Nearly 15 years ago, Phoenix Cement-then owned by Gifford-Hill-became the first cement producer in the world to purchase an on-line elemental analyzer for bulk materials. Beset with a complicated quarry and varying raw material composition, plant personnel were looking for ways to achieve more consistent chemistry in their pre-blending piles. In the company's Clarkdale, Ariz. plant, this goal was especially important since it has no corrective bins between the pre-blending piles and the raw mill; thus, the plant has to achieve the exact kiln feed chemistry it wants in these piles, just downstream of the crushers.

In 1984, Phoenix Cement took a chance on the then-new technology Prompt Gamma Neutron Activation Analysis (PGNAA) to address this operational challenge. The PGNAA process used neutrons and gamma rays to provide real-time analysis of cement raw materials, yielding minute-by-minute concentrations of SiO2, Al2O3, Fe2O3, CaO, and MgO, as well as alkali, sulfur, and chlorine.

The bulk material analyzer Phoenix Cement purchased was placed between the secondary crusher and the stockpiles, furnishing the operator with a continuous picture of the cumulative chemistry of the pile as it was being built.

As with any new technology, the new analyzer-designed by Gamma-Metrics-required a significant learning curve. Phoenix Cement contributed greatly to the early assessment of the product and, over the years, made numerous design suggestions to the vendor. Most significant was the shift from a vertical-chute configuration to a cross-belt analyzer (CBA). The CBA design, introduced in 1993, satisfied two of Phoenix Cement's major objectives: eliminate the need to replace chute liners several times a year, and avoid the potential of plugged chutes during the wet season.

Although Phoenix Cement deserves some credit for the new CBA design, ironically, it was not possible to upgrade the plant's chute analyzer to the cross-belt configuration. So for more than five years after the introduction of the CBA, the company continued to use its aging chute analyzer, while more than 50 cement producers throughout the world installed CBAs.

When Phoenix Cement finally decided to replace its chute analyzer with a CBA earlier in 1999, Gamma-Metrics had just introduced a new model of the analyzer dubbed the CB-GN. According to the manufacturer, this analyzer has digital signal processing, a smaller footprint, greater detector efficiency, reduced neutron source loading, and a more versatile user interface than the first-generation CBA. The analyzer, which has just been installed, also is meeting another objective of the Phoenix Cement staff by offering a reduced and simplified learning curve.

A division of the Salt River Pima-Maricopa Indian Community since 1987, Phoenix Cement currently is undergoing a facility-wide modernization that will increase productivity using a more fuel-efficient, environmentally sensitive production process.

According to company President Roger Smith, the CB-GN is an integral part of this renovation. "The analyzer is proving itself a valuable tool for improving both quality and productivity," said Smith. "The CB-GN's features help us produce superior products on a consistent basis."