COLOR versus NIR/XRT

Sensor-based sorting of industrial minerals

1 Prinzipieller Aufbau eines Rutschensortierers ●
Structure in principle of a chute sorter

2 Colemanit und Störstoffe (Waste) aus der Lagerstätte Bigadiç/Türkei ● Colemanite and waste from the Bigadiç deposits/Turkey

3 Absorbtionskurven von Colemanit (blau) und Störstoff (rot) gemessen mit einem Bruker Spektroskop ● The absorption curves of colemanite (blue) and waste (red) measured using a Bruker spectroscope

4 Eindeutige Klassifikation zwischen Colemanite (blau) und Störstoffen (grün) ● Unequivocal differentiation between colemanite (blue) and waste (green)

5 PRO Granulate NIR ● PRO Granulate NIR

6 Scan zweier Referenzsteine (links Flintstein, rechts Kalkstein) aufgenommen mit einer CCD Kamera und das simulierte Sortierbild ● Scan of two reference minerals (left: flint, right: limestone) recorded using a CCD camera; simulated sorting pattern

7 Röntgentransmissions-Bild zweier Referenzsteine (links Flintstein, rechts Kalkstein) und das simulierte Sortierbild ● X-ray transmission image of two reference minerals (left: flint, right: limestone) and the simulated sorting pattern

8 PRO Tertiary XRT ● PRO Tertiary XRT

PRO Granulate NIR ● PRO Granulate NIR

Abstract

Color cameras have been used for many years in the improvement of industrial mineral products. The success of this technique depends on the product being differentiated by color from the unwanted material. New sensors are now also able to differentiate minerals unequivocally, irrespective of their colors. Significantly improved product qualities and higher product yields are thus achieved, compared to optical sorting. The benefits of sorting using a near-infrared (NIR) and an X-ray transmission (XRT) scanner become apparent upon comparison against color-camera sorting. Color-sorting of borate-containing mineral is firstly assessed against near-infrared sorting. The separation of limestone and flint, firstly by color, and then using X-ray transmission, is then comparatively assessed.

1 Introduction

Optical sorting of industrial minerals by color and brightness is state-of-the-art, and has frequently been examined in technical journals [1, 2, 3, 4]. Sorting of fillers and extenders, for example, improves quality-relevant parameters such as whiteness and yellowness index. Sorting of high-purity quartzes lowers iron, aluminium and titanium contents by rejecting colored and non-transparent impurities. The precondition for this is that the unwanted material is differentiated from the “value” (the product) by color. There must, therefore, be an adequate correlation between the...