Tailings recovery has been a constant challenge for most engineers. Along more than five years, GAUSTEC joined major players in the mining Industry to scavenge Iron from tailings produced by flotation making use of WHIMS (Wet High Intensity Magnetic Separation). In the early 1980s, in USA, the US 4,192,738 patent was granted with promising results. Despite this, thirty years have passed with no significant application worldwide. One main reason is reported: the market missed a really high feed capacity WHIMS in order to avoid the huge number of the WHIMS that were available at that time (such projects would typically require more than 20 WHIMS to scavenge iron from tailings produced by flotation plants). Such a huge asset to scavenge low grade iron tailings would not payback. The Mega sized WHIMS launched by GAUSTEC in 2014, the GHX-1400, improved by the Super-WHIMS Technology (18.000 Gauss) and BigFlow Magnetic Matrixes (Gaps smaller than 1.5 mm), faced this challenge. Specially designed ancillary equipment described here also played a decisive role in the scene.

Ten years of continuous research and development have led to a major improvement in the field of iron ore Wet High Intensity Magnetic Separation - WHIMS. With this cutting-edge technology, Gaustec has established a new world record in this class of Magnetic Separators, by providing a sheer feed rate of up to 1400 tph for iron ore fines. Although low-grade iron ore mines will benefit from this new technology, focused on herein is the reclaiming of low-grade iron ore tailing from ponds, having in mind its huge positive environment impact and business opportunity. Based on this newly developed technology, the construction in Brazil of a Concentration Plant started in 2012 for dressing iron ore tailings at 45% Fe grade, at Itaminas Mine. This plant went into operation this year. Based on the good performance of this first unit, the construction of a second Concentration Plant of the same type, to further reduce to 18% Fe in the tailings, is under way, scheduled to be started-up in 2014.

Since its introduction in 1963 by G.H. "Jones", WHIMS MS has proven to be, worldwide, a major technology for separating several types of ore fines from their contaminants. Unfortunately, despite its superb characteristics, even if the best operational procedures are followed, one main issue lasts. It is the blocking of the matrix gaps by oversized particles. Protection screens have been employed to wipe out this blockage, though only partially effective. Creative methods and tools have been developed to facilitate and speed up the cleaning process. But, in fact, along 50 years, the matrix blockage nightmare lingered defying the minds involved with Whims operation. The recent environment demands and the need to reduce costs by recovering ore ultra-fines currently being disposed in tailing ponds, further posed a new challenge. Reportedly these ore ultra-fines, typically below 75 microns, demand smaller gaps for its recovery than today's bottom limit 1.5 mm. The blockage issue worsens even more and to solve it, Gaustec Magnetism, after two years of research and test work, finally succeeded in developing The Brand New NoBLOCK® Technology presented here.

The Magnetic separation of ultra-fine ore particles has always posed a challenge to the JONES/WHIMS process. Despite many advances in this technology, no effective improvement has been made to its core component: The Magnetic Matrix. The current approach to separate ultra-fine particles teaches that the gap of the matrix and its teeth size must be smaller than usual in order to accommodate the small size of the particles. However, practice proved this approach to be far from ideal. The closing of the gap between grooved plates, whose teeth are smaller, drastically reduces the flow area, reduces the feed capacity, and makes the matrices prone to clogging. In addition, smaller teeth reduce the magnetic field and its gradient, leading to poor results with ultra-fine ore particles. This research proves that bigger teeth are better suited for high intensity magnetic separation of ultra-fines because they avoid matrix clogging thanks to the larger slurry flow area. Additionally, bigger teeth amplify the magnetic field "Bmax" and increases the magnetic gradient "Grad (∆B /∆X)". The positive results of this new "BigFLUX Matrix" technology, are being displayed in several mining operations worldwide, increasing metallurgical recovery and producing high quality concentrates and low iron content sand from iron ore tailings.

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Proper development and zonation of the adrenal cortex is intimately connected with its lifelong capacity to produce steroid hormones. Both adrenocortical development and homeostasis are mediated in part by paracrine WNT/β-catenin signaling, an essential pathway for zonal maintenance and aldosterone production. Patients harboring homozygous or compound heterozygous loss-of-function (LOF) mutations in the WNT ligand WNT2B present with congenital diarrhea and require parenteral nutrition. Despite evidence for euvolemia, WNT2B-null patients exhibit markedly elevated plasma renin levels with no corresponding increase in aldosterone, suggesting a primary adrenal defect in aldosterone synthesis. To test this hypothesis, we generated both global and conditional Wnt2b knockout mouse models. In the mouse adrenal, Wnt2b is expressed exclusively in the capsule, the outer compartment of mesenchymal cells that overlay and signal to the subcapsular zona glomerulosa (zG), the adrenocortical zone that harbors aldosterone-producing cells and critical long-term progenitor cells. Global loss of Wnt2b from early mouse development results in a near-complete absence of the histological zG. Moreover, Wnt2b-null mice exhibit significantly increased plasma renin but normal aldosterone levels compared to wild-type controls. These data suggest that WNT2B-null patients indeed have an adrenocortical phenotype caused by apparent zG hypofunction. To further define the mechanism(s) by which Wnt2b LOF leads to zG hypofunction, we temporally deleted Wnt2b in the adrenal capsule of adult mice. Wnt2b conditional knockout (cKO) adrenals exhibit a zG-restricted decrease in Wnt/β-catenin signaling as determined by decreased β-catenin activity and target gene expression. Moreover, Wnt2b cKO mice demonstrated a disorganized zG and disrupted adrenocortical zonation. To determine the contribution of WNT2B to aldosterone production, we administered a sodium-deficient diet to control and Wnt2b cKO mice to activate the renin-angiotensin-aldosterone system. Indeed, while control mice exhibited the expected increase in both plasma renin and aldosterone, Wnt2b cKO mice showed marked elevation of renin despite normal aldosterone compared to controls, consistent with hyperreninemic hypoaldosteronism. Together, our work supports a WNT2B-dependent mechanism for adrenal zG development and maintenance in mice and humans and provides relevant models to study the consequences of WNT2B deficiency within the zG. Presentation: Saturday, June 11, 2022 11:45 a.m. - 12:00 p.m.

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