in the No. 3 solution pool to the No. 1 and No. 2 solution pools. After each 5ml to 10ml is added, the conductivity meter output conductivity S is recorded. x ; The conductivity S0 and S x Normalize it:

[0079] S=S x -S0

[0080] The SV relationship curve between the conductivity S output by the conductivity meter and the volume V of the added polyaluminium chloride standard aqueous solution was drawn using a single chip microcomputer, with the starting point being point 0.

[0081] S4: Based on the SV relationship curve of the standard sample, a database of double threshold values ​​of polyaluminium chloride standard aqueous solution under different concentrations and different active ingredient contents is established, and the database of double threshold values ​​of polyaluminium chloride standard aqueous solution is fitted into a nonlinear surface formula; specifically including:

[0082] S41: for each polyaluminium chloride standard aqueous solution with different concentrations of active ingredient content, obtain the range of characteristic points on the curve under conditions of different concentrations and different active ingredient contents, record it as a double threshold represented by the volume V of the polyaluminium chloride standard aqueous solution added, and establish a database of double thresholds of polyaluminium chloride standard aqueous solutions under conditions of different concentrations and different active ingredient contents;

[0083] In this step, in the double threshold represented by the volume V of the added polyaluminium chloride standard aqueous solution, the maximum value of the conductivity S on the curve corresponding to threshold 1 is the corresponding volume V1 of the polyaluminium chloride standard aqueous solution, and the volume V2 of the polyaluminium chloride standard aqueous solution corresponding to the intersection of the curve and the x-axis of threshold 2;

[0084] S42: fitting the database of the double threshold value of the polyaluminium chloride standard aqueous solution into a nonlinear surface formula;

[0085] In this step, the database of the double threshold value of the polyaluminium chloride standard aqueous solution (such as Figure 2a , Figure 2b )The nonlinear surface formula for fitting is as follows:

[0086] V1=A1×Φ+B1×Mr+C1×Φ 2 +D1×Mr 2 +E1×Φ×Mr+F1

[0087] V2=A2×Φ+B2×Mr+C2×Φ 2 +D2×Mr 2 +E2×Φ×Mr+F2

[0088] Among them, the horizontal axis x and the vertical axis y correspond to the concentration Φ and the effective ingredient content Al of the polyaluminium chloride standard sample respectively. Figure 2a The z axis in the middle is the volume V1 of the sample to be tested. Figure 2b The z axis in the middle is the volume V2 of the sample to be tested. Except for V1, V2, Φ and Al, other parameters are constant coefficients. The constant coefficient fitting results and fitting goodness are shown in the following table:

[0089] <![CDATA[A1]]> <![CDATA[B1]]> <![CDATA[C1]]> <![CDATA[D1]]> <![CDATA[E1]]> <![CDATA[F1]]> <![CDATA[R 2 ]]> <![CDATA[2.79×10 5 ]]> <![CDATA[2.82×10 2 ]]> <![CDATA[-2.60×10 -5 ]]> <![CDATA[-3.39×10 2 ]]> <![CDATA[-1.25×10 6 ]]> 8.81 0.9996 <![CDATA[A2]]> <![CDATA[B2]]> <![CDATA[C2]]> <![CDATA[D2]]> <![CDATA[E2]]> <![CDATA[F2]]> <![CDATA[R 2 ]]> <![CDATA[1.12×10 5 ]]> <![CDATA[2.78×10 2 ]]> <![CDATA[3.16×10 -6 ]]> <![CDATA[-4.79×10 2 ]]> <![CDATA[-4.70×10 5 ]]> -14.07 0.9935

[0090] S5: Testing the sample to be tested to obtain the SV relationship curve between the conductivity S output by the conductivity meter of the sample to be tested and the volume V of the sample to be tested; specifically including:

[0091] S51: Take 200mL to 300mL of Class A reagent and inject it into the No. 1 solution tank of the detection equipment, take an equal volume of Class B reagent and inject it into the No. 2 solution tank of the detection equipment; take 500mL to 1000mL of the sample to be tested and add it into the No. 3 solution tank;

[0092] S52: Turn on the power supply, and the single-chip microcomputer immediately records the initial output conductivity S0 of the conductivity meter; turn on the peristaltic pump, and add the sample to be tested in the No. 3 solution pool to the No. 1 and No. 2 solution pools. After each 5ml to 10ml of filling, record the output conductivity S of the conductivity meter. x ; The conductivity S0 and S x Normalize it:

[0093] S=S x -S0

[0094] The SV relationship curve between the conductivity S output by the conductivity meter and the volume V of the sample to be tested is drawn using a single-chip microcomputer, with the starting point being point 0.

[0095] S6: Obtain characteristic points V1 and V2 from the SV relationship curve of the sample to be tested, substitute V1 and V2 into the nonlinear surface formula fitted by the database of double threshold values ​​of polyaluminium chloride standard aqueous solution, and obtain the concentration Φ and the effective component content Al of the polyaluminium chloride in the sample to be tested by solving the nonlinear equation group;

[0096] In this step, the characteristic point V1 is the volume V1 of the sample to be detected, corresponding to the maximum value of the conductivity S; the characteristic point V2 is the volume V2 of the sample to be detected, corresponding to the intersection of the curve and the x-axis.

[0097] S7: According to the mass ratio of machine-made sand to deionized water, the concentration of polyaluminium chloride attached to the machine-made sand is calculated as Φ0. The calculation method used is:

[0098] Φ0=Φ×m2 / m1

[0099] Wherein, m1 is the mass of machine-made sand in step S1, and m2 is the mass of deionized water in step S1.

[0100] Thus, the present invention provides a method for detecting the concentration of residual polyaluminium chloride and the content of effective components in machine-made sand, and obtains the concentration Φ0 of polyaluminium chloride attached to the machine-made sand and the content Al of effective components of polyaluminium chloride.

[0101] Furthermore, based on the concentration Φ0 of the polyaluminium chloride attached to the machine-made sand obtained in the present disclosure and the effective component content Al of the polyaluminium chloride, it can be further judged whether the machine-made sand raw material from which the machine-made sand sample is obtained can be used for concrete preparation, specifically including:

[0102] When the test result shows that the effective component content of polyaluminium chloride is 26%, when the concentration of polyaluminium chloride Φ0≤0.01%, it has little effect on the slump and slump loss of concrete, and can be used to prepare concrete; when the concentration of polyaluminium chloride is 0.01%<Φ0≤0.03%, it has a significant effect on the slump and slump loss of concrete, and the concrete mix ratio needs to be adjusted, and the amount of water reducer needs to be appropriately increased to meet the slump requirements; when the concentration of polyaluminium chloride Φ0>0.03%, its effect on the slump and slump loss of concrete can no longer be compensated by water reducer, and the machine-made sand needs to be cleaned twice with clean water before re-testing;

[0103] When the test result is 30% active ingredient content of polyaluminium chloride, when the concentration of polyaluminium chloride Φ0≤0.005%, its effect on the slump and slump loss of concrete is small, and it can be used to prepare concrete; when the concentration of polyaluminium chloride is 0.005%<Φ0≤0.015%, its effect on the slump and slump loss of concrete is significant, and the concrete mix ratio needs to be adjusted, and the amount of water reducer needs to be appropriately increased to meet the slump requirements; when the concentration of polyaluminium chloride Φ0>0.015%, its effect on the slump and slump loss of concrete can no longer be compensated by water reducer, and the machine-made sand needs to be cleaned twice with clean water and re-tested.

[0104] The following will further illustrate the method for detecting the effective component content of the flocculant in the machine-made sand provided by the present disclosure in combination with an embodiment, wherein the flocculant is polyaluminium chloride. This embodiment takes machine-made sand with polyaluminium chloride attached as the research object, and obtains a dual threshold database of polyaluminium chloride standard aqueous solutions of different concentrations and different effective component contents according to the description in the specific implementation plan; it is fully mixed at a mass ratio of 1:1 to obtain a polyaluminium chloride aqueous solution with an unknown effective component content as a sample to be tested. Further testing obtains the conductivity and the corresponding volume of the solution added, as shown in Table 1.

[0105]

[0106] Table 1 Test results of conductivity and volume of solution sample to be tested

[0107] The SV curve drawn according to Table 1 is as follows Figure 3 , Figure 4 , Figure 5 shown.

[0108] Figure 3 The middle dual thresholds have V1=25.47, V2=57.59; Figure 4 The middle dual thresholds have V1=24.56, V2=53.95; Figure 5 The dual threshold values ​​of V1=25.11 and V2=59.30.

[0109] Substituting the above threshold into the nonlinear surface formula fitted by the database of double threshold values ​​of polyaluminium chloride standard aqueous solution shown in FIG2 , it can be learned that sample 1 contains polyaluminium chloride with a concentration of 0.004% and an active ingredient content of 26%, sample 2 contains polyaluminium chloride with a concentration of 0.012% and an active ingredient content of 26%, and sample 3 contains polyaluminium chloride with a concentration of 0.004% and an active ingredient content of 30%.

[0110] At the same time, since the mass ratio of machine-made sand to water is 1:1 when preparing the samples to be tested, the following residues remain in the three machine-made sand samples:

[0111] Sample 1: Polyaluminium chloride with a concentration of 0.004% and an active ingredient content of 26% has little effect on the slump and slump loss of concrete and can be used to prepare concrete;

[0112] Sample 2: Polyaluminium chloride with a concentration of 0.012% and an active ingredient content of 26% has a significant effect on the slump and slump loss of concrete. It is necessary to adjust the concrete mix ratio and appropriately increase the amount of water reducing agent to meet the slump requirements;

[0113] Sample 3: Polyaluminium chloride with a concentration of 0.004% and an active ingredient content of 30% has little effect on the slump and slump loss of concrete and can be used to prepare concrete.

[0114] So far, the embodiments of the present disclosure have been described in detail in conjunction with the accompanying drawings. It should be noted that the implementation methods not shown or described in the drawings or the body of the specification are all forms known to ordinary technicians in the relevant technical field and are not described in detail. In addition, the above definitions of each element and method are not limited to the various specific structures, shapes or methods mentioned in the embodiments, and ordinary technicians in the field can simply change or replace them.

[0115] It will be appreciated by those skilled in the art that the features described in the various embodiments of the present disclosure may be combined and / or combined in a variety of ways, even if such combinations or combinations are not explicitly described in the present disclosure. In particular, without departing from the spirit and teachings of the present disclosure, the features described in the various embodiments of the present disclosure may be combined and / or combined in a variety of ways. All of these combinations and / or combinations fall within the scope of the present disclosure.

[0116] The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A method for detecting the concentration of residual polyaluminium chloride and the content of effective ingredients in machine-made sand, characterized in that: The method includes: S1: Prepare samples to be tested, standard samples and test reagents; S2: Connect detection components and configure detection equipment; S3: Testing the standard sample to obtain the SV relationship curve between the conductivity S output by the conductivity meter of the standard sample and the volume V of the added polyaluminium chloride standard aqueous solution; S4: establishing a double threshold database of polyaluminium chloride standard aqueous solution under different concentrations and different active ingredient contents based on the SV relationship curve of the standard sample, and fitting the double threshold database of polyaluminium chloride standard aqueous solution into a nonlinear surface formula; S5: testing the sample to be tested, and obtaining a SV relationship curve between the conductivity S output by the conductivity meter of the sample to be tested and the volume V of the sample to be tested; S6: Obtain characteristic points V1 and V2 from the SV relationship curve of the sample to be tested, substitute V1 and V2 into the nonlinear surface formula fitted by the database of double threshold values ​​of polyaluminium chloride standard aqueous solution, and obtain the concentration Φ and the effective component content Al of the polyaluminium chloride in the sample to be tested by solving the nonlinear equation group; S7: According to the mass ratio of machine-made sand to deionized water, the concentration of polyaluminium chloride Φ0 attached to the machine-made sand is calculated.

2. The method for detecting the concentration of residual polyaluminium chloride and the content of effective components in machine-made sand according to claim 1, characterized in that: Step S1 includes: S11: fully mix the machine-made sand sample to be tested and deionized water in a mass ratio of 1:1 to 1:3 to obtain a sample to be tested; S12: preparing polyaluminium chloride solid samples with different active ingredient contents, the active ingredient contents are 26% to 30% respectively, and the effective ingredient content step is 2%; using deionized water to prepare polyaluminium chloride standard aqueous solutions with concentrations of 0.004% to 0.016% as standard samples; S13: Prepare Class A and Class B reagents as detection reagents, wherein the Class A reagent can react with polyaluminium chloride and has a relatively obvious reaction phenomenon, and the Class B reagent does not react with polyaluminium chloride but has good conductivity.

3. The method for detecting the concentration of residual polyaluminium chloride and the content of effective components in machine-made sand according to claim 2, characterized in that: The Class A reagent in step S13 includes: copper sulfate, copper chloride, ferric chloride, potassium chloride, ferrous chloride, nickel chloride, potassium chromate, potassium dichromate or potassium permanganate; the concentration of the Class A reagent is 0.002 mol / L to 0.005 mol / L; The type B reagent in step S13 includes: sodium sulfate, potassium sulfate, magnesium sulfate, ferrous sulfate or ferrous sulfate; the concentration of the type B reagent is 0.001 mol / L to 0.003 mol / L.

4. The method for detecting the concentration of residual polyaluminium chloride and the content of effective components in machine-made sand according to claim 1, characterized in that: Step S2 includes: S21: Connect the solution pools numbered 1 and 2 in series with copper wires, connect the positive electrode of the solution pool No. 1 to the negative electrode of the solution pool No. 4, and then connect them to the positive and negative electrodes of the conductivity meter; use a hose to connect the solution pools No. 1 and 2 to the solution pool No. 3, set up a peristaltic pump in the middle, and adjust the peristaltic pump flow rate to 2-5 ml / min; S22: Prepare a 4-channel synchronous electromagnetic stirrer with a rotation speed of 100 r / min to 500 r / min.

5. The method for detecting the concentration of residual polyaluminium chloride and the content of effective components in machine-made sand according to claim 1, characterized in that: Step S3 includes: S31: Take 200mL to 300mL of Class A reagent and inject it into the No. 1 solution tank of the detection equipment, and take another portion of the same volume of Class B reagent and inject it into the No. 2 solution tank of the detection equipment; take 500mL to 1000mL of the standard sample and add it into the No. 3 solution tank; S32: Turn on the power supply, and the single-chip microcomputer immediately records the initial conductivity output conductivity S0; turn on the peristaltic pump, and add the polyaluminium chloride standard aqueous solution in the No. 3 solution pool to the No. 1 and No. 2 solution pools. After each 5ml to 10ml is added, the conductivity meter output conductivity S is recorded. x ; The conductivity S0 and S x Normalize it: S=S x -S0 The SV relationship curve between the conductivity S output by the conductivity meter and the volume V of the added polyaluminium chloride standard aqueous solution was drawn using a single chip microcomputer, with the starting point being 0.

6. The method for detecting the concentration of residual polyaluminium chloride and the content of effective components in machine-made sand according to claim 1, characterized in that: Step S4 includes: S41: for each polyaluminium chloride standard aqueous solution with different concentrations of active ingredient content, obtain the range of characteristic points on the curve under conditions of different concentrations and different active ingredient contents, record it as a double threshold represented by the volume V of the polyaluminium chloride standard aqueous solution added, and establish a database of double thresholds of polyaluminium chloride standard aqueous solutions under conditions of different concentrations and different active ingredient contents; S42: Fitting the double threshold database of the polyaluminium chloride standard aqueous solution into a nonlinear surface formula.

7. The method for detecting the concentration of residual polyaluminium chloride and the content of effective components in machine-made sand according to claim 6, characterized in that: In the double threshold represented by the volume V of the added polyaluminium chloride standard aqueous solution in step S41, the maximum value of the conductivity S on the curve corresponding to threshold 1 is the corresponding volume V1 of the polyaluminium chloride standard aqueous solution, and the volume V2 of the polyaluminium chloride standard aqueous solution corresponding to the intersection of the curve and the x-axis of threshold 2; The nonlinear surface formula for fitting the database of the double threshold value of the polyaluminium chloride standard aqueous solution described in step S42 is as follows: V1=A1×Φ+B1×Mr+C1×Φ 2 +D1×Mr 2 +E1×Φ×Mr+F1 <h2 style=";text-align:left;direction:ltr">V2 = A2×Φ + B2×Mr + C2×Φ<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> +D2×Mr<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> +E2×Φ×Mr+F2 Among them, the abscissa x and the ordinate y correspond to the concentration Φ and the effective ingredient content Al of the polyaluminium chloride standard sample respectively. Except for V1, V2, Φ and Al, other parameters are constant coefficients.

8. The method for detecting the concentration of residual polyaluminium chloride and the content of effective components in machine-made sand according to claim 1, characterized in that: Step S5 includes: S51: Take 200mL to 300mL of Class A reagent and inject it into the No. 1 solution tank of the detection equipment, take an equal volume of Class B reagent and inject it into the No. 2 solution tank of the detection equipment; take 500mL to 1000mL of the sample to be tested and add it into the No. 3 solution tank; S52: Turn on the power supply, and the single-chip microcomputer immediately records the initial output conductivity S0 of the conductivity meter; turn on the peristaltic pump, and add the sample to be tested in the No. 3 solution pool to the No. 1 and No. 2 solution pools. After each 5ml to 10ml of filling, record the output conductivity S of the conductivity meter. x ; The conductivity S0 and S x Normalize it: S=S x -S0 The SV relationship curve between the conductivity S output by the conductivity meter and the volume V of the sample to be tested is drawn using a single-chip microcomputer, with the starting point being point 0.

9. The method for detecting the concentration of residual polyaluminium chloride and the content of effective components in machine-made sand according to claim 1, characterized in that: The characteristic point V1 in step S6 is the volume V1 of the sample to be detected, corresponding to the maximum value of the conductivity S; The characteristic point V2 in step S6 is the volume V2 of the sample to be detected, corresponding to the intersection of the curve and the x-axis.

10. The method for detecting the concentration of residual polyaluminium chloride and the content of effective components in machine-made sand according to claim 1, characterized in that: The calculation method used in step S7 to obtain the concentration Φ0 of polyaluminium chloride attached to the machine-made sand is: Φ0=Φ×m2 / m1 Wherein, m1 is the mass of machine-made sand in step S1, and m2 is the mass of deionized water in step S1.

11. The method for detecting the concentration of residual polyaluminium chloride and the content of effective components in machine-made sand according to claim 1, characterized in that: The method further includes: According to the calculated concentration Φ0 of polyaluminium chloride attached to the machine-made sand and the content Al of the effective component of polyaluminium chloride, it is judged whether the machine-made sand raw material from which the machine-made sand sample is obtained can be used for concrete preparation, wherein: When the test result shows that the effective component content of polyaluminium chloride is 26%, when the concentration of polyaluminium chloride Φ0≤0.01%, it has little effect on the slump and slump loss of concrete, and can be used to prepare concrete; when the concentration of polyaluminium chloride is 0.01%<Φ0≤0.03%, it has a significant effect on the slump and slump loss of concrete, and the concrete mix ratio needs to be adjusted, and the amount of water reducer needs to be appropriately increased to meet the slump requirements; when the concentration of polyaluminium chloride Φ0>0.03%, its effect on the slump and slump loss of concrete can no longer be compensated by water reducer, and the machine-made sand needs to be cleaned twice with clean water before re-testing; When the test result is 30% active ingredient content of polyaluminium chloride, when the concentration of polyaluminium chloride Φ0≤0.005%, its effect on the slump and slump loss of concrete is small, and it can be used to prepare concrete; when the concentration of polyaluminium chloride is 0.005%<Φ0≤0.015%, its effect on the slump and slump loss of concrete is significant, and the concrete mix ratio needs to be adjusted, and the amount of water reducer needs to be appropriately increased to meet the slump requirements; when the concentration of polyaluminium chloride Φ0>0.015%, its effect on the slump and slump loss of concrete can no longer be compensated by water reducer, and the machine-made sand needs to be cleaned twice with clean water and re-tested.

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