Method for determining flotation design time based on laboratory closed-circuit flotation test

Abstract

The present invention discloses a method for determining the flotation design time based on laboratory flotation closed-circuit tests, which is determined according to the data obtained in the flotation closed-circuit tests. The data includes the minimum number of test groups required to reach the equilibrium state in the test, the total weight of middlings in a single-group test after reaching the equilibrium state, and the data of the additional water volume in a single-group test after reaching the equilibrium state. The present invention can accurately calculate the flotation design time, so as to achieve a high degree of fitting between the flotation design time and the laboratory closed-circuit flotation test time, make a reasonable evaluation of the flotation time of the existing production process, and can also provide accurate data for the subsequent process design and equipment selection. It is applicable to the process design and flow diagnosis of most metal ore beneficiation processes, and has the characteristics of simple calculation and strong practicability.

Description

Technical Field

[0001] The present invention relates to a method for determining the flotation design time. Background Art

[0002] The flotation method is widely used for the separation of metal minerals, non-metal minerals, chemical raw material minerals, etc.

[0003] In the production of a concentrator, the sum of the flotation times of the rougher operation and each scavenging operation is called the flotation time. The flotation time is an important control parameter in the flotation control process and is closely related to the flotation effect. Each type of ore has its suitable flotation time. If the flotation time is too short, the recovery rate is low; if the flotation time is long, the recovery rate increases, but the concentrate quality decreases. At the same time, more flotation machines are required, which will increase the construction investment and operating energy consumption of the concentrator, resulting in an increase in the beneficiation cost.

[0004] In the existing flotation control process, there are several different ways to determine the flotation time:

[0005] First, when designing the flotation of a concentrator, the total time t0 of rougher and scavenging in the flotation test process is first determined through laboratory open-circuit tests. t0 is the flotation open-circuit test time. Then, referring to the actual flotation time in industrial production of concentrators of the same type, t0 is multiplied by a magnification factor k to determine the final flotation design time of the concentrator, so as to control the flotation process. After consulting the literature, the value of the magnification factor k is an empirical data, and there are few articles reporting on the basis for the selection of the k value. Generally, the k value for foreign concentrators is taken as 2, and the k value for domestic concentrators is generally taken as 1.5.

[0006] Second, the following empirical calculation formula for the flotation time has also been proposed in the prior art:

[0007]

[0008] In the formula, T—the flotation design time, min;

[0009] t0—the flotation time determined by tests, min;

[0010] q0—the aeration rate of the test flotation machine, m 3 / (m 2 ·min);

[0011] q—the aeration rate of the industrial flotation machine, m 3 / (m 2 ·min);

[0012] Δt—the additional flotation time according to production practice, min.

[0013] However, for the above empirical formula, the value-taking methods given in different literatures also vary. Referring to the "Mineral Processing Design Manual", the first edition published by Metallurgical Industry Press of Beijing in July 1988, Δt = 0.5×k×t0, with the unit of min, and generally k = 1.5 - 2. While referring to "Flotation", the first edition published by Metallurgical Industry Press of Beijing in August 2018, Δt = k×t0, with the unit of min, and generally k = 1.5 - 2.

[0014] It can be seen that even under the same test conditions and data, there will be significant differences in the flotation design time obtained by different calculation methods. For example, the flotation design time obtained based on the "Mineral Processing Design Manual" is shorter than that based on "Flotation". The former is likely to result in low recovery rate, while the latter may lead to problems such as low concentrate quality, increased production and investment costs. Summary of the Invention

[0015] The present invention proposes a method for determining the flotation design time based on laboratory flotation closed-circuit tests. The purpose is to provide an accurate flotation design time, avoid problems such as low recovery rate, poor concentrate quality, and excessive investment caused by unreasonable flotation time, and at the same time can be used as reference data for equipment selection and process reconstruction and expansion.

[0016] The technical solution of the present invention is as follows:

[0017] A method for determining the flotation design time based on laboratory flotation closed-circuit tests, where the flotation design time is determined based on the data obtained from the flotation closed-circuit tests. This data includes the minimum number of test groups required to reach the equilibrium state in the test, the total dry weight of the middlings in a single test group after reaching the equilibrium state, and the data of the additional water volume in a single test group after reaching the equilibrium state.

[0018] As a further improvement of the method for determining the flotation design time based on laboratory flotation closed-circuit tests, the calculation formula for the flotation design time is:

[0019]

[0020] where n represents the number of test groups when the laboratory closed-circuit flotation test first reaches the equilibrium state; t0 represents the flotation open-circuit test time, with the unit of min; m z represents the total dry weight of the middlings in a single test group after the flotation closed-circuit test reaches equilibrium, with the unit of g; m0 represents the dry weight of the original ore sample fed into a single test group in the flotation closed-circuit test, with the unit of g; V w represents the additional water volume in a single test group in the closed-circuit test, with the unit of ml; V0 represents the volume of the flotation cell used in the closed-circuit test, with the unit of ml; q0 represents the aeration rate of the test flotation machine, with the unit of m 3 / (m 2· min); q represents the aeration rate of the industrial flotation machine, with the unit of m 3 / (m 2 · min).

[0021] As a further improvement to the method for determining the flotation design time based on the laboratory flotation closed-circuit test: The laboratory flotation closed-circuit test adopts a cyclic flotation method. Each round of flotation produces concentrate, tailings, and middlings, and the middlings are then floated again together with the newly added raw ore in the next round.

[0022] As a further improvement to the method for determining the flotation design time based on the laboratory flotation closed-circuit test: After the flotation closed-circuit test is completed, calculate the yields of the concentrate and tailings and the grade of the tailings. If there exists a smallest possible integer n' that can satisfy the following conditions simultaneously:

[0023] (a) Starting from the n'-th test, the fluctuation range of the combined yield of the concentrate and tailings is less than the preset value;

[0024] (b) Starting from the n'-th test, the fluctuation range of the grade of the tailings is less than the preset value;

[0025] Then take the integer n' as the number of test groups n when the equilibrium state is first reached.

[0026] As a further improvement to the method for determining the flotation design time based on the laboratory flotation closed-circuit test: Each round of the laboratory flotation closed-circuit test includes one roughing, one cleaning, and two scavenging steps, as follows:

[0027] (1) Start the first round of tests, add the raw ore, conduct roughing to obtain roughing concentrate and roughing tailings; conduct cleaning on the roughing concentrate to obtain concentrate and cleaning tailings; conduct the first scavenging on the roughing tailings to obtain scavenging concentrate and scavenging tailings; use the cleaning tailings and scavenging concentrate as the first middlings; conduct the second scavenging on the scavenging tailings to obtain tailings and the second middlings; record the makeup water volume, filter press the concentrate and tailings, weigh them for standby, and uniformly dry, weigh, and assay the grade after the closed-circuit test ends;

[0028] (2) Start the next round of tests, conduct roughing on the newly added raw ore and the first middlings of the previous round together to obtain roughing concentrate and roughing tailings; conduct cleaning on the roughing concentrate to obtain concentrate and cleaning tailings; conduct the first scavenging on the roughing tailings and the second middlings of the previous round together to obtain scavenging concentrate and scavenging tailings; use the cleaning tailings and scavenging concentrate as the first middlings of this round; conduct the second scavenging on the scavenging tailings to obtain tailings and the second middlings of this round; record the makeup water volume, filter press the concentrate and tailings, weigh them for standby, and uniformly dry, weigh, and assay the grade after the closed-circuit test ends;

[0029] (3) Return the first middlings and the second middlings of this round to the flotation process flow, repeat step (2) to conduct the next round of tests; after the weight data of the concentrate and tailings after pressure filtration in each round of flotation are stable, continue to conduct 1 to 2 more rounds of tests, then filter, dry, and weigh the middlings of the last group of tests, and record the weight.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] Through the laboratory closed-circuit flotation test on the ore sample, the present invention obtains the required test data, accurately calculates the flotation design time according to the new correction formula, so as to achieve a high degree of fitting between the flotation design time and the laboratory closed-circuit flotation test time, eliminate the rough error of the empirical algorithm for the flotation design time, make a reasonable evaluation of the flotation time of the existing production process, and can also provide accurate data for the subsequent process flow design and equipment selection, avoiding problems such as low recovery rate, low concentrate quality, and increased production and investment costs caused by too short or too long flotation time. This method is applicable to the design and process diagnosis of most metal ore beneficiation processes, and has the characteristics of simple calculation and strong practicability.

[0032] Furthermore, the equilibrium state is judged by the total yield of the concentrate and tailings and the fluctuation of the tailings grade. When both reach a stable state, it indicates that the middlings in the first group of tests in the closed-circuit flotation test have been completely separated, and the time from the start of the second group of tests in the closed-circuit flotation test to the first reaching the equilibrium state is the time required for the separation of the middlings in the first group. Based on this time, the flotation design time can be preliminarily determined, which can ensure sufficient flotation time, enable effective separation of the middlings, and at the same time avoid the situation of decreased concentrate grade and increased tailings grade.

[0033] On the other hand, the present invention fully considers the differences between the closed-circuit flotation test and on-site production: First, in on-site production, the stability of the liquid level height in the flotation machine mainly depends on continuous feeding, so the pulp concentration is relatively stable, while in the test, it is necessary to continuously add clear water to maintain the liquid level height, resulting in a slow decrease in the pulp concentration; Second, the aeration effect of the test flotation machine is better than that of the production flotation machine, and the flotation rate is higher. In view of the above problems, the present invention further corrects the calculation results according to the data of the water make-up volume and equipment aeration volume in the test, eliminates the influence brought by the above differences, improves the accuracy of the flotation parameters, enhances the flotation effect, and reduces the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic flow diagram of the closed-circuit test. DETAILED DESCRIPTION OF THE INVENTION

[0035] The technical solution of the present invention will be described in detail below with reference to the drawings:

[0036] A method for determining the flotation design time based on laboratory closed-circuit flotation tests, the core of which is to determine the flotation design time based on the data obtained from the laboratory closed-circuit flotation tests. The laboratory closed-circuit flotation tests adopt a cyclic flotation method. In each round of flotation, concentrate, tailings and middlings are produced, and the middlings are then re-flotated together with the newly added raw ore in the next round. The data includes the minimum number of test groups required to reach the equilibrium state in the test, the total weight of the middlings in a single-group test after reaching the equilibrium state, and the data of the additional water volume in a single-group test after reaching the equilibrium state.

[0037] Such as Figure 1 , each round of laboratory closed-circuit flotation tests includes one roughing, one cleaning and two scavenging steps, and the specific steps are as follows:

[0038] (1) Start the first round of tests, add raw ore, conduct roughing to obtain roughing concentrate and roughing tailings; conduct cleaning on the roughing concentrate to obtain concentrate and cleaning tailings; conduct the first scavenging on the roughing tailings to obtain scavenging concentrate and scavenging tailings; use the cleaning tailings and scavenging concentrate as the first middlings; conduct the second scavenging on the scavenging tailings to obtain tailings and the second middlings; record the additional water volume, weigh the concentrate and tailings after pressure filtration for standby, and uniformly dry, weigh and assay the grade after the closed-circuit test is completed.

[0039] In this embodiment, the middling products are collected in a 3L beaker. After the test is completed, all the concentrate and tailings products need to be dried, weighed and assayed. To preliminarily judge whether the test products have reached equilibrium, it is preferred to filter each group of concentrate during the test and weigh the wet weight of the filter cake.

[0040] (2) Start the next round of tests, conduct roughing on the newly added raw ore and the first middlings of the previous round together to obtain roughing concentrate and roughing tailings; conduct cleaning on the roughing concentrate to obtain concentrate and cleaning tailings; conduct the first scavenging on the roughing tailings and the second middlings of the previous round together to obtain scavenging concentrate and scavenging tailings; use the cleaning tailings and scavenging concentrate as the first middlings of this round; conduct the second scavenging on the scavenging tailings to obtain tailings and the second middlings of this round; record the additional water volume, weigh the concentrate and tailings after pressure filtration for standby, and uniformly dry, weigh and assay the grade after the closed-circuit test is completed.

[0041] (3) Return the first and second middlings of this round to the flotation process flow, repeat step (2) to conduct the next round of tests. After the weight data of the concentrate and tailings after pressure filtration in each round of flotation are basically stable, continue to conduct 1-2 more rounds of tests. Filter, dry, weigh and record the weight of the middlings in the last group of tests.

[0042] Generally, 5 - 8 sets of closed - circuit experiments are conducted consecutively. Whether the experiment reaches equilibrium is marked by whether the metal content and yield of the flotation products in the last few sets of experiments are approximately equal. The specific judgment criteria are as follows: After the closed - circuit experiment is completed, all samples are weighed and analyzed, and the yields of the concentrate and tailings and the grade of the tailings are calculated. If there exists a smallest possible integer n' such that the following conditions are simultaneously satisfied:

[0043] (a) Since the n'th experiment, the fluctuation range of the total yield of the concentrate and tailings is less than the preset value;

[0044] (b) Since the n'th experiment, the fluctuation range of the grade of the tailings is less than the preset value;

[0045] Then the integer n' is taken as the number of experimental groups n when the equilibrium state is first reached.

[0046] Since both the original ore and the middlings enter the same set of process equipment for separation, the flotation time of the middlings and the original ore needs to be kept consistent. Compared with the original ore, the target minerals in the middlings are embedded with finer particle sizes, lower degrees of dissociation, and are more closely combined with gangue, making them difficult to separate. Therefore, the flotation time required for the complete separation of the middlings is longer than that of the original ore. If the flotation time is insufficient and the middlings are not effectively separated, the amount of middlings will continue to increase without reaching equilibrium, or the grade of the concentrate will continuously decrease and the grade of the tailings will continuously increase. To ensure sufficient flotation time for the middlings and stable process indicators, the flotation time of the original ore must be extended to that of the middlings. Therefore, through the above - mentioned judgment criteria, the present invention finds a stable equilibrium state where the total yield of the concentrate and tailings and the grade of the tailings both reach stability. At this time, the middlings in the first - group experiment of the flotation closed - circuit experiment have been completely separated, and the time from the start of the second - group experiment of the flotation closed - circuit experiment to the first - reached equilibrium state is the time required for the separation of the middlings in the first group. Based on this time, the flotation design time can be preliminarily determined to ensure sufficient flotation time and effective separation of the middlings.

[0047] In this embodiment, the mass of the original ore sample for each group of experiments is 1000 g, the grade is 1.91 g / t, and the density is 2.75 t / m 3 , and a flotation machine with a flotation cell volume of 3 L is used for roughing and scavenging. The flotation test time is: 4 minutes for roughing, 4 minutes for cleaning, 3 minutes for the first scavenging and the second scavenging, and it is required that the grade of the flotation tailings is lower than 0.12 g / t. The relevant data are shown in Table 1 below.

[0048] Table 1 Statistical Table of Flotation Closed - Circuit Experiment Data of Ore Samples

[0049]

[0050] Analyzing the data in the table, it can be seen that in the 5th group of the flotation closed - circuit experiment, the yields of the concentrate and tailings reach the equilibrium state, and the grade of the tailings is stable at 0.1 g / t.

[0051] The calculation formula for the flotation design time is as follows:

[0052]

[0053] Among them, n represents the number of test groups when the laboratory closed-circuit flotation test first reaches the equilibrium state; t0 represents the open-circuit flotation test time, with the unit of min; m z represents the total dry weight of the middlings in a single-group test after the closed-circuit flotation test, with the unit of g; m0 represents the dry weight of the original ore sample fed into a single-group test in the closed-circuit flotation test, with the unit of g; V w represents the additional water volume in a single-group test in the closed-circuit test, with the unit of ml; V0 represents the volume of the flotation cell used in the closed-circuit test, with the unit of ml; q0 represents the aeration rate of the test flotation machine, with the unit of m 3 / (m 2 ·min); q represents the aeration rate of the industrial flotation machine, with the unit of m3 / (m2·min).

[0054] Substitute n = 5, m z = 494.9 g, m0 = 1000 g, t0 = 10 min, q0 = 2.78 m 3 / (m 2 ·min), q = 2 m 3 / (m 2 ·min), V w = 1550 ml into the above formula, and the calculated flotation design time is as follows:

[0055]

[0056] Therefore, the flotation design time of the newly built grinding and flotation production system is 34.1 minutes. In actual production, by sampling and calculating this process, the flotation time of this process is 34.6 minutes, slightly higher than the flotation design time. The reason is that fine control of the process is required to maintain ideal process indicators, and there is no reserved space for production expansion in this process, so the daily ore processing volume needs to be strictly controlled.

Claims

1. A method for determining the flotation design time based on laboratory closed-circuit flotation tests, characterized in that: The flotation design time is determined based on the data obtained from the closed-circuit flotation test. This data includes the minimum number of test groups required to reach the equilibrium state in the test, the total weight of middlings in a single test group after reaching the equilibrium state, and the data of the additional water volume in a single test group after reaching the equilibrium state. The calculation formula for the flotation design time is: T s = ； Among them, n represents the number of test groups when the laboratory closed-circuit flotation test first reaches the equilibrium state; represents the flotation open-circuit test time, with the unit of min; represents the total dry weight of the middlings in a single test group after the flotation closed-circuit test, with the unit of g; represents the dry weight of the original ore sample fed into a single test group in the flotation closed-circuit test, with the unit of g; represents the additional water volume in a single test group in the closed-circuit test, with the unit of ml; represents the volume of the flotation cell used in the closed-circuit test, with the unit of ml; represents the aeration rate of the test flotation machine, with the unit of m 3 / (m 2 · min); represents the aeration rate of the industrial flotation machine, with the unit of m 3 / (m 2 · min).

2. The method for determining the flotation design time based on the closed-circuit flotation test in the laboratory according to claim 1, wherein: The laboratory closed-circuit flotation test adopts a cyclic flotation method. In each round of flotation, concentrate, tailings, and middlings are produced, and the middlings are then floated again together with the newly added raw ore in the next round.

3. The method for determining the flotation design time based on the laboratory flotation closed-circuit test according to claim 2, wherein: After the closed-circuit flotation test is completed, calculate the yields of the concentrate and tailings and the grade of the tailings. If there exists a smallest possible integer n' that can satisfy the following conditions simultaneously: (a) Starting from the n'-th test, the fluctuation range of the combined yield of the concentrate and tailings is less than the preset value; (b) Starting from the n'-th test, the fluctuation range of the grade of the tailings is less than the preset value; Then take the integer n' as the number of test groups n when the equilibrium state is first reached.

4. The method for determining the flotation design time based on the laboratory flotation closed-circuit test according to claim 2 or 3, characterized in that: Each round of the laboratory closed-circuit flotation test includes one roughing, one cleaning, and two scavenging steps, as follows: (1) Start the first round of the test, add the raw ore, conduct roughing to obtain roughing concentrate and roughing tailings; conduct cleaning on the roughing concentrate to obtain concentrate and cleaning tailings; conduct the first scavenging on the roughing tailings to obtain scavenging concentrate and scavenging tailings; use the cleaning tailings and scavenging concentrate as the first middlings; conduct the second scavenging on the scavenging tailings to obtain tailings and the second middlings; record the additional water volume, filter and weigh the concentrate and tailings for standby, and uniformly dry, weigh, and assay the grade after the closed-circuit test ends. (2) Start the next round of the test, conduct roughing on the newly added raw ore and the first middlings of the previous round together to obtain roughing concentrate and roughing tailings; conduct cleaning on the roughing concentrate to obtain concentrate and cleaning tailings; conduct the first scavenging on the roughing tailings and the second middlings of the previous round together to obtain scavenging concentrate and scavenging tailings; use the cleaning tailings and scavenging concentrate as the first middlings of this round; conduct the second scavenging on the scavenging tailings to obtain tailings and the second middlings of this round; record the additional water volume, filter and weigh the concentrate and tailings for standby, and uniformly dry, weigh, and assay the grade after the closed-circuit test ends. (3) Return the first middlings and the second middlings of this round to the flotation process flow, repeat step (2), and conduct the next round of the test. After the weight data of the concentrate and tailings after filtration in each round of flotation is stable, continue to conduct 1 to 2 more rounds of tests, then filter, dry, and weigh the middlings of the last test group and record the weight.

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