阅读说明：本技术 一种铝电解槽废阴极底部炭块元素含量定量测定方法 (Quantitative determination method for element content of carbon block at bottom of waste cathode of aluminum electrolytic cell ) 是由 白万里 寇帆 张莹莹 张元克 马慧侠 刘静 彭展 于 2019-10-18 设计创作，主要内容包括：本发明公开了一种铝电解槽废阴极底部炭块元素含量定量测定方法,采用多种标样配制出和大修渣废阴极底部炭块组成相似的系列标准样品,采用压片法制样,X射线荧光光谱法(XRF法)定量测定废阴极及其回收物料中氟、铝、钠、硅、铁、钾、钙、镁的元素含量。本发明主要应用于废阴极无害资源回收及利用中元素定量测定,本方法解决了铝电解槽废阴极元素成分测定误差极大、影响物料加入量、药剂添加量、温度控制等问题,可实现废阴极及其回收物中元素含量的精确测定,进而增强废阴极无害资源化中的过程控制。(The invention discloses a quantitative determination method for the element content of carbon blocks at the bottom of a waste cathode of an aluminum electrolytic cell, which adopts a plurality of standard samples to prepare a series of standard samples similar to the carbon blocks at the bottom of a overhaul slag waste cathode, adopts a tabletting method to prepare samples, and adopts an X-ray fluorescence spectrometry (XRF method) to quantitatively determine the element content of fluorine, aluminum, sodium, silicon, iron, potassium, calcium and magnesium in the waste cathode and recovered materials thereof. The method is mainly applied to the quantitative determination of elements in the recovery and utilization of the waste cathode harmless resources, solves the problems that the determination error of the waste cathode element components of the aluminum electrolytic cell is extremely large, the material addition amount, the agent addition amount, the temperature control and the like are influenced, can realize the accurate determination of the element content in the waste cathode and the recovered materials thereof, and further enhances the process control in the waste cathode harmless resource utilization.)

1. A quantitative determination method for the element content of a carbon block at the bottom of a waste cathode of an aluminum electrolysis cell is characterized by comprising the following steps:

(1) preparing a series of standard samples similar to the components of the waste cathode by using an anthracite standard sample, a high-purity graphite sample, sodium fluoride and an aluminum electrolyte standard sample, wherein the prepared standard samples have certain gradients of elements, wherein the range of fluorine elements is 2-32%, the range of aluminum elements is 1-11%, and the range of sodium elements is 1.5-17%;

(2) preparing a synthesized series of standard samples, adding a solid binder or a liquid grinding aid, preparing samples by a grinding and tabletting method, and preparing a working curve on an X-ray fluorescence spectrometer;

(3) correcting the working curve;

(4) and grinding, tabletting and preparing a sample of the waste cathode to be detected in the same way as the standard sample is prepared, and then measuring the sample by using an X-ray fluorescence spectrometer.

2. The method for quantitatively determining the element content of the carbon block at the bottom of the waste cathode of the aluminum electrolytic cell as claimed in claim 1, wherein in the step (2), the binder is one or a mixture of stearic acid, boric acid, starch, methyl cellulose, microcrystalline cellulose and polyethylene powder, and the ratio of the binder to the sample is 1:10-1: 2; the liquid grinding aid is one or more of absolute ethyl alcohol, glycerol, acetone and propylene glycol, and the adding amount of the grinding aid is 0.5mL-1.5 mL.

3. The method for quantitatively determining the element content in the carbon block at the bottom of the waste cathode of the aluminum electrolytic cell as claimed in claim 1 or 2, wherein in the step (2), the prepared standard sample is ground in a material pot for 20s to 120s, and is subjected to bottoming by using boric acid on a tablet press or direct tabletting, and the pressure is kept for 30s by using 30t of pressure, so that a sample tablet with a smooth surface and no boric acid inclusion is prepared.

4. The method for quantitatively determining the element content in the carbon block at the bottom of the waste cathode of the aluminum electrolytic cell as claimed in claim 1 or 2, wherein in the step (4), the waste cathode carbon block is ground to be sieved by 150 μm and then is subjected to sample preparation by a grinding and tabletting method.

5. The method for quantitatively determining the element content of the carbon block at the bottom of the waste cathode of the overhaul of the aluminum electrolytic cell according to the claim 1 or 2, wherein the working curve correction method can adopt an empirical alpha coefficient method or an FP method.

6. The method for quantitatively determining the element content of the carbon block at the bottom of the waste cathode of the aluminum electrolytic cell as claimed in claim 1 or 2, wherein the determination element categories comprise: fluorine, aluminum, sodium, silicon, iron, potassium, calcium and magnesium.

7. The method for quantitatively determining the element content of the carbon block at the bottom of the waste cathode of the aluminum electrolytic cell as recited in claim 1 or 2, wherein in the step (1), not less than 15 standard samples are prepared.

Technical Field

The invention belongs to the field of analysis and detection in recycling of solid waste resources in the aluminum industry, and particularly relates to a quantitative determination method for the element content of a carbon block at the bottom of a waste cathode in overhaul of an aluminum electrolytic cell.

Background

The aluminum industry in China develops rapidly, and plays an important role in the world aluminum industry, and the yield of electrolytic aluminum in 2018 is 3850 ten thousand tons, which accounts for more than 50% of the global yield of the electrolytic aluminum. The aluminum electrolytic cell in the electrolytic aluminum production is the most central equipment for the original aluminum smelting, the service life of the electrolytic cell in China is only 3-5 years, then the electrolytic cell is overhauled for subsequent original aluminum production, the electrolytic cell waste removed in the overhaul process is overhaul slag, the waste cathode bottom carbon block belongs to the main category of the overhaul slag, and the substances are products of the electrolytic cell bottom cathode carbon block impregnated by electrolyte. The contents of fluorine, aluminum and sodium in the carbon block at the bottom of the waste cathode are greatly increased, and the element types and the content characteristics are the characteristics of electrolyte and cathode carbon. It is calculated that about 15kg of waste cathode bottom carbon blocks are generated for one ton of aluminum, 58 ten thousand tons of waste cathode bottom carbon blocks are generated in 2018, and the accumulated waste cathode bottom carbon blocks in China are more than 500 thousand tons. The waste cathode is rich in a large amount of harmful substances, belongs to dangerous waste, and belongs to the category of overhaul residues which are recorded in national records of dangerous waste, have the serial number of HW48 and are characterized by T (toxicity) and need to be recycled.

The elemental composition of the waste cathode raw material before recovery and the elemental composition of the material after recovery in the harmless resource recovery work of the carbon block at the bottom of the waste cathode can clearly reflect the effect of the recovery technology, so the elemental composition of the waste cathode is an important index and has guiding effect on various data such as the addition amount of materials, the addition amount of medicaments, the temperature and the like in the process, and the index has important significance for scientifically and reasonably evaluating the recovery effect; although there are many documents and patents on recycling of harmless resources of relevant waste cathodes, and the technical standard work of harmless recycling of relevant waste cathodes is also in process, because the components of the waste cathodes and recycled materials of an electrolytic cell are extremely complex, no method for analyzing the components of the waste cathodes exists in the prior art, only part of research documents of harmless treatment of the waste cathodes refers to a method for measuring the element content of carbon blocks at the bottom of the waste cathodes, but the details of measurement are not detailed, so that the measurement of the element content of the waste cathodes is almost in a blank state, which brings many problems and inconvenience to the recycling work of the relevant waste cathode resources, and simultaneously causes the assessment work of the relevant technology of the recycling of the waste cathode resources to lack scientificity and rigidness.

Disclosure of Invention

In order to solve the problems that the measurement error of the carbon block at the bottom of the waste cathode and the related material elements thereof is extremely large and the subsequent harmless treatment process of the waste cathode is influenced, the invention provides a method for quantitatively measuring the carbon block at the bottom of the waste cathode and the related material thereof by using an X-ray fluorescence spectrometry.

The purpose of the invention is realized by the following technical steps:

a quantitative determination method for the element content of a carbon block at the bottom of a waste cathode of an aluminum electrolysis cell is characterized by comprising the following steps:

(1) preparing a series of standard samples similar to the components of the waste cathode by using an anthracite standard sample, a high-purity graphite sample, sodium fluoride and an aluminum electrolyte standard sample, wherein the prepared standard samples have certain gradients of elements, wherein the range of fluorine elements is 2-32%, the range of aluminum elements is 1-11%, and the range of sodium elements is 1.5-17%;

(2) preparing a synthesized series of standard samples, adding a solid binder or a liquid grinding aid, preparing samples by a grinding and tabletting method, and preparing a working curve on an X-ray fluorescence spectrometer;

(3) correcting the working curve;

(4) and grinding, tabletting and preparing a sample of the waste cathode to be detected in the same way as the standard sample is prepared, and then measuring the sample by using an X-ray fluorescence spectrometer.

The method for quantitatively determining the element content of the carbon block at the bottom of the waste cathode of the aluminum electrolytic cell is characterized in that in the step (2), the binder is one or a mixture of stearic acid, boric acid, starch, methyl cellulose, microcrystalline cellulose and polyethylene powder, and the proportion of the binder to the sample is 1:10-1: 2; the liquid grinding aid is one or more of absolute ethyl alcohol, glycerol, acetone and propylene glycol, and the adding amount of the grinding aid is 0.5mL-1.5 mL.

According to the method for quantitatively determining the element content of the carbon block at the bottom of the waste cathode of the aluminum electrolytic cell, the prepared standard sample is ground in a material bowl for 20-120 s in the step (2), a tablet press is used for edging and bottoming by boric acid or directly tabletting, and the pressure is maintained for 30s at 30t, so that a sample tablet with a smooth surface and no boric acid inclusion is prepared.

The method for quantitatively measuring the element content of the carbon block at the bottom of the waste cathode of the aluminum electrolytic cell is characterized in that in the step (4), the waste cathode carbon block is ground to be sieved by 150 mu m, and then a grinding and tabletting method is adopted for sample preparation.

The method for quantitatively determining the element content of the carbon block at the bottom of the waste cathode of the aluminum electrolytic cell is characterized in that the working curve correction method can adopt an empirical alpha coefficient method or an FP method.

The method for quantitatively determining the element content of the carbon block at the bottom of the waste cathode of the aluminum electrolytic cell is characterized in that the determination element types comprise: fluorine, aluminum, sodium, silicon, iron, potassium, calcium and magnesium.

The method for quantitatively determining the element content of the carbon block at the bottom of the waste cathode of the aluminum electrolytic cell is characterized in that not less than 15 standard samples are prepared in the step (1).

The invention relates to a method for quantitatively analyzing a waste cathode bottom carbon block by X-ray fluorescence spectrometry (XRF), which accurately measures the element content in a waste cathode and related materials thereof by preparing a standard sample with similar components and structures to the waste cathode and preparing a working curve by preparing the standard sample. The method has the advantages that the accurate measurement of the carbon block at the bottom of the waste cathode and the useful elements in the recycled materials thereof has important significance for the harmless and recycling treatment process of the waste cathode, the accurate measurement of the carbon block at the bottom of the primary raw material waste cathode is more favorable for the accurate measurement and the accurate calculation and the putting of materials such as acid, alkali, a flotation agent and the like in the harmless and recycling treatment process, the waste and the environmental pollution are avoided, the corresponding economic benefit is generated, the flow control is enhanced for the accurate measurement of the process materials, meanwhile, the method has more positive effect on the scientific evaluation of the recycling treatment effect of the carbon block at the bottom of the waste cathode, the phenomenon of the waste of immature waste cathode recycling technology is avoided, and a new technical guarantee is provided.

Detailed Description

The method for quantitatively measuring the element content of the carbon block at the bottom of the overhaul slag waste cathode of the aluminum electrolytic cell adopts a plurality of standard samples to prepare a series of standard samples similar to the carbon block at the bottom of the overhaul slag waste cathode, and adopts a tabletting method to prepare samples and an X-ray fluorescence spectrometry (XRF method) to quantitatively measure the element content of fluorine, aluminum, sodium, silicon, iron, potassium, calcium and magnesium in the carbon block at the bottom of the waste cathode and related materials. The method comprises the following steps:

(1) preparing a standard sample: preparing a series of standard samples similar to the components of the waste cathode bottom carbon block and the recycled materials thereof by using an anthracite standard sample, a high-purity graphite sample, sodium fluoride and an aluminum electrolyte standard sample; the number of prepared standard samples is not less than 15, wherein the range of fluorine element is 2-32%, the range of aluminum element is 1-11%, and the range of sodium element is 1.5-17%.

(2) Adding a suitable solid binder or liquid grinding aid into the prepared standard sample: the binder can be stearic acid, boric acid, starch, methylcellulose, microcrystalline cellulose, polyethylene powder and a mixed binder in proportion, wherein the proportion of the binder to the sample is 1:10-1: 2; the liquid grinding aid can be, but is not limited to, the following: anhydrous alcohol, glycerin, acetone, propylene glycol, etc. and the grinding assistant is added in 10-30 drops.

(2) Grinding and tabletting: weighing 10g of prepared standard sample, adding 1g of stearic acid or boric acid, grinding in a tungsten carbide material bowl for 30-60 s, directly tabletting the ground sample in a tablet press or tabletting by a chemical pure boric acid bottoming mode, wherein the tabletting pressure is 30t, and the pressure maintaining time is 30 s.

(3) Manufacturing a tool set curve: and (4) making a working curve of the prepared standard sample on an X-ray fluorescence spectrometer.

(4) And (3) correcting a working curve: preferably, an empirical alpha coefficient method is used for correction, an FP method (basic parameter method) can also be used for correction, the corrected working curve is verified by applying more than 3 sample wafers without the working curve, the accuracy of F element of the unknown sample is controlled within +/-0.5%, Al element is controlled within +/-0.4%, Na element is controlled within +/-0.4%, and sodium, silicon (in the form of silicon dioxide), iron (in the form of ferric oxide), potassium, calcium, magnesium and the like are controlled within +/-0.3%.

(5) Grinding, tabletting and sample preparation are carried out on the carbon block at the bottom of the waste cathode to be detected and related materials by a 150-micron sieve in the same steps (2) and (3) as the preparation of the calibration sample, temporary replacement of a binder, an auxiliary grinding agent or other conditions is not needed in the midway, the sample preparation consistency is kept, and sample determination is carried out by an X-ray fluorescence spectrometer after sample preparation.