Rapid detection method and application of residual flocculant concentration in machine-made sand

Abstract

The present disclosure provides a rapid detection method and use of the residual concentration of flocculant in machine-made sand, the method comprising: S1, preparing different types of indicator standard solutions and different types of flocculant standard solutions of the first concentration and the second concentration respectively; S2, establishing a detection circuit; S3, using the indicator standard solution, the flocculant standard solution and the detection circuit to obtain different types of flocculant concentration-inflection point standard curves; S4, fully mixing and pre-treating the machine-made sand to be tested with distilled water to obtain a sample solution to be tested; S5, using the indicator standard solution, the sample solution to be tested and the detection circuit to obtain the inflection point on the current value-flocculant volume relationship curve; according to the inflection point and the standard curve, the residual concentration of different types of flocculants in the machine-made sand is obtained. The method disclosed in the present disclosure quickly determines the quality of machine-made sand at the construction site, and provides an applicable solution to improve the quality of concrete engineering.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and in particular to a method for quickly detecting the residual concentration of flocculant in machine-made sand and its application. Background Art

[0002] The fine aggregate used in the preparation of concrete is generally natural river sand. However, due to the non-renewable nature of natural river sand, the country has strictly restricted the excavation of natural river sand in recent years, causing the concrete industry to begin to use machine-made sand instead of natural river sand. Machine-made sand is usually obtained by crushing, screening and shaping rocks, and is a kind of artificially produced fine aggregate. When producing machine-made sand, the original stone and the crushed particles need to be cleaned to remove fine sediment, stone powder and clay particles produced by crushing. The national standard GB 51186 "Design Specifications for Machine-made Sand and Gravel Aggregate Plants" clearly states that the production process design of ore washing operations or wet sand making operations should use return water; when the original ore contains a high amount of mud (soil), a mud (soil) removal process should be adopted. At this time, in order to reduce costs and improve water circulation efficiency, the sand and gravel plant may discharge sewage containing mud and sand into the sedimentation tank, use flocculants to quickly flocculate and precipitate mud and sand and other substances, and then extract the supernatant to wash the machine-made sand. Because the machine-made sand plant adds flocculants more arbitrarily during the production process, different levels of flocculants remain in the machine-made sand.

[0003] Through a large number of experiments, it is concluded that when the residual amount of polyacrylamide flocculants in machine-made sand reaches 0.003% of the mass of sand (based on the amount of water used for mixing, the concentration of aqueous solution is 0.018%), the fluidity of mortar will be significantly reduced; when the residual amount of polyacrylamide flocculants in machine-made sand reaches 0.009% of the mass of sand (based on the amount of water used for mixing, the concentration of aqueous solution is 0.054%), the optimal dosage of polycarboxylic acid water reducer will be ineffective; when the residual amount of polyacrylamide flocculants in machine-made sand further increases, the fluidity of mortar will further deteriorate, which will seriously affect the pumpability of concrete.

[0004] Therefore, it is necessary to strictly control the concentration of residual flocculants in machine-made sand, which is the key to ensuring the quality of machine-made sand concrete. To control the concentration of residual flocculants in machine-made sand, it is necessary to establish a reasonable detection method. At present, there are two major types of flocculants commonly used in the market, namely polyacrylamide flocculants and inorganic polymer flocculants. Among them, polyacrylamide flocculants can be subdivided into anionic polyacrylamide, cationic polyacrylamide and non-ionic polyacrylamide according to the ionic form; inorganic polymer flocculants can be divided into polyaluminum chloride, polyferric sulfate, etc. according to inorganic substances. After consulting the literature and conducting research, it was found that the types of flocculants that may be used in the production process of machine-made sand are not transparent, but the commonly used types include 18 million molecular weight anionic polyacrylamide, 26% polyaluminum chloride or polyferric sulfate, etc., which makes it very difficult to detect the residual concentration of machine-made sand flocculants on site.

[0005] The content and type of flocculants attached to machine-made sand are unknown. Developing a detection method for only a single flocculant will ignore the impact of other types of flocculants, greatly limiting the application of detection technology in actual engineering detection. In addition, when developing a residual flocculant concentration detection technology in machine-made sand for construction sites, because on-site technicians have high requirements for detection efficiency and control of detection costs, and at the same time, they must take into account the simultaneous detection of multiple types of flocculants. If this can be achieved, it will be able to better evaluate the quality of machine-made sand, especially the residual concentration of flocculants and their impact on concrete performance. It can not only prompt on-site technicians to adjust the concrete mix ratio in a timely manner, but also ensure the quality of concrete projects.

[0006] Therefore, a low-cost, high-precision, high-efficiency and universal method for detecting the residual concentration of flocculants in machine-made sand is needed to quickly determine the quality of machine-made sand at the construction site and provide applicable solutions to improve the quality of concrete projects. Summary of the invention

[0007] In view of this, the first aspect of the present disclosure provides a rapid detection method for the residual concentration of flocculant in machine-made sand, comprising: S1, preparing different types of indicator standard solutions and different types of flocculant standard solutions of first concentration and second concentration respectively; S2, establishing a detection circuit; the detection circuit comprises a first solution pool, a third solution pool, a fourth solution pool, and a second solution pool connected in series in sequence, wherein a power supply is electrically connected to the first solution pool and the second solution pool respectively, and an ammeter is electrically connected to the first solution pool and the fourth solution pool respectively; and a fifth solution pool is connected to pipelines from the first solution pool to the fourth solution pool respectively; S3, using the indicator standard solution, the flocculant standard solution and the detection circuit to obtain different types of flocculant concentration-inflection point standard curves; wherein the inflection point is the inflection point on the current value-flocculant volume relationship curve; S4, fully mixing and pre-treating the machine-made sand to be tested with distilled water to obtain a sample solution to be tested; S5, using the indicator standard solution, the sample solution to be tested and the detection circuit to obtain the inflection point on the current value-flocculant volume relationship curve; according to the inflection point and the standard curve, the residual concentration of different types of flocculants in the machine-made sand is obtained.

[0008] According to an embodiment of the present disclosure, the first concentration in S1 is greater than the second concentration; the first concentration ranges from 1 g / L to 3 g / L; and the second concentration ranges from 0.01 g / L to 0.03 g / L.

[0009] According to an embodiment of the present disclosure, different types of indicator standard solutions in S1 include one or more of copper sulfate solution, copper chloride solution, silver nitrate solution, potassium thiocyanate solution, ferric hydroxide colloid, and starch solution; different types of flocculant standard solutions include one or more of anionic polyacrylamide, polyaluminum chloride, and polyferric sulfate.

[0010] According to an embodiment of the present disclosure, the fifth solution pool in S2 is connected to the first solution pool to the fourth solution pool through a hose and a peristaltic pump, respectively; the flow rate of the liquid added by the peristaltic pump is 50-100 ml / min.

[0011] According to an embodiment of the present disclosure, the detection circuit in S2 further includes a single chip microcomputer for analyzing the concentration of the flocculant.

[0012] According to an embodiment of the present disclosure, obtaining different types of flocculant concentration-inflection point standard curves in S3 includes: S31, adding an indicating standard solution with a first concentration of volume V0 to the first solution pool, and adding an indicating standard solution with a second concentration of volume V0 to the second solution pool to the fourth solution pool respectively; adding a flocculant standard solution to the fifth solution pool; S32, adding the standard solution in the fifth solution pool to the first solution pool to the fourth solution pool at a uniform speed; S33, using an ammeter to detect the current at a certain interval to obtain a current value-flocculant volume relationship curve, and determine the inflection point of the relationship curve; and then obtaining a flocculant concentration-inflection point standard curve; S34, repeating steps S31~S33 to obtain different types of flocculant concentration-inflection point standard curves.

[0013] According to an embodiment of the present disclosure, the machine-made sand to be tested is fully mixed with distilled water in S4, and the pretreatment includes: fully mixing the machine-made sand to be tested with distilled water to obtain a mixed solution; filtering the mixed solution through at least two stainless steel sieves with different pore sizes in sequence to obtain a sample solution to be tested; wherein the pore sizes of the at least two stainless steel sieves with different pore sizes decrease in sequence.

[0014] According to an embodiment of the present disclosure, obtaining the inflection point on the current value-flocculant volume relationship curve in S5 includes: S41, adding an indicator standard solution with a first concentration of volume V0 to the first solution pool, and adding an indicator standard solution with a second concentration of volume V0 to the second solution pool to the fourth solution pool respectively; adding the sample solution to be tested to the fifth solution pool; S42, adding the sample solution to be tested in the fifth solution pool to the first solution pool to the fourth solution pool respectively at a uniform speed; S43, using an ammeter to detect the current at a certain interval to obtain a current value-sample volume relationship curve, and determine the inflection point of the relationship curve.

[0015] According to an embodiment of the present disclosure, obtaining the residual concentration of different types of flocculants in the machine-made sand in S5 includes: S44, determining the corresponding residual concentration of flocculants according to the inflection point and the standard curve; S45, repeating steps S41 to S44, replacing different types of indicator standard solutions, and obtaining different types of flocculant residual concentrations.

[0016] The second aspect of the present disclosure provides a use of the aforementioned rapid detection method for the residual concentration of flocculant in machine-made sand, which is used to determine whether the machine-made sand to be tested can be used to prepare concrete based on the determined residual concentrations of different types of flocculants. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above 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:

[0018] Figure 1 A flowchart schematically shows a method for quickly detecting the residual concentration of flocculant in machine-made sand according to an embodiment of the present disclosure;

[0019] Figure 2 The structure diagram of the detection circuit according to the embodiment of the present disclosure is schematically shown;

[0020] Figure 3 The standard curve of 18 million molecular weight anionic polyacrylamide according to the embodiment of the present disclosure is schematically shown;

[0021] Figure 4 The standard curve of polyaluminium chloride (26%) according to the embodiment of the present disclosure is schematically shown;

[0022] Figure 5 The standard curve of polyferric sulfate according to the embodiment of the present disclosure is schematically shown;

[0023] Figure 6 The relationship curve between the current value I and the volume V of the sample solution added to be tested and the inflection point V on the curve are schematically shown according to the embodiment of the present disclosure. x Schematic diagram of

[0024] Figure 7 Schematically shows the use of the inflection point V according to the embodiment of the present disclosure x Schematic diagram for calculating flocculant concentration;

[0025] Description of reference numerals:

[0026] 1, first solution tank; 2, second solution tank; 3, third solution tank; 4, fourth solution tank; 5, fifth solution tank; 6, electrode; 7, wire; 8, power supply; 9, ammeter; 10, peristaltic pump; 11, hose. DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0028] 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.

[0029] In order to solve the problem that there are residual flocculants in the current machine-made sand, which affects the workability of concrete, a rapid detection method and supporting device for the residual concentration of flocculants in machine-made sand are developed. By detecting the concentration of residual flocculants in the machine-made sand, it is judged whether the machine-made sand can be directly used in the preparation of concrete. For machine-made sand that does not meet the requirements, a suggestion for adjusting the mix ratio is given. The present disclosure aims to improve the quality of machine-made sand on the construction site and ensure the quality of concrete engineering.

[0030] This disclosure provides a method for rapid detection of residual concentration of flocculant in machine-made sand, see Figure 1 , including: S1, preparing different types of indicating standard solutions and different types of flocculant standard solutions of first concentration and second concentration respectively; S2, establishing a detection circuit; the detection circuit includes a first solution pool, a third solution pool, a fourth solution pool, and a second solution pool connected in series in sequence, wherein a power supply is electrically connected to the first solution pool and the second solution pool respectively, and an ammeter is electrically connected to the first solution pool and the fourth solution pool respectively; and a fifth solution pool is connected to pipelines from the first solution pool to the fourth solution pool respectively; S3, using the indicating standard solution, the flocculant standard solution and the detection circuit, obtaining different types of flocculant concentration-inflection point standard curves; wherein the inflection point is the inflection point on the current value-flocculant volume relationship curve; S4, fully mixing and pre-treating the machine-made sand to be tested with distilled water to obtain a sample solution to be tested; S5, using the indicating standard solution, the sample solution to be tested and the detection circuit, obtaining the inflection point on the current value-flocculant volume relationship curve; according to the inflection point and the standard curve, the residual concentration of different types of flocculants in the machine-made sand is obtained.

[0031] The main purpose of the present invention is to provide a rapid detection method and supporting device for the residual concentration of flocculants in machine-made sand, in order to quantitatively evaluate the residual concentration of flocculants in machine-made sand and improve the quality of concrete preparation at the construction site. Since the content and type of flocculants attached to the machine-made sand are unknown, it is difficult to directly detect the type and content of multiple flocculants at the construction site. The method disclosed in the present invention first obtains the standard curves of different types of flocculants, and then determines the residual concentrations of different types of flocculants in the machine-made sand to be tested based on the standard curve based on the same detection circuit.

[0032] Specifically, the present disclosure utilizes the flocculation effect of flocculants on harmful ions or harmful media, and uses the change in solution conductivity to characterize the concentration change of a solution of known concentration, thereby inverting the type of unknown flocculant and the concentration of the flocculant in the solution. This is completely different from the existing test methods for testing the viscosity, absorbance, and turbidity of flocculant aqueous solutions, and is also different from the method for testing the fluidity change of mortar or cement paste, and is an innovative test method. In addition, the detection method involved in the present disclosure is not limited to the need for high-value detection equipment (such as ion chromatographs, spectrophotometers, etc.), nor is it limited to a specific flocculant, and can avoid the influence of impurities attached to machine-made sand on the detection results.

[0033] On the basis of the above embodiment, in S1, the first concentration is greater than the second concentration; the first concentration ranges from 1 g / L to 3 g / L; and the second concentration ranges from 0.01 g / L to 0.03 g / L.

[0034] The selection of two different concentrations of indicating standard solutions utilizes the principle of conductivity difference of the same electrolyte under different concentration conditions. When the concentration is high, the solution conductivity is high, the resistance is small, and the current in the circuit is large; when the concentration is low, the solution conductivity is low, the resistance is large, and the current in the circuit is small. Among them, the indicating standard solution of the first concentration is used for indication, and the indicating standard solution of the second concentration is used for detection. When the two are used together, the sample solution of unknown concentration is mixed with the indicating standard solutions of two concentrations, and the flocculant reacts with the ions in the standard solution, causing the concentration of the standard solution to decrease, the conductivity to increase, the resistivity to decrease, and the current in the circuit to decrease. However, since the concentration of the first concentration standard solution is much higher than that of the second concentration standard solution, when the ions in the second concentration standard solution are completely consumed by the flocculant, when the sample to be tested is added, the flocculant can no longer be consumed by the reaction, resulting in a relative increase in concentration, an increase in current, and an inflection point.

[0035] Based on the above embodiments, the different types of indicator standard solutions in S1 include one or more of copper sulfate solution, copper chloride solution, silver nitrate solution, potassium thiocyanate solution, ferric hydroxide colloid, and starch solution; the different types of flocculant standard solutions include one or more of anionic polyacrylamide, polyaluminum chloride, and polyferric sulfate.

[0036] Copper sulfate solution reacts with anionic polyacrylamide (18 million molecular weight), resulting in a decrease in ion concentration in the solution and a decrease in the current value. When the reaction is complete, the sample to be tested is continued to be added, and the flocculant exists freely in the solution, resulting in a relative increase in the concentration of conductive ions in the solution, and a sudden change in the current value occurs; silver nitrate solution reacts with polyaluminium chloride (26%), resulting in a decrease in ion concentration in the solution and a decrease in the current value. When the reaction is complete, the sample to be tested is continued to be added, and the flocculant exists freely in the solution, resulting in a relative increase in the concentration of conductive ions in the solution, and a sudden change in the current value occurs; ferric hydroxide colloid reacts with polymerised ferric sulfate, resulting in the colloid with colloidal particles flocculating, the concentration of conductive particles is reduced, and the current value is reduced. When the reaction is complete, the sample to be tested is continued to be added, and the flocculant exists freely in the solution, resulting in a relative increase in the concentration of conductive ions in the solution, and a sudden change in the current value occurs. Of course, the indicator standard solution and the flocculant standard solution can also be other types of solutions, as long as the technical effects of the present disclosure can be achieved.

[0037] On the basis of the above embodiment, the fifth solution pool in S2 is connected to the first solution pool to the fourth solution pool through a hose and a peristaltic pump respectively; the flow rate of the liquid added by the peristaltic pump is 50-100 ml / min.

[0038] Figure 2 The schematic diagram of the detection circuit in the present disclosure is shown, including: a first solution pool 1, a second solution pool 2, a third solution pool 3, a fourth solution pool 4, a fifth solution pool 5, an electrode 6, a wire 7, a power supply 8, an ammeter 9, a peristaltic pump 10, a hose 11 and a single chip. The power supply 8 is a voltage-regulated power supply with an adjustable voltage of 0-20V. The first solution pool 1, the second solution pool 2, the third solution pool 3, and the fourth solution pool 4 are connected in series using a wire. The positive electrode of the power supply 8 is connected to the positive electrode of the first solution pool 1, and the negative electrode of the power supply 8 is connected to the negative electrode of the second solution pool 2; the positive electrode of the ammeter 9 (with an accuracy of 1μA) is connected to the negative electrode of the first solution pool 1, and the negative electrode of the ammeter 9 is connected to the positive electrode of the fourth solution pool 4. The fifth solution pool 5 is connected to the first solution pool 1, the second solution pool 2, the third solution pool 3, and the fourth solution pool 4 via a hose 11 and a peristaltic pump 10, respectively. Among them, the use of a peristaltic pump can effectively ensure that the liquid in the fifth solution pool can be added to the first solution pool to the fourth solution pool at a uniform speed, which is beneficial to the subsequent drawing of a standard curve.

[0039] On the basis of the above embodiment, the detection circuit in S2 further includes a single chip microcomputer for analyzing the concentration of the flocculant.

[0040] When the standard solution in the fifth solution pool is added to the first solution pool to the fourth solution pool at a uniform speed, the single chip microcomputer is used to record the current value and the dripping volume, draw the current-added solution volume curve, determine the inflection point on the curve, and then draw different types of flocculant concentration-inflection point standard curves.

[0041] On the basis of the above embodiment, different types of flocculant concentration-inflection point standard curves obtained in S3 include: S31, adding a first concentration indicator standard solution with a volume of V0 to the first solution pool, and adding a second concentration indicator standard solution with a volume of V0 to the second solution pool to the fourth solution pool; adding a flocculant standard solution to the fifth solution pool; S32, adding the standard solution in the fifth solution pool to the first solution pool to the fourth solution pool at a uniform speed; S33, using an ammeter to detect the current at a certain interval to obtain a current value-flocculant volume relationship curve, and determine the inflection point of the relationship curve; and then obtaining a flocculant concentration-inflection point standard curve; S34, repeating steps S31 to S33 to obtain different types of flocculant concentration-inflection point standard curves.

[0042] Taking the flocculant standard solution with a standard concentration of 0.003% to 0.033% as an example, the drawing of the standard curve of the present disclosure is explained. During the test, 18 million molecular weight anionic polyacrylamide, 26% polyaluminium chloride and polyferric sulfate aqueous solution with a concentration of 0.003% to 0.033% (concentration step of 0.006%) are injected into the fifth solution pool, and the labeled numbers X and i (i=1,2,3) A portion of the indicating standard solution with a higher concentration is injected into the first solution pool of the detection circuit, and another 3 portions of the indicating standard solution with the same number but a lower concentration are injected into the second solution pool, the third solution pool and the fourth solution pool of the detection circuit. When the power is turned on, the single-chip microcomputer immediately records the initial output current value I1 of the ammeter; the peristaltic pump is turned on to add the standard concentration flocculant standard solution in the fifth solution pool to the first solution pool, the second solution pool, the third solution pool and the fourth solution pool. After each 5ml is added, the output current value I2 of the ammeter is recorded; the relationship curve between the output current value I of the ammeter and the volume V of the sample with the standard concentration flocculant added is drawn using the single-chip microcomputer, and the inflection point V on the curve is determined φ , and then draw to obtain the flocculant concentration Φ i With inflection point V φ The relationship curve is the standard curve.

[0043] On the basis of the above embodiment, the machine-made sand to be tested is fully mixed with distilled water in S4, and the pretreatment includes: fully mixing the machine-made sand to be tested with distilled water to obtain a mixed solution; filtering the mixed solution through at least two stainless steel sieves with different pore sizes in turn to obtain a sample solution to be tested; wherein the pore sizes of the at least two stainless steel sieves with different pore sizes are reduced in turn.

[0044] Distilled water is used to mix with the machine-made sand to be tested to better dissolve the flocculant remaining on the machine-made sand to be tested. Multiple filtrations of the mixed solution are beneficial to better remove the machine-made sand solids and avoid affecting the subsequent detection process. Preferably, the sand washing wastewater to be tested is sequentially passed through 200 mesh, 300 mesh, 500 mesh and 1000 mesh stainless steel sieves to obtain the sample solution to be tested.

[0045] On the basis of the above-mentioned embodiment, the inflection point on the current value-flocculant volume relationship curve is obtained in S5, including: S41, adding an indicating standard solution with a first concentration of volume V0 to the first solution pool, and adding an indicating standard solution with a second concentration of volume V0 to the second solution pool to the fourth solution pool respectively; adding the sample solution to be tested to the fifth solution pool; S42, adding the sample solution to be tested in the fifth solution pool to the first solution pool to the fourth solution pool respectively at a uniform speed; S43, using an ammeter to detect the current at a certain interval to obtain a current value-sample volume relationship curve, and determine the inflection point of the relationship curve.

[0046] Take the marker number X i (i=1,2,3) A portion of the indicating standard solution with a higher concentration is injected into the first solution pool of the detection circuit, and another 3 portions of the indicating standard solution with the same number but lower concentration are injected into the second solution pool, the third solution pool and the fourth solution pool of the detection circuit. Take a sufficient amount of the sample of the solution to be tested and add it to the fifth solution pool, and then start the test. After the power is turned on, the single-chip microcomputer immediately records the initial output current value I1 of the ammeter; start the peristaltic pump, and add the sample of the solution to be tested in the fifth solution pool to the first solution pool, the second solution pool, the third solution pool and the fourth solution pool. After each 10ml is added, record the output current value I2 of the ammeter; use the single-chip microcomputer to draw a relationship curve between the output current value I of the ammeter and the volume V of the sample of the solution to be tested, and determine the inflection point V on the curve x .

[0047] On the basis of the above embodiment, obtaining the residual concentration of different types of flocculants in the machine-made sand in S5 includes: S44, determining the corresponding residual concentration of flocculants according to the inflection point and the standard curve; S45, repeating steps S41 to S44, replacing different types of indicator standard solutions, and obtaining different types of flocculant residual concentrations.

[0048] Furthermore, V x Substitute it into the standard curve built into the microcontroller to determine the flocculant concentration Φ in the sample to be tested. Specifically, the flocculant residual concentration Φ0 in the sand-making sample is calculated based on the flocculant concentration Φ in the sample to be tested. If the mass ratio of the machine-made sand to distilled water is 1:2, then Φ0=2×Φ.

[0049] The present disclosure also provides a use of the aforementioned rapid detection method for the residual concentration of flocculant in machine-made sand, which is used to determine whether the machine-made sand to be tested can be used to prepare concrete based on the determined residual concentrations of different types of flocculants.

[0050] According to the residual concentration Φ0 and threshold Φ of flocculant in machine-made sand θ1 and Φ θ2 Considerations when determining the use of machine-made sand to prepare concrete:

[0051] For Φ0<Φ θ1 The machine-made sand can be directly used to prepare concrete.

[0052] For Φ θ1 ≤Φ0<Φ θ2 The machine-made sand in this batch reminds technicians that when using this batch of machine-made sand to prepare concrete, they need to adjust the amount of water reducer in the mix ratio in time to ensure the fluidity and pumpability of the concrete.

[0053] For Φ0≥Φ θ2 The machine-made sand in the batch cannot be used directly to prepare concrete, and needs to be cleaned twice in the engineering phenomenon to reduce the concentration of residual flocculant in the machine-made sand and wait for re-testing.

[0054] Specifically, for example, the flocculant threshold value Φ for determining whether machine-made sand can be directly used to prepare concrete is θ1 is 0.018%, the threshold Φ θ2 It is 0.054%.

[0055] The present disclosure is further described below through specific implementation methods. The rapid detection method and use of the residual concentration of flocculant in the above-mentioned machine-made sand are specifically described in the following examples. However, the following examples are only used to illustrate the present disclosure, and the scope of the present disclosure is not limited thereto.

[0056] The rapid detection method of the residual concentration of flocculant in the machine-made sand of this embodiment comprises the following steps:

[0057] (1) Prepare the machine-made sand sample. Mix the machine-made sand sample with distilled water in a mass ratio of 1:2. Then filter it through stainless steel sieves of 200 mesh, 300 mesh, 500 mesh and 1000 mesh in sequence to obtain the solution sample to be tested.

[0058] (2) Prepare three indicator standard solutions numbered X i (i=1,2,3): X1: copper sulfate solution, X2: silver nitrate solution, X3: ferric hydroxide colloid. Prepare two concentrations of the three indicating standard solutions, one with a higher concentration of 1g / L~3g / L and the other with a lower concentration of 0.01g / L~0.03g / L;

[0059] (3) Prepare the detection circuit. The detection circuit includes the first solution pool, the second solution pool, the third solution pool, the fourth solution pool, the fifth solution pool, electrodes, wires, power supply, ammeter, peristaltic pump, hose and single chip microcomputer. The detection circuit is built as follows:

[0060] Prepare a voltage-regulated power supply with adjustable voltage of 0~20V, connect the first solution pool, the second solution pool, the third solution pool, and the fourth solution pool in series with copper wires, connect the positive electrode of the first solution pool to the positive electrode of the power supply, connect the negative electrode of the second solution pool to the negative electrode of the power supply, and connect an ammeter (with an accuracy of 1μA) between the negative electrode of the first solution pool and the positive electrode of the fourth solution pool. Use a hose to connect the first solution pool, the second solution pool, the third solution pool, the fourth solution pool, and the fifth solution pool, set up a peristaltic pump in the middle, and adjust the peristaltic pump flow rate to 5~50ml / min.

[0061] (4) Take the marker number X i (i=1,2,3) A portion of the higher concentration standard solution is injected into the first solution pool of the detection circuit, and another 3 portions of the same number but lower concentration standard solution are injected into the second solution pool, the third solution pool, and the fourth solution pool of the detection circuit. Take a sufficient amount of the solution sample to be tested and add it to the fifth solution pool.

[0062] (5) When the power is turned on, the microcontroller immediately records the initial output current value I1 of the ammeter;

[0063] (6) Turn on the peristaltic pump and add the solution sample to be tested in the fifth solution tank to the first solution tank, the second solution tank, the third solution tank, and the fourth solution tank. After each 5 ml is added, record the current value I2 output by the ammeter;

[0064] (7) Use the single-chip computer to draw a curve to obtain the relationship between the output current value I of the ammeter and the volume V of the sample solution added to the test solution, and determine the inflection point V on the curve x ;

[0065] (8) V x Substitute it into the standard curve built into the microcontroller to determine the flocculant concentration Φ in the sample to be tested;

[0066] The standard curve built into the single-chip microcomputer is obtained by using the above method to replace the test solution with the standard concentration of flocculant standard solution, that is, using 18 million molecular weight anionic polyacrylamide, 26% polyaluminum chloride, and polyferric sulfate aqueous solution with a standard concentration of 0.003%~0.033% (concentration step of 0.006%) to replace the test solution sample in the fifth solution pool, respectively, and using the single-chip microcomputer to draw the relationship curve between the output current value I of the ammeter and the volume V of the sample with the standard concentration of flocculant added, and determine the inflection point V on the curve φ , and then draw to obtain the flocculant concentration Φ i With inflection point Vφ The relationship curve is the standard curve. Figure 3 The standard curve of 18 million molecular weight anionic polyacrylamide is shown; Figure 4 The standard curve of polyaluminium chloride (26%) is shown; Figure 5 A standard curve for polyferric sulfate is shown.

[0067] (9) The method for calculating the residual concentration Φ0 of the flocculant in the sand making sample according to the flocculant concentration Φ in the sample to be tested is as follows:

[0068] Φ0=2×Φ.

[0069] (10) According to the flocculant concentration Φ0 and threshold Φ θ1 and Φ θ2 Determine the precautions when using machine-made sand to prepare concrete;

[0070] For Φ0<Φ θ1 The machine-made sand can be directly used to prepare concrete.

[0071] For Φ θ1 ≤Φ0<Φ θ2 The machine-made sand in this batch reminds technicians that when using this batch of machine-made sand to prepare concrete, they need to adjust the amount of water reducer in the mix ratio in time to ensure the fluidity and pumpability of the concrete.

[0072] For Φ≥Φ θ2 The machine-made sand in the batch cannot be used directly to prepare concrete, and needs to be cleaned twice at the construction site to reduce the concentration of residual flocculant in the machine-made sand and wait for re-testing.

[0073] In the above scheme, the threshold Φ θ1 is 0.018%, the threshold Φ θ2 It is 0.054%.

[0074] In this embodiment, combined with the previous test research on the detection of artificial sand containing anionic polyacrylamide, the solution sample to be tested is obtained according to the description in the specific implementation plan, and further tests are performed to obtain the current values ​​I1 and I2, as well as the corresponding volume of the injected solution, as shown in Table 1.

[0075] Table 1 Test current values ​​and test solution sample filling volumes

[0076]

[0077] Plot Table 1, such as Figure 6 As shown, the inflection point V of the current value-flocculant volume relationship curve is obtained. x The value corresponds to 90ml.

[0078] The inflection point Vx Value Substitution Figure 3 The standard curve in Figure 7 As shown, the flocculant concentration value Φ in the sample to be tested is 0.0185%, and the residual flocculant concentration Φ0 in the machine-made sand sample is calculated to be 0.037%.

[0079] According to the threshold Φ θ1 :0.018% and Φ θ2 :0.054%, and the residual concentration of flocculant Φ0 is 0.037%, which is judged to be Φ θ1 ≤Φ0<Φ θ2 The machine-made sand in this batch reminds technicians that when using this batch of machine-made sand to prepare concrete, they need to adjust the amount of water reducer in the mix ratio in time to ensure the fluidity and pumpability of the concrete.

[0080] In summary, the present disclosure provides a rapid detection method and supporting device for the residual concentration of flocculant in machine-made sand, which takes into account the comprehensive detection requirements when multiple types of flocculants exist in the machine-made sand, as well as the influence of other impurities contained in the machine-made sand on the detection results. Based on the principle of solution conductivity that has not been used yet, the detection of the residual flocculant concentration in the machine-made sand at the engineering site is realized, and suggestions for the use of machine-made sand with different residual flocculant concentrations are given. Therefore, the present disclosure has at least the following beneficial effects:

[0081] 1. The present disclosure has a significant effect in improving detection accuracy. The method proposed in the present disclosure can meet the residual concentration detection of various types of flocculants in machine-made sand, and the detection accuracy can be improved to a concentration of 0.01%. At the same time, the present disclosure utilizes the flocculation effect of flocculants on harmful ions or harmful media, and uses the change in solution conductivity to characterize the concentration change of a solution of known concentration, and then inverts the unknown flocculant type and flocculant concentration in the solution. This is completely different from the existing methods of testing the viscosity, absorbance, turbidity, etc. of aqueous solutions, and is also different from the existing methods of testing the fluidity of freshly mixed mortar. In addition, since the method of the present disclosure uses a bridge connection method to test the change in solution conductivity, it shields the influence of other impurities, moisture and turbidity changes of the solution sample to be tested on the machine-made sand, thereby further improving the detection accuracy.

[0082] 2. The present disclosure has a significant effect in improving detection efficiency and reducing technical requirements. The method and supporting device proposed in the present disclosure only need to build the corresponding components once, and can repeatedly carry out multiple detection work, and only requires technicians to take samples to make sand and prepare samples of the solution to be tested. The rest of the operations can be completed by the device itself, which greatly improves the detection efficiency and reduces the need for professional training for technicians, thereby reducing the detection errors caused by human subjective factors.

[0083] 3. The present disclosure has a significant effect in reducing the cost of testing. The method proposed in the present disclosure and the supporting device developed are extremely low in cost, and the main cost comes from the preparation of analytical pure samples of various standard reagents, which is extremely small compared to the cost of using expensive equipment such as spectrophotometers and liquid chromatographs, and can meet the cost investment of construction site laboratories, and has broad prospects for promotion and application.

[0084] 4. The present disclosure has a significant effect in saving resources. The method proposed in the present disclosure can detect the concentration of residual flocculants in machine-made sand, and prompt on-site technicians to adjust the concrete mix ratio in time, which has not been mentioned in similar disclosures. The application of related technologies can further improve the utilization rate of machine-made sand, while reducing the insufficient performance of concrete caused by machine-made sand quality problems, thereby avoiding the waste of raw material resources.

[0085] 5. This disclosure plays a positive role in promoting the quality control of machine-made sand. By realizing rapid detection of the residual flocculant concentration in machine-made sand at the construction site, it provides a convenient and practical method for owners and supervisors, which helps to strengthen the supervision and management of the quality of machine-made sand before the industry provides standardized detection methods.

[0086] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above description is only a specific embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A rapid detection method for residual flocculant concentration in machine-made sand, characterized in that: include: S1, preparing different types of indicator standard solutions and different types of flocculant standard solutions of first concentration and second concentration, respectively; S2, establishing a detection circuit; the detection circuit comprises a first solution pool, a third solution pool, a fourth solution pool, and a second solution pool connected in series in sequence, wherein a power supply is electrically connected to the first solution pool and the second solution pool, respectively, an ammeter is electrically connected to the first solution pool and the fourth solution pool, respectively; and a fifth solution pool is connected to pipelines from the first solution pool to the fourth solution pool, respectively; S3, using the indicator standard solution, the flocculant standard solution and the detection circuit, obtaining different types of flocculant concentration-inflection point standard curves; wherein the inflection point is an inflection point on the current value-flocculant volume relationship curve; S4, fully mixing and pre-treating the machine-made sand to be tested with distilled water to obtain a sample solution to be tested; S5, using the indicator standard solution, the sample solution to be tested and the detection circuit, obtaining an inflection point on a current value-flocculant volume relationship curve; and obtaining residual concentrations of different types of flocculants in the machine-made sand according to the inflection point and the standard curve; Wherein, the concentration-inflection point standard curves of different types of flocculants obtained in S3 include: S31, adding a first concentration indicator standard solution with a volume of V0 to the first solution pool, adding a second concentration indicator standard solution with a volume of V0 to the second solution pool to the fourth solution pool respectively; adding a flocculant standard solution to the fifth solution pool; S32, adding the standard solution in the fifth solution pool to the first solution pool to the fourth solution pool at a uniform speed; S33, using the ammeter to detect the current at a certain interval, obtain a current value-flocculant volume relationship curve, determine the inflection point of the relationship curve; and then obtain a flocculant concentration-inflection point standard curve; S34, repeating the steps S31 to S33 to obtain different types of flocculant concentration-inflection point standard curves.

2. The rapid detection method for residual flocculant concentration in machine-made sand according to claim 1 is characterized in that: In S1, the first concentration is greater than the second concentration; The first concentration ranges from 1 g / L to 3 g / L; the second concentration ranges from 0.01 g / L to 0.03 g / L.

3. The rapid detection method for residual flocculant concentration in machine-made sand according to claim 1 is characterized in that: The different types of indicator standard solutions described in S1 include one or more of copper sulfate solution, copper chloride solution, silver nitrate solution, potassium thiocyanate solution, ferric hydroxide colloid, and starch solution; The different types of flocculant standard solutions include one or more of anionic polyacrylamide, polyaluminium chloride and polyferric sulfate.

4. The rapid detection method for residual flocculant concentration in machine-made sand according to claim 1 is characterized in that: The fifth solution tank in S2 is connected to the first solution tank to the fourth solution tank through a hose and a peristaltic pump respectively; The flow rate of the peristaltic pump adding liquid is 50-100 ml / min.

5. The rapid detection method for residual flocculant concentration in machine-made sand according to claim 1 is characterized in that: The detection circuit in S2 further includes a single chip microcomputer for analyzing the concentration of the flocculant.

6. The rapid detection method for residual flocculant concentration in machine-made sand according to claim 1, characterized in that: The pretreatment of fully mixing the machine-made sand to be tested with distilled water as described in S4 includes: Fully mix the machine-made sand to be tested with distilled water to obtain a mixed solution; The mixed solution is filtered through at least two stainless steel meshes with different pore sizes in sequence to obtain a sample solution to be tested; wherein the pore sizes of the at least two stainless steel meshes with different pore sizes decrease in sequence.

7. The rapid detection method for residual flocculant concentration in machine-made sand according to claim 1, characterized in that: The inflection points on the current value-flocculant volume relationship curve obtained in S5 include: S41, adding a first concentration indicator standard solution with a volume of V0 to the first solution pool, adding a second concentration indicator standard solution with a volume of V0 to the second solution pool to the fourth solution pool respectively; adding a sample solution to be tested to the fifth solution pool; S42, adding the sample solution to be tested in the fifth solution pool to the first solution pool to the fourth solution pool at a uniform speed respectively; S43, using the ammeter to detect the current at regular intervals, obtaining a current value-to-test sample volume relationship curve, and determining the inflection point of the relationship curve.

8. The rapid detection method for residual flocculant concentration in machine-made sand according to claim 7, characterized in that: The residual concentrations of different types of flocculants in the machine-made sand obtained in S5 include: S44, determining the corresponding flocculant residual concentration according to the inflection point and the standard curve; S45, repeating the steps S41 to S44, replacing the different types of indicator standard solutions, and obtaining different types of flocculant residual concentrations.

9. Use of the method for rapid detection of residual flocculant concentration in machine-made sand according to any one of claims 1 to 8, for judging whether the machine-made sand to be tested can be used for preparing concrete based on the determined residual concentrations of different types of flocculants.

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