阅读说明：本技术 一种生极板游离铅测试方法 (Free lead testing method for green plate ) 是由 茆黎明 陈战营 胡国柱 于 2020-06-17 设计创作，主要内容包括：本发明涉及电池生产技术领域,公开了一种生极板游离铅测试方法,包括称取样品并研细；取适量碘化钾与样品混合,并加入一定浓度的乙酸铵加热煮沸,搅拌过滤；用1%乙酸铵洗液对搅拌过滤后的溶液洗涤多次,并弃去过滤液与洗涤液,得到沉淀A；在沉淀A中加入1+4硝酸并加热溶解,过滤后再次加入1+4硝酸洗涤2次,用水洗涤8次并稀释摇匀定容至总体积为V<Sub>2</Sub>的试液B；从总体积V<Sub>2</Sub>的试液B中吸取体积为V<Sub>1</Sub>的试液B,并加入20%乙酸铵、20%乌洛托品以及二甲酚橙指示剂,用0.01M EDTA溶液滴至黄色,记录所用毫升数V；测定Pb在原样品中的含量。与现有技术相比,本发明在生极板样品中加入乙酸铵的同时添加碘化钾,充分溶解Pb<Sub>3</Sub>O<Sub>4</Sub>,客观反应游离铅的实际结果。(The invention relates to the technical field of battery production and discloses a method for testing free lead of a green plate, which comprises the steps of weighing a sample and grinding the sample; mixing a proper amount of potassium iodide with a sample, adding ammonium acetate with a certain concentration, heating to boil, stirring and filtering; washing the stirred and filtered solution for multiple times by using 1% ammonium acetate washing liquor, and removing a filtrate and washing liquor to obtain a precipitate A; adding 1+4 nitric acid into the precipitate A, heating for dissolving, filtering, adding 1+4 nitric acid again for washing for 2 times, washing with water for 8 times, diluting, shaking to constant volume 2 The test solution B of (1); from the total volume V 2 The volume of the sample solution B to be aspirated is V 1 Adding 20% ammonium acetate, 20% urotropine and xylenol orange indicator into the test solution B, dripping 0.01M EDTA solution into the mixture to be yellow, and recording the number V of milliliters; and (4) determining the content of Pb in the original sample. Compared with the prior art, the method adds the potassium iodide while adding the ammonium acetate into the sample of the green plate, and fully dissolves the Pb 3 O 4 The actual results of free lead were objectively reflected.)

1. A free lead testing method for a green plate is characterized by comprising the following steps:

s1: weighing a sample from the green plate and grinding the sample, wherein the mass of the sample is expressed by m;

s2: mixing a proper amount of potassium iodide with the sample, adding ammonium acetate with a certain concentration, heating to boil, stirring and filtering;

s3: washing the solution stirred and filtered in the S2 for multiple times by using 1% ammonium acetate washing liquor, and discarding a filtrate and a washing liquor to obtain a precipitate A;

s4: adding 1+4 nitric acid into the precipitate A in the S3, heating for dissolving, filtering, adding 1+4 nitric acid again for washing for 2 times, washing for 8 times with water, diluting, shaking up and fixing the volume to the total volume V₂The test solution B of (1);

s5: from the total volume V₂The volume of the sample solution B to be aspirated is V₁Adding 20% of ammonium acetate, 20% of urotropine and a xylenol orange indicator into the test solution B, dripping 0.01M EDTA solution into the test solution B to be yellow, and recording the number V of milliliters;

s6: determining the content of Pb in the original sample:

wherein C is the molar concentration of EDTA (ethylene diamine tetraacetic acid), and the unit mol/L;

v is the number of milliliters of EDTA solution consumed, in mL;

V₁the volume of the sample solution is expressed in mL;

V₂the unit is mL which is the numerical value of the total volume of the test solution B;

m is the sample weight in g;

0.2072 is the millimolar mass of lead, g/mmol.

2. The green plate free lead test method of claim 1, wherein the mass ratio of the green plate sample to the potassium iodide is 1: 0.1 to 0.4.

3. The green plate free lead test method of claim 1, wherein the concentration of ammonium acetate in S2 is 25%.

4. The green plate free lead test method of claim 1, wherein the heating and boiling time in the S2 is 30 min.

Technical Field

The invention relates to the technical field of battery production, in particular to a method for testing free lead of a green plate.

Background

The lead-acid storage battery is used as a battery with wide application, the polar plate is the heart of the lead-acid storage battery and plays a decisive role in the performance of the battery, and the main components of the polar plate are PbO and PbCO with different proportions₃，PbSO₄，Pb₃O₄，Pb。

The quality of the polar plate is mainly controlled by the following indexes: strength, free lead (the above-mentioned Pb), and moisture. Free lead is useless lead, and too high a lead affects the performance of the plate and wastes the cost of the battery.

The normal determination method of free lead is to add the sample into ammonium acetate solution, heat and boil, and dissolve PbO and PbCO₃，PbSO₄，Pb₃O₄And then filtering, adding nitric acid into the residual insoluble Pb for dissolving, then taking ammonium acetate and urotropine as buffering agents and xylenol orange as indicators, titrating the end point by using EDTA solution, and determining the content of free lead, wherein the content of Pb percent is less than or equal to 5 percent in the current standard, but the Pb percent often exceeds the standard and sometimes reaches 7 percent, and repeated experiments show that the method has certain defects. I.e. ammonium acetate only partially dissolves Pb₃O₄And also 1/3 Pb₃O₄Remaining in the form of lead dioxide can have an effect on the test results. And Pb₃O₄The influence on the result depends on Pb in the polar plate₃O₄The addition ratio of (A) to (B).

Disclosure of Invention

The purpose of the invention is as follows: aiming at the problems in the prior art, the invention provides a method for testing free lead of a green plate, which is characterized in that ammonium acetate is added into a sample, and a potassium iodide reagent is added at the same time, so that Pb is fully dissolved₃O₄Thus objectively reflecting the actual results of free lead.

The technical scheme is as follows: the invention provides a free lead testing method for a green plate, which comprises the following steps:

s1: weighing a sample from the green plate and grinding the sample, wherein the mass of the sample is expressed by m;

s2: mixing a proper amount of potassium iodide with the sample, adding ammonium acetate with a certain concentration, heating to boil, stirring and filtering;

s3: washing the solution stirred and filtered in the S2 for multiple times by using 1% ammonium acetate washing liquor, and discarding a filtrate and a washing liquor to obtain a precipitate A;

s4: adding 1+4 nitric acid into the precipitate A in the S3, heating for dissolving, filtering, adding 1+4 nitric acid again for washing for 2 times, washing for 8 times with water, diluting, shaking up and fixing the volume to the total volume V₂The test solution B of (1);

s5: from the total volume V₂The volume of the sample solution B to be aspirated is V₁Adding 20% of ammonium acetate, 20% of urotropine and a xylenol orange indicator into the test solution B, dripping 0.01M EDTA solution into the test solution B to be yellow, and recording the number V of milliliters;

s6: determining the content of Pb in the original sample:

wherein C is the molar concentration of EDTA (ethylene diamine tetraacetic acid), and the unit mol/L;

v is the number of milliliters of EDTA solution consumed, in mL;

V₁the volume of the sample solution is expressed in mL;

V₂the unit is mL which is the numerical value of the total volume of the test solution B;

m is the sample weight in g;

0.2072 is the millimolar mass of lead, g/mmol.

Further, the mass ratio of the green plate sample to the potassium iodide is 1: 0.1 to 0.4.

Further, the concentration of ammonium acetate in S2 was 25%.

Further, the heating and boiling time period in S2 is 30 min.

Has the advantages that:

1. when the invention is used for testing free lead of the green plate, ammonium acetate is added into a sample, and a potassium iodide reagent is added at the same time, so that Pb is fully dissolved₃O₄And solves the problem of Pb in the free lead testing process in the background technology₃O₄Fails to be fully dissolved to generate PbO₂Defects that affect the free lead results.

2. The mass ratio of the sample to the potassium iodide is 1: can reach the Pb dissolution at 0.1₃O₄The purpose of (1). And the mass ratio of the sample to the potassium iodide is 1: can fully dissolve Pb at 0.4₃O₄The purpose of (1) is that too much addition results in waste, and too little addition does not result in dissolving Pb₃O₄Therefore, the mass ratio of the sampled sample to the added potassium iodide is controlled to be 1: between 0.1 and 04, the good dissolving effect can be achieved.

Detailed Description

The present invention will be described in detail with reference to specific examples.

The invention mainly aims to solve the problem that the ammonium acetate can only partially dissolve Pb in the background technology₃O₄And also 1/3 Pb₃O₄The lead dioxide is retained in the form of lead dioxide, which can affect the test result and the like, so that the free lead test result is inaccurate. The invention discloses a free lead testing method for a green plate, which comprises the following steps:

s1: weighing a sample from the green plate and grinding the sample, wherein the mass of the sample is expressed by m;

s2: mixing a proper amount of potassium iodide with a sample, wherein the mass ratio of the green plate sample to the potassium iodide is 1: 0.1-0.4, adding 25% ammonium acetate, heating and boiling for 30min, stirring and filtering;

s3: washing the solution stirred and filtered in the step S2 for multiple times by using 1% ammonium acetate washing liquor, and discarding the filtrate and washing liquor to obtain a precipitate A;

s4: adding 1+4 nitric acid into precipitate A in S3, heating for dissolving, filtering, and washing with 1+4 nitric acidWashing for 2 times, washing with water for 8 times, diluting, shaking to constant volume₂The test solution B of (1);

s5: from the total volume V₂The volume of the sample solution B to be aspirated is V₁Adding 20% ammonium acetate, 20% urotropine and xylenol orange indicator into the test solution B, dripping 0.01M EDTA solution into the mixture to be yellow, and recording the number V of milliliters;

s6: determining the content of Pb in the original sample:

wherein C is the molar concentration of EDTA (ethylene diamine tetraacetic acid), and the unit mol/L;

v is the number of milliliters of EDTA solution consumed, in mL;

V₁the volume of the sample solution is expressed in mL;

V₂the unit is mL which is the numerical value of the total volume of the test solution B;

m is the sample weight in g;

0.2072 is the millimolar mass of lead, g/mmol.

The present invention will be described below with reference to specific examples.