CN111504840A - Method for detecting zinc content of galvanized waste steel - Google Patents
Method for detecting zinc content of galvanized waste steel Download PDFInfo
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- CN111504840A CN111504840A CN202010041601.2A CN202010041601A CN111504840A CN 111504840 A CN111504840 A CN 111504840A CN 202010041601 A CN202010041601 A CN 202010041601A CN 111504840 A CN111504840 A CN 111504840A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N5/00—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid
- G01N5/04—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid by removing a component, e.g. by evaporation, and weighing the remainder
Abstract
The invention discloses a method for detecting zinc content of galvanized steel scrap, and belongs to the technical field of metal content detection. Dissolving a zinc coating in a test solution with a corrosion inhibition effect, wherein hexamethylenetetramine is added in the preparation process of the test solution with the corrosion inhibition effect and then diluted; and weighing the mass of the sample before and after the coating is dissolved, and calculating the mass of the zinc plating on the unit area according to the weighed difference and the sample area. The invention has the advantages of improved detection precision, lower detection cost and better feasibility.
Description
Technical Field
The invention relates to the technical field of metal content detection, in particular to a method for detecting the zinc content of galvanized waste steel.
Background
The global production of galvanized sheet coils is continuously increased, the global production is 1.208 million tons in 2014, 5070 million tons of galvanized sheet coils are produced in China, the global production of 2016 reaches 1.55 million tons, and the steel scrap company has a large quantity of higher zinc-containing scrap, so that the zinc content of steel-making OG mud is high. Meanwhile, the steel-making OG mud of the first and fourth steel rolling factories of the steel works company and the long material business department is recycled and added into the blast furnace for cyclic utilization in the sintering process, so that the zinc load of the blast furnace is increased, and the stability and the smoothness of the blast furnace are influenced, so the importance of dezincification of the scrap steel is particularly urgent. Because the zinc-containing waste steel has more types and different zinc contents of different waste steels due to different processes, the establishment of the zinc content evaluation method of the galvanized waste steel is very difficult.
The accurate evaluation of the zinc content in the scrap steel has important value on the stability of the steel production process, and the accurate evaluation of the zinc content is mainly solved by how to sample, the sample is representative, and the test result can be accurate. Through on-site investigation, the galvanized steel scraps of the existing steel scrap company have a plurality of types, and the analysis workload is large from the types of the galvanized steel scraps, so that the zinc content of the steel scraps is not easy to quickly evaluate. The number of objects of each type of galvanized scrap is very different and simple random sampling does not adequately represent the less frequently occurring object types, which can be problematic when the analysis requires all types of representatives.
At present, the detection of the zinc content in the coating of the galvanized steel sheet discloses a few technologies, and only detection methods of other metal elements exist, such as Chinese patent application: the patent name is 'a method for rapidly detecting the content of lead and cadmium in a galvanized steel sheet coating', the publication date is 2017, 3, 29 and the publication number is CN106546573A, the method for detecting the content of lead and cadmium disclosed by the patent comprises the steps of firstly establishing a calibration working curve of each element including Pb and Cd elements according to a standard sample; analyzing the detected galvanizing sample by calibrating a working curve, measuring to obtain a relation curve of each layer of Fe, Zn, Pb and Cd element components changing along with the thickness of the plating layer, defining the depth of the plating layer and the mass integral depth of the detected elements Pb and Cd, and obtaining the integral mass of the depth of the Pb and Cd element plating layer; and integrating the mass fraction of the elements by time or the thickness of the coating in the depth of the coating, converting the function of the time into a function of the depth, adding the coating mass of all the elements, and dividing the coating mass of each element of Pb and Cd by the total coating mass to obtain the average mass fraction of the elements of Pb and Cd in the coating. The galvanized steel plate coating does not need to be stripped or dissolved by a chemical method, although the technical scheme of the patent can measure the contents of Pb and Cd elements in the coating; however, the result of detecting the zinc content in the zinc coating by adopting the method is difficult to ensure, and the detection cost and efficiency are low.
Disclosure of Invention
1. Technical problem to be solved by the invention
The invention aims to provide a method for detecting the zinc content of galvanized steel scrap, aiming at solving the technical problems of inaccurate detection of the zinc content of the steel scrap and high detection cost in the prior art. The method has the advantages that hexamethylenetetramine is added in the preparation process of the test solution with the corrosion inhibition effect, and then dilution is carried out, so that the detection accuracy of the zinc content in the scrap steel is improved.
2. Technical scheme
In order to achieve the purpose, the technical scheme provided by the invention is as follows:
the invention relates to a method for detecting zinc content in galvanized steel scrap, which is characterized in that a zinc coating is dissolved in a test solution with a corrosion inhibition effect, wherein hexamethylenetetramine is added in the preparation process of the test solution with the corrosion inhibition effect and then diluted; weighing the mass of the sample before and after the coating is dissolved, and calculating the galvanizing mass in unit area according to the weighed difference and the sample area; in the preparation process of the test solution with the corrosion inhibition effect, hexamethylenetetramine is added firstly and then diluted, so that excessive dissolution of a sample is avoided, the sample dissolution effect is improved, and the detection accuracy is improved.
Preferably, the specific steps are as follows:
(1) dissolving hexamethylenetetramine in concentrated hydrochloric acid, and diluting the hexamethylenetetramine by using a diluent to prepare a test solution;
(2) cleaning oil stains, dust, water stains and the like on the surface of the sample, fully drying, and weighing the sample by using balance;
(3) immersing the sample into the test solution until the coating is completely dissolved, taking out the dissolved test, drying and weighing;
(4) and calculating the zinc plating quality in unit area according to the weighed difference and the sample area.
Preferably, the concentrated hydrochloric acid density ρ in step (1) is 1.19g/m L.
Preferably, the diluent in step (1) is distilled water or deionized water.
Preferably, the weighing accuracy in the step (2) is up to 1% of the expected mass of the zinc of the sample, and when the mass of the coating of the sample is not less than 0.1g, the weighing accuracy is up to 0.001 g.
Preferably, the amount of test solution used in step (2) is generally not less than 10m L per square centimeter of sample surface area.
Preferably, the end of the hydrogen gas significant precipitation is judged in step (3) as the end of the dissolution process.
Preferably, the calculation method in step (4) is:
and (4) calculating the zinc content of the waste galvanized sheet according to a formula.
In the formula:
m-galvanized coating mass per unit area (double-sided), in grams per square meter (g/M)2)；
m1The mass of the galvanized layer of the sample before dissolution is in grams (g);
m2the mass of the galvanized layer of the sample after dissolution is expressed in grams (g);
a is the area of the sample. In units of square millimeters (mm)2)。
Compared with the prior art, the technical scheme provided by the invention has the advantages of high detection precision, lower detection cost and better feasibility.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments; moreover, the embodiments are not relatively independent, and can be mutually combined according to requirements, so that a better effect is achieved. Thus, the following detailed description of the embodiments of the invention is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
The accurate evaluation of the zinc content in the scrap steel has important value on the stability of the steel production process, and the accurate evaluation of the zinc content is mainly solved by how to sample, the sample is representative, and the test result can be accurate. Through on-site investigation, the galvanized steel scraps of the existing steel scrap company have a plurality of types, and the analysis workload is large from the types of the galvanized steel scraps, so that the zinc content of the steel scraps is not easy to quickly evaluate. The number of objects of each type of galvanized scrap is very different and simple random sampling does not adequately represent the less frequently occurring object types, which can be problematic when the analysis requires all types of representatives. Therefore, classified sampling and layered sampling which are suitable for large overall quantity and large difference degree are selected and applied to the research through research.
According to the results of on-site investigation, the galvanized steel scraps of the horse steel are mainly divided into two shapes, namely broken materials and galvanized sheet briquettes. According to the characteristics, the galvanized steel scraps are divided into: crushing material A and galvanized sheet B; the crushed material A comprises three samples in upper, middle and lower regions according to the height of a material pile; three samples were taken for the galvanized sheet B according to the thickness, and the crushed material and the galvanized sheet were evaluated separately.
The cross section structure of the waste galvanized plate is a zinc oxide layer, a pure zinc layer, a zinc-iron compound layer and a steel matrix layer, wherein the pure zinc layer accounts for most of the whole coating. The zinc coating on the known surface area is dissolved in a test solution with a corrosion inhibition effect, the mass of the test sample before and after the coating is dissolved is weighed, and the zinc coating mass on the unit area is calculated according to the weighed difference and the sample area. After the waste galvanized sheet is subjected to dezincification treatment at high temperature by utilizing the low boiling point of zinc, most of zinc on the surface of the galvanized sheet is evaporated and separated from the body, the other part of zinc is diffused into a steel matrix, and the exposed steel matrix is oxidized after the dezincification is finished, namely the cross-sectional structure of the galvanized sheet after the dezincification is finished is an iron oxide layer and a steel matrix layer containing zinc. The iron oxide on the surface was reduced with carbon monoxide at a high temperature to obtain a sample containing only an iron matrix and zinc. And weighing the mass of the sample before dezincification and the mass of the sample after carbon monoxide reduction after dezincification, wherein the difference value of the mass of the sample before dezincification and the mass of the sample after carbon monoxide reduction after dezincification is the zinc mass of the galvanized sheet after dezincification is finished.
Example 1
Test materials: cleaning solution, analytically pure absolute ethyl alcohol, analytically pure sodium carbonate and analytically pure hexamethylenetetramine (C)6H12N4) And concentrated hydrochloric acid.
3.5g of analytically pure hexamethylenetetramine (C)6H12N4) Dissolving in 500m L concentrated hydrochloric acid (rho is 1.19g/m L), diluting with distilled water or deionized water to 1000m L, wherein the sample is waste galvanized sheet and has unit area of 3000mm2～5000mm2。
Before treatment, surface dirt such as oil stain, dust, rust and the like is removed. The treatment mode adopts gasoline treatment firstly and alcohol or methanol post-treatment to remove surface oil stains, and adopts ultrasonic wave to clean rust and dust. In the embodiment, oil stains, dust, water stains and the like on the surface of the sample are cleaned by using the cleaning solution and then sufficiently dried; weighing the sample by using balance, wherein the weighing accuracy of the sample is up to 1% of the expected zinc quality of the sample, and when the coating quality of the sample is not less than 0.1g, the weighing accuracy is up to 0.001 g; the sample was immersed in the test solution (3.5g of analytically pure hexamethylenetetramine (C)6H12N4) Dissolving in 500m L concentrated hydrochloric acid (. rho. ═ 1.19g/m L), diluting with distilled or deionized water to 1000m L), the test solution is usually used in an amount of not less than 10m L per square centimeter of sample surface area, and the sample is completely immersed in the solution at room temperatureIn the solution, the samples were turned over until the coating was completely dissolved, and the end of the dissolution was judged by the apparent cessation of hydrogen evolution (vigorous bubbling). The sample was then taken out and washed in running water, and if necessary, loose attachments possibly adsorbed on the surface of the sample were brushed off with a nylon brush. Finally, cleaning with ethanol, quickly drying, or absorbing water with absorbent paper, and quickly drying with hot air; the samples were weighed with balance.
And (4) calculating the zinc content of the waste galvanized sheet according to a formula.
In the formula:
m-galvanized coating mass per unit area (double-sided), in grams per square meter (g/M)2)；
m1The mass of the galvanized layer of the sample before dissolution is in grams (g);
m2the mass of the galvanized layer of the sample after dissolution is expressed in grams (g);
a-area of sample in square millimeters (mm)2)。
Measurement test step for zinc content of waste galvanized plate after dezincification
And (3) placing the sample subjected to fire dezincification of the waste galvanized plate in carbon monoxide for reduction at 900 ℃, so that iron oxide on the surface of the sample is reduced into an iron simple substance. And weighing the mass of the waste galvanized sheet before dezincification and the mass of the sample after reduction after dezincification.
The zinc content of the waste galvanized sheet in unit area before dezincification is calculated according to a formula.
In the formula:
m-mass of zinc per unit area after dezincification, in grams per square meter (g/M)2)；
m 1-mass of sample before dezincification, in grams (g);
m 2-mass in grams (g) after dezincification and reduction of the sample;
a-area of sample in square millimeters (mm)2)。
The invention has been described in detail hereinabove with reference to specific exemplary embodiments thereof. It will, however, be understood that various modifications and changes may be made without departing from the scope of the invention as defined in the appended claims. The detailed description is to be construed as illustrative only and not restrictive, and any such modifications and variations are intended to be included within the scope of the invention as described herein. Furthermore, the background is intended to be illustrative of the state of the art as developed and the meaning of the present technology and is not intended to limit the scope of the invention or the application and field of application of the invention.
Claims (8)
1. A zinc content detection method of galvanized steel scrap is characterized in that a zinc coating is dissolved in a test solution with a corrosion inhibition effect, wherein hexamethylenetetramine is added in the preparation process of the test solution with the corrosion inhibition effect and then diluted; and weighing the mass of the sample before and after the coating is dissolved, and calculating the galvanizing mass in unit area according to the weighed difference and the sample area.
2. The method for detecting the zinc content in the galvanized steel scrap according to claim 1, which is characterized by comprising the following specific steps of:
(1) dissolving hexamethylenetetramine in concentrated hydrochloric acid, and diluting the hexamethylenetetramine by using a diluent to prepare a test solution;
(2) cleaning oil stains, dust, water stains and the like on the surface of the sample, fully drying, and weighing the sample by using balance;
(3) immersing the sample into the test solution until the coating is completely dissolved, taking out the dissolved test, drying and weighing;
(4) and calculating the zinc plating quality in unit area according to the weighed difference and the sample area.
3. The method for detecting the zinc content in the galvanized steel scrap according to claim 2, wherein the density p of the concentrated hydrochloric acid in the step (1) is 1.19g/m L.
4. The method for detecting the zinc content in the galvanized steel scrap according to claim 2, wherein the diluent in the step (1) is distilled water or deionized water.
5. The method for detecting the zinc content in the galvanized steel scrap according to claim 2, wherein the weighing accuracy in the step (2) is up to 1% of the expected mass of the zinc in the sample, and when the mass of the coating of the sample is not less than 0.1g, the weighing accuracy is up to 0.001 g.
6. The method for detecting the zinc content in the galvanized steel scrap according to claim 2, wherein the amount of the test solution used in the step (2) is generally not less than 10m L per square centimeter of surface area of the test sample.
7. The method for detecting the zinc content in the galvanized steel scrap according to claim 2, wherein the end of the dissolution process is judged as the end of the hydrogen gas obvious precipitation in the step (3).
8. The method for detecting the zinc content in the galvanized steel scrap according to claim 2, wherein the calculation method in the step (4) is as follows:
calculating the zinc content of the waste galvanized sheet according to a formula;
in the formula:
m-galvanized coating mass per unit area (double-sided), in grams per square meter (g/M)2)；
m1The mass of the galvanized layer of the sample before dissolution is in grams (g);
m2the mass of the galvanized layer of the sample after dissolution is expressed in grams (g);
a is the area of the sample. The unit is square millimeter (m)m2)。
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| CN202010041601.2A CN111504840A (en) | 2020-01-15 | 2020-01-15 | Method for detecting zinc content of galvanized waste steel |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114318342A (en) * | 2021-12-31 | 2022-04-12 | 马鞍山钢铁股份有限公司 | Corrosion solution for removing galvanized layer of steel plate and method for displaying galvanized steel plate inhibition layer |
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| CN109557084A (en) * | 2019-01-17 | 2019-04-02 | 南通市产品质量监督检验所 | Detection method in such a way that coating iron content identification rope making zinc-coated wire is zinc-plated |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114318342A (en) * | 2021-12-31 | 2022-04-12 | 马鞍山钢铁股份有限公司 | Corrosion solution for removing galvanized layer of steel plate and method for displaying galvanized steel plate inhibition layer |
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