JPS6268559A - Method of controlling froth flotation by using bubbler tube - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for separating impurities such as ash from raw material by froth flotation. More specifically, on the one hand, the present invention controls the froth flotation of coal by adjusting the addition rate of the froth-enhancing additive in response to the measurement of the concentration of the mixture in the froth flotation unit. Regarding the method. On the other hand, the present invention relates to controlling a froth flotation unit by adjusting the rate of discharge of impurities from the froth flotation unit in response to a measurement of the liquid level of a valve within the froth flotation unit.

BACKGROUND OF THE INVENTION A mixing control device is described in US Pat. No. 3,532,102. This mixing control [I device controls one of the two divided liquids supplied to the mixing chamber to control the softness, concentration, and pH of the mixed liquid.

U.S. Pat. No. 3,499,580 describes a pressure transmitting device and member. In order to obtain a pressure value on the liquid along the discharge tube, the bubbler tube is provided with an open outlet end located below the surface of the liquid. While bubbles are being generated from the bubbler tube, the pressure inside the bubbler tube indicates the pressure within the liquid that has entered the end of the bubbler tube, and the height between the end of the bubbler tube and the discharge pipe into which the liquid has entered. By measuring the difference, it can be used as an indication of the pressure within the liquid forcing the liquid along the drain tube. It is explained in detail in No. 111II, lines 54-64.

U.S. Pat. No. 2,886,051 describes an apparatus for controlling a homogeneous mixture of liquid and solid matter, such as ore, in water. No. 2,886,051 describes that many devices for measuring the concentration of mixed liquids in a sorting line use bubbler tubes as the basic component.

US Pat. No. 2,577.548N describes a corrected specific gravity measurement.

U.S. Pat. No. 4,006,635 describes a liquid level measurement method and a pressure gauge using first and second spray static pressure probes, the first probe being located near the bottom of the tank; The second probe is located slightly below the highest liquid level. The differential pressure and electrical voltage transducer is the first
and a second probe.

U.S. Pat. No. 3,613,456 describes a method for generating air bubbles in a liquid and an apparatus comprising at least one set of bubbler tubes, in which humid gas is used as the flow pair of the bubbler.

U.S. Pat. No. 3,551,897 describes a method for controlling the flotation of ore using analog or digital computers, which efficiently utilize various measurements.

U.S. Pat. No. 4,252,139 describes a method and apparatus for automatically mixing solutions with defined concentrations.

U.S. No. 4.393.705 uses pipes of varying vertical heights within the liquid in the reservoir, which are constantly pressurized by a gas, usually air, to increase the specific gravity of the liquid in the reservoir. and the height of the liquid level is measured.

U.S. Department of Energy's “Latest Information on Coal Preparation Plant Automation”
(ORNL-3699, February 1982) 48-52
The page describes regulating the flow of impurities in coal beneficiation by froth flotation to control the liquid level as measured by a metering tube with one leg.

Empirotic Corporation (1: nviro) for the Electric Power Research Commission
Tech Corporation) report (
4-25 to 4-32 (June 1981) describe short-term flotation in coal froth flotation, preferably using feedback control from on-line measurements, and It describes the operating procedures for changing the process accordingly.

[Summary of the Invention] According to the present invention, in a method for separating coal from a mixed liquid of coal and impurities in a froth flotation unit, The difference in back pressure between the two bubbler tubes is measured, and the addition rate of the froth-increasing additive to the mixed liquid is controlled in response to the measured change in the concentration of the mixed liquid. In accordance with an embodiment of the invention, the difference in measured backpressure is used to adjust the backpressure of a single bubbler tube, a measurement representing a defined liquid level, to vary the concentration of the mixture. Additionally, the signal indicative of the actual liquid level is used to adjust the rate of impurity efflux from the froth flotation.

According to this invention, the following advantages can be obtained.

Two fundamental variables that indicate the performance of the froth flotation unit, namely the height of the liquid level and the concentration of the liquid mixture, are measured by one device.

Using this device it is possible to control the rate of addition of reagents to the froth flotation unit based on the steps carried out within the flotation unit. Many conventional control devices are expensive and complex. Conventional controllers utilize densitometers, which are typically inaccurate, to measure the concentration of material entering the froth flotation unit. According to the invention, the concentration of the mixed liquid in the froth flotation unit can be measured by using different bubbler tubes without using an inaccurate concentration meter.

The basic control of the liquid level within the froth flotation unit is carried out by the rate of flow of impurities from the froth flotation unit. The liquid level in the froth flotation unit is affected by the concentration of the mixed liquid, but according to the control method of the present invention, the influence of concentration can be compensated for, and the level of the three-phase mixture (air, liquid, solid) can be adjusted. is expressed.

By varying the flow rate of the foaming agent and scavenger, the concentration of the mixture and the recovery of coal from the product can be varied.

According to the control method of the present invention, stability of the froth flotation unit can be provided.

(Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

In FIG. 1, raw fabric containing coal and impurities is supplied to a mixer 5 via a pipe 2. The foaming agent contained in the first container 23 is supplied to the first pump 25 via the line 24 . A first pump 25 injects this foaming agent into the mixer 5 via line 3. The scavenger in the second container 21 is supplied to the second pump 20 via a conduit 22 . A second pump 20 injects this scavenger into the mixer 5 via line 4 . Stirring in the mixer 5 is performed by a stirring section 7 fixed to a rod 8, and this stirring section 8 is rotated by a motor 9. A liquid mixture of the original fabric, a foaming agent, and a scavenger is supplied from the mixer 5 to the froth flotation unit 1 via a pipe 6. The coal component of the raw fabric is discharged through the line 40 of the mixer 5, and the impurities of the raw fabric are discharged via the line 10.

A pressure control valve 26 is disposed in the air supply pipe 27 . From the air supply conduit 27, air is supplied to conduits 29 and 30.
supplied to The air supplied to the pipe line 29 is transferred to the pipe line 41
through the first rotometer 28. Conduit 41
is connected to a short bubbler tube 12. Pipeline 3o
The air supplied to the pipe 42 is connected to the second rotometer 31
flowed in through. The conduit 42 is a long bubbler tube 1
It is connected to 3.

FIG. 1 shows the highest level 39 of the liquid-solid mixture in the froth flotation unit 1. The distance between the highest level 39 of the liquid mixture in the froth flotation unit 1 and the lower end surface of the hot bubbler tube 12 is indicated by Y in FIG.

The distance between the highest level 39 of the liquid mixture in the froth flotation unit 1 and the lower end surface of the long bubbler tube 13 is indicated by X in FIG. The distance between the lower end surface of the short bubbler tube 12 and the lower end surface of the long bubbler tube 13 is
It is indicated by 7 in FIG.

The air supplied through the short bubbler tube 12 and the long bubbler tube 13 provides a back pressure equal to the displaced hydrostatic head, which is applied to the differential pressure transducer 14.
and is measured by the pressure quadrature transducer 15. Differential pressure transducer 14 and pressure quadrature transducer 15 send input signals to microprocessor 17 . Microprocessor 17 is programmed with proportional, integral and differential algorithms.

The microprocessor 17 sends the signal to the first pump 25.
via line 18 to control the rate of foaming agent addition. A signal is transmitted via line 19 to the second pump 24 to control the scavenger addition rate. Microprocessor 17 transmits signals to valve 11 via line 38 to control the rate of impurity flow.

Due to the differential pressure transducer 14, a signal proportional to 2 is transmitted to the concentration recorder 16 via line 43 and to the microprocessor 17 via line 44. Differential pressure transducer 14 is connected to line 46 and line 4.
7 and receives an input signal via line 48. Line 47 is connected to short bubbler tube 12 and line 48
is connected to a long bubbler tube 13.

The pressure transducer 15 is connected to the long bubbler tube 13 via line 49.

Pressure quadrature transducer 15 transmits a signal proportional to X to microprocessor 17 via line 50.

Level recorder 34 is connected to microprocessor 17 via line 45. A level recorder 34 and a concentration recorder 16 provide a continuous graph printout of the liquid level and concentration within the flotation unit 1 on paper.

A second valve 32 is provided in the conduit 42 of the second rotometer 31.
is provided, and the flow rate of the air passing through the second rotometer 31 is controlled by the second valve 32. Similarly, a first valve 33 is provided in the conduit 41 of the first rotometer 28, and the flow rate of air passing through the first rotometer 28 is controlled by the first valve 33. The first valve 33 and the second valve 32 are adjustable flow rate regulating valves.

FIG. 2 shows another embodiment of the invention, and in this other embodiment, the same members as in FIG. 1 are given the same reference numerals.

In FIG. 2, the 1
The flow rate of one or more reagents is maintained constant by a main control loop, which control loop is connected to a flow transmitter 52.
The flow transmitter 52 has a flow rate in the conduit 4]
and via line 54 the flow controller 5
A signal corresponding to the flow rate is transmitted to 6. Flow controller 56 in turn sends a control signal to feed pump 20 on line 5.
8. In response to a signal from line 60, which will be described below, the constant flow rate in conduit 4 is readjusted if it becomes necessary to adjust the set point of flow controller 56.

The immobile bodies in the froth flotation unit 1 are essentially three-phase, i.e. the suspension of solids within the liquid is subject to a draft that generates floating bubbles, and this draft flows from the vibro 2 to the sparger 64.
This is caused by air flowing into the area. As described in the embodiment of FIG. 1, a signal 44 indicative of a distinct liquid concentration is generated by short bubbler tube 12 and long bubbler tube 13 and detected by differential pressure transducer 14. This signal 44 is communicated to controller 16 which generates a reset signal on line 60. The liquid concentration indicates the separation of solids in the froth flotation unit 1 and is used to adjust the addition rate of agents such as foaming agents and scavengers.

As explained in the embodiment of FIG. 1, the lever controller 34 combines the signal from the line 44 with the signal from the pressure transducer 15 to provide a concentration correction depth signal to the line 66, which causes the valve to 11 is adjusted to maintain a constant liquid level within the froth flotation unit 1.

Note that various modifications can be made without departing from the gist of the invention.

[Brief explanation of drawings]

1 is a schematic diagram illustrating one embodiment of the invention and the use of a microprocessor to process measurements and provide control signals; FIG. 2 is a schematic diagram illustrating another embodiment of the invention; FIG. . 1... Floss flotation means (floss flotation unit), 12
... Bubbler tube (short bubble tube), 13.
・・Bapura tube (long bubble tube).

Claims (5)

[Claims] (1) A froth flotation means, two different bubbler tubes placed at different depths from the liquid level in the froth flotation means, and a mixed liquid containing coal and impurities to be sent to the froth flotation means. and supplying gas through the bubbler tubes while measuring the back pressure difference between the two bubbler tubes and the back pressure of any one bubbler tube; providing a first control signal proportional to the ratio of the difference in backpressure between two bubbler tubes to the backpressure of any one bubbler tube, and a second control signal proportional to the backpressure; a step of supplying a liquid mixture of coal and impurities to the froth flotation means to float the coal and discharge impurities, and discharging the coal from the froth flotation means in response to a change in the first control signal; and a step of controlling an addition rate of a froth-increasing additive added to the froth flotation means in response to a change in the second control signal. A method of controlling flotation using bubbler tubes. (2) A method for controlling froth flotation using a bubbler tube according to claim 1, wherein the froth-increasing additive comprises a foaming agent and a scavenging agent. (3) A method for controlling froth flotation using a bubbler tube according to claim 1, wherein the froth-increasing additive includes a foaming agent. (4) a step of supplying a mixture of coal and impurities to a flotation region; and a step of providing two bubbler tubes placed at different depths in the mixture of coal and impurities in this flotation region; supplying gas through each of these two bubbler tubes and measuring the difference in back pressure between the two bubbler tubes to provide a first control signal; Controlling froth flotation using a bubbler tube, the method comprising the steps of: supplying an augmentative additive; and adjusting the flow rate controller in response to a change in a first control signal. how to. (5) measuring the back pressure of the gas supplied through the bubbler tube within the mixture in the flotation region to provide a second signal; and a third signal proportional to the ratio of the second signal to the first signal. A bubbler tube according to claim 4, characterized in that the bubbler tube comprises the steps of: generating a third signal; and controlling the discharge rate of impurities from the flotation region in response to the third signal. How to control flotation using floss.