METHOD FOR DETERMINING THE BULK DENSITY OF BULK MATERIAL IN A MOBILE CRUSHER

Abstract

A method determines the bulk density of bulk material (2) in a mobile crusher, in which the bulk material volume of bulk material (2) delivered onto a conveyor belt (1) is determined. The method is configured such that the bulk material weight can be determined reliably over a relatively prolonged operating period of a mobile crusher, even with varying bulk material density. Both the bulk material volume and the bulk material weight of a conveyor belt section (3) are sensed in successive time steps, and the bulk density is determined from the quotient of the bulk material weight and the bulk material volume.

Claims

1. A method for determining the bulk density of bulk material in a mobile crusher, said method comprising: feeding a bulk material onto a conveyor belt; detecting both a bulk material volume and a bulk material weight of the bulk material on a conveyor belt section in successive time steps; and determining the bulk density from a quotient of the bulk material weight and the bulk material volume.

2. The method according to claim 1, wherein a bulk density mean value is derived from the bulk densities of preceding time steps, and a disturbance signal is output when a difference between the bulk density and the bulk density mean value exceeds a maximum permissible difference.

3. The method according to claim 2, wherein at least one measurement state variable of the conveyor belt is determined for each time step and, when the difference between the bulk density and the bulk density mean value exceeds the maximum permissible difference, if the measurement state variable of the conveyor belt deviates from the measurement state variable of the last time steps, a corrected bulk material weight is determined from the bulk material volume and the bulk density mean value.

4. The method according to claim 2, wherein at least one measurement state variable of the conveyor belt is determined for each time step and, when the difference between the bulk density and the bulk density mean value exceeds the maximum permissible difference, if the measurement state variable of the conveyor belt remains constant compared to the measurement state variable of the last time steps, a corrected bulk material volume is determined from the bulk material weight and the bulk density mean value.

5. The method according to claim 3, wherein the bulk material volume and the bulk material weight are recorded for each time step, and the corrected bulk material volume is determined as bulk material volume and/or the corrected bulk material weight is determined as bulk material weight for the ti me steps at which a disturbance signal was output.

6. The method according to claim 3, wherein at least one measurement state variable of the conveyor belt is determined for each time step and, when the difference between the bulk density and the bulk density mean value exceeds the maximum permissible difference, if the measurement state variable of the conveyor belt remains constant compared to the measurement state variable of the last time steps, a corrected bulk material volume is determined from the bulk material weight and the bulk density mean value.

7. The method according to claim 6, wherein the bulk material volume and the bulk material weight are recorded for each time step, and the corrected bulk material volume is determined as bulk material volume and/or the corrected bulk material weight is determined as bulk material weight for the time steps at which the disturbance signal was output.

8. The method according to claim 4, wherein the bulk material volume and the bulk material weight are recorded for each time step, and the corrected bulk material volume is determined as bulk material volume and/or the corrected bulk material weight is determined as bulk material weight for the time steps at which the disturbance signal was output.

Description

BRIEF DESCRIPTION OF THE INVENTION

[0011] In the drawing, the subject matter of the invention is shown by way of example, wherein:

[0012] FIG. 1 shows a schematic side view of a device for carrying out the method according to the invention, and

[0013] FIG. 2 shows a flow diagram of part of the method according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] A device for carrying out the method according to the invention comprises a conveyor belt 1 which transports bulk material 2. The bulk material 2 of a conveyor belt section 3 is measured by a scale 4 and an optical scanning system 5, wherein the scale 4 determines the bulk material weight on the conveyor belt section 3 and forwards it to a computer unit 6. The scale 4 can be, for example, a roller chair belt scale or, in a particularly preferred embodiment, an electric power scale. The optical scanning system 5 measures the bulk material 2, and also sends the measurement data to the computing unit 6, which determines the volume of the bulk material 2 from the measurement data. On the conveyor belt 1, there are also sensors for determining the measurement state variables, such as an inclination sensor 7 and a speed sensor 8, which transmit the inclination and speed of the conveyor belt to the computing unit 6. In addition, there may be sensors for determining other measurement state variables, such as the operating temperature and the position of the crusher. These may, for example, also be accommodated in the housing of the inclination sensor 7. The computing unit 6 is equipped with a disturbance signal transmitter 9, which informs a user of changes in the measurement conditions.

[0015] By means of the computing unit 6, bulk material weight, bulk material volume and bulk density are determined from the measurement data, wherein first the maximum permissible difference between bulk density and bulk density mean value and the maximum permissible change in the measurement state variables on the conveyor belt 1 are stored in the computing unit 6.

[0016] As can be seen in particular from FIG. 2, first of all in step 10 for each time step the bulk material weight, the determined bulk material volume, as well as the measurement state variables of the conveyor belt section 3 are read in, and the bulk density is determined from the bulk material weight and bulk material volume. In addition, in this step the bulk density mean value is formed from a predetermined number of bulk densities of past time steps.

[0017] In step 11, it is checked whether the maximum permissible difference between bulk density and bulk density mean value is exceeded.

[0018] If this is not the case, step 12 follows, in which the measured bulk material weight, bulk material volume and the bulk density determined from these are stored for this time step.

[0019] However, if the maximum permissible difference between the bulk density and the bulk density mean value is exceeded, step 13 follows, in which a disturbance signal is output. In step 14, it is then determined whether the maximum permissible change in the measurement state variable of the conveyor belt has been exceeded.

[0020] If this is not the case, step 15 follows, in which it is assumed that the optical scanning system 5 has supplied incorrect values for this time step and that the scale 4 supplies reliable values. The measured bulk material weight is therefore stored for this time step. The bulk material volume is determined as the quotient of the bulk material weight and the bulk density mean value determined in step 10 and stored for this time step. For this time step, the last valid bulk density or the bulk density mean value can be stored as the bulk density.

[0021] If the maximum permissible change in the measurement state variable of the conveyor belt is exceeded, step 16 follows, in which it is assumed that the scale 4 has supplied incorrect values due to the change in the measurement state variable at the conveyor belt section 3 and the optical scanning system 5 supplies reliable values. The measured bulk material volume is therefore stored for this time step. The bulk material weight is determined as the product of the bulk material volume and the bulk density mean value determined in step 10 and stored for this time step. For this time step, the last valid bulk density or the bulk density mean value can be stored as the bulk density.