CN109855988B - Method for measuring falling strength of lead smelting slag charging granules/pellets - Google Patents
Method for measuring falling strength of lead smelting slag charging granules/pellets Download PDFInfo
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Abstract
The invention relates to a method for measuring the falling strength of lead smelting slag charging granules/pellets, which comprises the following steps: in the same batch of products, a random sampling or system sampling mode is adopted to obtain a sample to be inspected; carrying out a free fall experiment on the selected test samples to obtain the total mass of fragments of each test sample; calculating the drop strength evaluation index of the same batch of products according to the total mass of the obtained fragments
The method can accurately, efficiently, simply and objectively evaluate the falling strength and the production quality of lead smelting charging materials of different batches.
Description
Technical Field
The invention belongs to the field of nonferrous metallurgy, and particularly relates to a method for measuring the falling strength of lead smelting slag charging granules/pellets.
How to measure and evaluate the falling strength of the lead smelting furnace-entering granules and pellets. The method improved by the patent can be used for accurately, efficiently, concisely and objectively evaluating the falling strength of the aggregates and the pellets. The method is mainly applied to the field of nonferrous metallurgy, and can also be applied to the measurement of the falling strength of products such as ironmaking pellets, sinter or coal.
Background
The prior treatment methods of smelting lead and feeding into a furnace comprise roller/disc ball making, pressure ball making and the like. The furnace charge materials manufactured by various methods have very large property difference, especially the falling strength, and some products are not easy to break and some products are easy to break; some raw materials have high water content and even have fluidity; some raw materials contain very little water and are desertified by light touch. However, there is currently no very suitable method for evaluating the drop strength of lead-like charges.
In actual production, the evaluation of the falling strength of the existing factory is not taken into consideration, and the mode of regulating and controlling smelting parameters and adding auxiliary materials is emphasized to ensure the smooth production, but the additional energy consumption caused by the shortage of the properties of the raw materials is not taken into consideration. The falling strength is an important property of the lead smelting raw material, and has important influence on smooth production, energy consumption and pollution discharge. However, the existing methods can not completely meet the evaluation of the falling strength of lead smelting raw materials, and the methods mainly relate to coal and iron-smelting green pellets and are direct and simple. The reason is that the manufacturing process of the products such as coal, iron-making green ball and the like is mature, the quality is stable, and a proper result can be obtained by adopting a plurality of simple methods. The quality of the lead smelting charging materials is greatly dispersed due to the influence of factors such as moisture, pressure, components and the like, and the existing method cannot be used for accurately evaluating, for example, in the same batch of samples, some charging granules are completely crushed after 1 time of falling, and some charging granules are completely crushed after 2 times of falling, and the falling strength of the charging granules is the same by the existing method for evaluating coal or green pellets. In practice they are different, the second one being likely to meet the furnace feed requirements, but the first one being substantially unsatisfactory. For another example, an incoming pellet does not break down substantially, but loses < 1% of its mass with each drop; while the other was only dropped in half (2 pieces were larger than the statistical size) several times, but no flaking occurred. The first type will have a high drop strength with the old method, but in practice the second type will have a lower strength with the lead slag. For the raw materials of the same batch, some raw materials are not crushed at all, and some raw materials are easy to crush; directly averaging one batch does not allow accurate evaluation of the batch. Therefore, it is necessary to design a new method for fitting the requirement of lead smelting to charge materials to objectively and accurately evaluate the dropping strength of the lead slag to the charge materials.
In industry, the lead smelting furnace charge needs to have certain compressive strength and drop strength. The concrete embodiment is as follows: the dust is not scattered due to pressure during placement and storage, and is not evaporated to drop dust; the material is not broken when being subjected to light collision in the processes of carrying and loading; after entering the furnace, the material is not scattered due to the high temperature of the furnace mouth; slightly broken after falling to the bottom of the furnace, but can be kept for a period of time without loosening; low water content, but moderate compressive strength.
What is a suitable drop strength evaluation method designed for such a complicated requirement? First, the situation of very high strength and almost no strength is considered. Secondly, it is desirable to be able to objectively assess what grade a sample is in for different crushing states. Still further, it is desirable to be easily applicable, and particularly applicable without the use of auxiliary tools, to meet certain emergency situations. The core is how to subdivide the degree of fragmentation and characterize it mathematically, which can be improved based on the industry standards that are currently mature.
Disclosure of Invention
The invention aims to provide a method for measuring the falling strength of shot materials/pellets of lead smelting slag, which solves the defects in the prior art.
In order to achieve the purpose, the invention adopts the technical scheme that:
the invention provides a method for measuring the falling strength of lead smelting slag charging granules/pellets, which comprises the following steps:
s1, selecting a test sample: in the same batch of products, a random sampling or system sampling mode is adopted to obtain a sample to be inspected;
s2, carrying out free fall experiment on the test sample selected in the S1 to obtain the total mass m of the fragments of each test sampleL；
S3, calculating the evaluation index of the falling strength of the same batch of products according to the total mass of the fragments obtained in S2
Preferably, in step S2, the specific method for performing the free fall test on the selected test sample is as follows:
s21, dropping the sample from the 2.5m calibration position, impacting the sample with a bottom plate to obtain a plurality of first fragments, and entering S22;
s22, selecting the first fragments with mass more than 20% x m from all the first fragments obtained in S210After the first chip of (2.5 m) from the nominal positionThen, the second fragments are impacted with the bottom plate to obtain a plurality of second fragments, and S23 is carried out;
s23, selecting the second fragments with mass more than 20% x m from all the second fragments obtained in S220Then the second fragments fall from the 2.5m calibration position, and collide with the bottom plate to obtain a plurality of third fragments, and the step S24 is carried out;
s24, calculating the mass selected in S22 to be more than 20% multiplied by m0The mass of the first fragment of (S23) is more than 20% x m0And the mass obtained in S23 is more than 20% x m0Total mass m of the third fragment of (2)LAnd the total number of experiments, x, was recorded as 3.
Preferably, the ground falling point is paved with a ceramic plate or a steel plate, wherein the thickness of the ceramic plate or the steel plate is not less than 1cm, and the hardness is not less than 56 HRC.
Preferably, if the number of experiments is less than three, the mass of the obtained fragments is less than 20% x m0Then the total number of times x the experiment was performed was recorded and the mass was calculated to be less than 20% x m0And more than 10% x m0Total mass m of all fragments ofL。
Preferably, in step S3, the formula for calculating the evaluation index of the drop strength of the same batch of products is:
wherein Q isLX-iRefers to the drop strength of the ith test sample; n represents the total number of samples used for testing.
Preferably, QLXThe calculation formula of (2):
wherein n represents the upper limit of the falling strength, and an integral value of 1-4 is taken according to the frangibility degree; j is mass>20％m0Total number of fragments of, and j<5, when there is no mass after the end of the test>20％m0Is considered to be infiniteClose to 0, when j is 1; m is0Is the original mass of the sample.
Compared with the prior art, the invention has the beneficial effects that:
the method for measuring the falling strength of the shot/pellet of the lead smelting slag has the advantages that the falling strength of the raw material is not measured through mass loss or volume loss through machinery any more, and more importantly, the falling strength of the raw material is objectively and scientifically evaluated based on factors such as the number of times of complete crushing, the quality and quantity of the residual fragments meeting the requirements, the dispersion of the falling strength of batch samples and the like. Suitable samples include: extremely fragile, non-fragile, substantially unbroken, etc., while also being applicable to samples which are fragile but differ in their fragmentation pattern by factors such as the number of times and number of fragments, substantially covering all sample types.
Further, the total mass m after 3 drops of a single sample is required to be taken in S2LThe main reason is that the band can be brought into mLObtaining Q from the formulaLXTo facilitate subsequent calculations.
Further, it is required to obtain in S3
The parameter is the falling strength of a batch of material and is the Q of a single sample obtained by random samplingLXAnd averaging to obtain the average value. This is because of the Q of a single sampleLXCannot evaluate a batch of samples, and therefore needs to be evaluated by finding
To be implemented.
In conclusion, the method can accurately, efficiently, simply and objectively evaluate the falling strength and the production quality of lead smelting charging materials of different batches.
Drawings
FIG. 1 is a schematic view of a testing apparatus according to the present invention;
fig. 2 is a schematic of a sample.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
The method for measuring the falling strength of the lead smelting slag charging granules/pellets extracts the advantages of other methods, performs new design and demonstration according to the characteristics and requirements of lead smelting charging materials, and can objectively and accurately evaluate the materials. The method comprises the following steps:
s1, selecting a test sample:
when the products are the same batch of products, acquiring the inspection samples in a random sampling or system sampling mode, wherein when the number of the products in the same batch is less than or equal to 3t, the number of the test samples is 12; when the number of the products in the same batch is more than 3t, increasing and selecting according to the number of 2 particles/per.t;
when a macroscopic evaluation is performed for different batches and with a total <3t, disordered sample, there are two approaches: first, sample batches can be sorted and sampled according to the sampling method described in this article. Secondly, if the batches cannot be clearly divided, the materials are regarded as a whole, and the random sampling method is adopted to double-select the samples.
The diameter of the test sample is 10 mm-35 mm;
s2, carrying out a free fall experiment on the test sample selected in the S1, wherein the fall distance is 2.5 m; a ceramic plate or a steel plate is laid on the ground falling point, wherein the thickness of the ceramic plate or the steel plate is not less than 1cm, and the hardness is not less than 56HRC, as shown in figure 1;
specifically, the method comprises the following steps:
s21, dropping the sample from the 2.5m calibration position, impacting the sample with a bottom plate to obtain a plurality of first fragments, and entering S22;
s22, selecting the first fragments with mass more than 20% x m from all the first fragments obtained in S210Then falls from the 2.5m calibration position, and collides with the bottom plate to obtain a plurality of second fragments, and the step S23 is carried out;
s23, selecting the second fragments with mass more than 20% x m from all the second fragments obtained in S220Then the second fragments fall from the 2.5m calibration position, and collide with the bottom plate to obtain a plurality of third fragments, and the step S24 is carried out;
s24, calculating the mass selected in S22 to be more than 20% multiplied by m0The mass of the first fragment of (S23) is more than 20% x m0And the mass obtained in S23 is more than 20% x m0Total mass m of the third fragment of (2)LAnd the total number of experiments, x, was recorded as 3.
If the experiment times are less than three times, the mass of the obtained fragments is less than 20% multiplied by m0Then the total number of times x the experiment was performed was recorded and the mass was calculated to be less than 20% x m0And more than 10% x m0Total mass m of all fragments ofL。
S3, calculating the evaluation index of the falling strength of the same batch of products according to the total mass of the fragments obtained in S2
Specifically, the method comprises the following steps:
formula for the drop strength of each test sample:
calculation formula of dispersion of falling intensity of each test sample:
evaluation index of drop strength of same batch of products
The calculation formula of (2):
wherein Q isLXRefers to the drop strength of any one sample; qLX-iRefers to the drop strength of the ith test sample; n represents the total number of samples used for testing; n represents drop strengthThe upper limit is an integral value of 1-4 according to the frangibility degree; j is mass>20％m0Total number of fragments of, and j<5, if there is no quality after the end of the test>20％m0If the fragment of (a) is j is infinitely close to 0, taking j to be 1; m is0Is the original mass of the sample.
Wherein the falling strength QLXThe larger the size, the less likely the charged particles will break;
dispersion VLXThe smaller; indicating that the quality of the same batch of product is relatively uniform.
The calculation formula of the evaluation index of the falling strength has certain similarity with the related industry standard. The difference is that the formula can be negative, primarily for extremely fragile samples, subdividing their degree of breakage. The related national and industrial standards are as follows: a method for measuring the dropping strength of MT/T925-2004 industrial briquettes, a method for measuring the dropping strength of YB/T4606-2017 sinter ore, a method for measuring the drum strength of YB T5166-sinter ore and pellet ore, a method for measuring the dropping strength of coke (GB/T4511.2-1999), and a method for measuring the dropping strength of GB/T15459-2006 coal.
A batch of 5t of cylindrical granules with the nominal diameter of 13cm is produced by a certain lead refinery by adopting a pressing process, and the falling strength of the granules and the production quality uniformity of the granules need to be known. After preliminary trial, taking n to 4, namely the maximum drop strength of the batch of products is 4. There were 7 samples of this batch, each at 3t below, the species being classified according to water content: 0%, 1%, 2%, 3%, 4%, 6%, 8%. The test results are shown in table 1.
TABLE 1 sample drop Strength QLXAnd falling strength of the pellets
Test results
The results show that the falling strength of the pellets varies with the water contentThe formation tends to increase first. The water content in the raw materials shows a positive influence on the particle forming and the drop strength. In addition VLXThe trend of (2) shows an inverse trend with the moisture content, indicating that too low a moisture content may affect the uniformity of the product quality, so that QLXThe dispersion increases. Fig. 2 shows the samples after the drop test, some completely crushed, and some substantially intact.
Claims (2)
1. A method for measuring the falling strength of shot materials/pellets of lead smelting slag is characterized by comprising the following steps:
s1, selecting a test sample: in the same batch of products, a random sampling or system sampling mode is adopted to obtain a sample to be inspected;
s2, carrying out free fall experiment on the test sample selected in the S1 to obtain the total mass m of the fragments of each test sampleL；
S3, calculating the evaluation index of the falling strength of the same batch of products according to the total mass of the fragments obtained in S2
In S2, the specific method for performing the free fall experiment on the selected test sample is:
s21, dropping the sample from the 2.5m calibration position, impacting the sample with a bottom plate to obtain a plurality of first fragments, and entering S22;
s22, selecting the first fragments with the mass more than 20% multiplied by m from all the first fragments obtained in S210Then falls from the 2.5m calibration position, and collides with the bottom plate to obtain a plurality of second fragments, and the step S23 is carried out;
s23, selecting the second fragments with the mass more than 20% multiplied by m from all the second fragments obtained in S220Then the second fragments fall from the 2.5m calibration position, and collide with the bottom plate to obtain a plurality of third fragments, and the step S24 is carried out;
s24, calculating the mass selected in S22 to be more than 20 percent multiplied by m0The mass of the first fragment of (S23) is more than 20% x m0And the mass obtained in S23 is more than 20% x m0Total mass m of the third fragment of (2)LAnd recording the total number x of the impacts with the bottom plate as 3;
if the number of times of the experiment is less than three, the mass of the fragments obtained by the last time of the impact with the bottom plate is less than 20% multiplied by m0Then the total number of impacts x with the floor is recorded and the mass is calculated to be less than 20% x m0And more than 10% x m0Total mass m of all fragments ofL；
In step S3, evaluation index of drop strength of products of the same batch
The calculation formula of (2):
wherein Q isLX-iRefers to the drop strength of the ith test sample; n represents the total number of samples used for testing;
QLX-ithe calculation formula of (2):
wherein n represents the upper limit of the falling strength, and an integral value of 1-4 is taken according to the frangibility degree; j is mass>20％m0Total number of fragments of, and j<5, when there is no mass after the end of the test>20％m0If the fragment of (a) is j is infinitely close to 0, taking j to be 1; m is0Is the original mass of the sample; qLXRefers to the drop strength of any one sample;
the ground falling point is laid with a ceramic plate or a steel plate.
2. The method for measuring the falling strength of the shot/pellet of lead smelting slag as claimed in claim 1, wherein the ceramic plate or steel plate has a thickness of 1cm or more and a hardness of 56HRC or more.
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