JPH028654B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to measuring the gold content of a metal-containing material,
In particular, it concerns the determination of the gold content of gold-bearing ore samples.

Gold is found in thin mineral layers deep underground, and when these mineral layers are mined, they also contain large amounts of useless ore. In order to process all the mined ore without expense or time, it is necessary to use some preliminary sorting process on the mined ore. Although many methods have been proposed for sorting ores to process them, no method of sorting that is completely satisfactory has been found so far.

Some methods are indirect and unsatisfactory because the relationship between measured secondary properties and gold content is uneven or imprecise, or otherwise method cannot meet the sample production rate required in the production environment.

The present invention is an apparatus for measuring the gold content of mined ore, which can meet the required production rate of the ore sample and which also uses the properties of gold itself to measure its content in the ore sample. Provide equipment that can.

According to the present invention, when measuring the gold content of a metal-containing material, neutrons are irradiated onto the body of the metal-containing material to be measured, and ¹⁹⁷ Au (nn') ¹⁹⁷ Au→279KeV is generated by the reaction. γ with an energy of 279KeV
An apparatus for measuring gold content by measuring line intensity is provided.

When using this method to measure the gold content of gold-bearing ores, Al, Si, Ca,
It is necessary to use a neutron source such that neutrons with energies above the neutron reaction threshold of elements such as Fe and O are not generated.
For example, suitable neutron sources include tubular neutron sources that use deuteron-deuteron or deuteron-beryllium reactions to generate neutrons.

Hereinafter, the present invention will be explained in detail by way of example with reference to the accompanying drawings.

Referring now to the accompanying drawings, gold-bearing ore 1 is fed to a hopper 2 which conveys the ore 1 to an ore crusher 3 where it is crushed into chunks 4 corresponding to a mesh size of 5 cm. The stream of crushed ore from the crusher 3 is split into multiple streams 5 (only one shown), which pass through a neutron irradiation assembly 6, described below. ore lump 4
Each stream of ¹⁹⁷ Au (nn′) Produced by ^197m Au
It is configured to detect gamma rays with an energy of 279 KeV. Each lump of ore 4 is individually interrogated to determine whether its gold content is above or below some predetermined content. For example, the critical content is
It is 5ppm. Generally, the gold content of each lump of ore is 1
or within the range of 10ppm.

There is a sorter 8 downstream of the gamma ray detection assembly 7,
Since this is a well-known type in the field of material selection, it will not be described in detail. This sorter 8 is γ
In response to a signal from the line detection assembly 7, each block 4 of ore passing therethrough is configured to be further processed or rejected.

Referring to FIG. 2, the neutron irradiation assembly 6 comprises a cylindrical body 21 made of lead, which is surrounded by a biological radiation shield 22 made to be impermeable to neutrons and gamma radiation. ing. The cylindrical body 21 has a central bore 23 around which six tubes 24 made of boron are arranged. These tubes 24 extend the entire length of the body 21. Each tube 24 has a bore such that only one flow of ore mass 4 can pass through the associated tube. In the central region of the bore 23 of the body 21 is a target 25 made of a material that generates neutrons in response to being impinged by a deuteron beam from a source not shown. This target 25 is suitably made of a material containing deuterons or beryllium. Constituent elements of gold-containing ores, namely aluminum,
It is important that the neutron source must be made of materials such as silicon, calcium, iron, and oxygen that do not generate neutrons of sufficient energy to cause fast neutron reactions. The target 25 emits neutrons over a solid angle of 4π, but the ore mass 4 passes through the maximum neutron field at an angle of 90° to the direction of the neutrons, so the energy of the neutron source is ¹⁹⁷ Au (nn' ) ^197m Au, but the neutron energy can be configured to be less than the threshold energy of the (n,p) reaction in the element, which is likely to be present in high concentrations in ores. In particular, care must be taken to keep the neutron energy below the threshold of the fluorine reaction: ¹⁹ F(n, α) ¹⁶ Nβ → ¹⁶ O (T1/2 = 7.3 seconds). This reaction is
Generates gamma rays with energies of 6.1 and 7.2 MeV. Although these are considerably larger in energy than the 0.279 MeV produced by ^{197 m} Au, their half-lives are the same, and the reaction becomes a source of low-energy impingement gamma rays with the same attenuation pattern as that to be detected. Therefore, especially when fluorine is present at a relatively high content compared to gold, it becomes difficult to estimate the gold content of the ore lump 4.

The gamma detection assembly 7 includes a linear array, not shown in detail, one for each stream of ore chunks. The signal operating the selector 8, which has six input channels, is derived from the combined output signal of each of the individual gamma detectors associated with each channel.

The neutron output of 10 ¹¹ n/s from the neutron source is 3
In 1 out of 100 measurements, a lump of ore with a gold concentration of 1 ppm can be distinguished from a lump with a gold concentration of 2 ppm, and in 99 out of 100 measurements,
To be able to distinguish a lump with a gold concentration of 2 ppm from a lump with a gold concentration of 5 ppm.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an ore sorting device according to the present invention;
and FIG. 2 is a cross-sectional view of a neutron irradiation assembly used in the apparatus of FIG. 1... Gold-containing ore, 2... Hopper, 3... Ore crusher, 4... Ore lump, 6... Neutron irradiation assembly, 7... γ-ray detection assembly, 8... Sorter.

Claims (1)

[Claims] 1. Means for passing individual samples of metal-containing material through a neutron source; ¹⁹⁷ Au(nn') ^197m Au→
means for measuring the intensity of gamma rays having an energy of 279 KeV generated by a reaction of 279 KeV;
¹⁹⁷ Au (nn') In response to the above method for measuring the intensity of γ rays generated by the reaction ^197m Au→279KeV, a sample of a metal-containing material having a gold content of more than a predetermined value is An apparatus for measuring the gold content of a metal-containing material, comprising: means for separating the metal-containing material from a sample having no gold content. 2. Neutrons are supplied by a tubular neutron source that utilizes a deuteron-deuteron reaction or a deuteron-beryllium reaction to generate neutrons, Claim 1
Measuring device as described in Section. 3 passing individual samples of metal-containing material through a neutron source, said means comprising a neutron source having insufficient energy to cause fast neutron reactions in the non-metallic components of the sample of metal-containing material; A plurality of tubes regularly arranged parallel to each other surrounding the outer periphery of a central tube suitable for the purpose of the present invention, and means for directing each sample of metal-containing material into said plurality of tubes. The measuring device according to item 1 or 2. 4 In relation to each of the plurality of pipes mentioned above,
4. Measuring device according to claim 3, wherein a separate gamma-ray detection channel and a screener responsive thereto are provided.