Monitoring Phosphate Stockpiles in Morocco

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In the complex North Africa scenario, Morocco represents the best example of how political stability leads to economic, social and technological development. Morocco, a constitutional monarchy, where the country has remained relatively peaceful for centuries, enjoys a recently enacted new constitution which emphasizes democratic principles and freedoms. The country has embraced positive change, following the uprisings that in 2011 shook much of the region resulting in turmoil, which has strengthened it’s position as a regional economic and political leader.

The mining sector holds an important place in the Moroccan economy. For centuries, mining has been one of Morocco’s most practiced economic activities. Since the beginning of the twentieth century, major manganese, iron, zinc, lead and phosphate fields were discovered. The strongest point of Moroccan industry is phosphate mining which is managed by the state-owned Office Cherifien des Phosphates (OCP), Morocco is the world’s largest exporter and third largest producer representing 29% of the value of exports and employs over 20.000 workers. Having the world’s largest phosphate reserves estimated at 50 billion tonnes, Morocco and the Western Sahara came in second to China in terms of phosphate production for 2015. Producing 30 Mt of phosphate rock, Morocco may possess over half of the world’s reserves of phosphate.

Since 2014, the large Moroccan engineering firm, ETAFAT has deployed mobile mapping laser scanning (MMS) using Siteco Informatica’s MMS RoadScanner (Figure 1) for the evaluation of stockpile volumes of Moroccan phosphate mines.

Introduction to ETAFAT
Etafat is a leading company in Morroco in the geomatic fields. Since it’s establishment in 1983, ETAFAT is committed to contribute to main infrastructure projects in public and private sectors for land use and management of the Africa environment. Their services include data acquisition, processing and the creation of added value in delivered data and analysis products. A very special attention was paid to the company’s equipment with innovative technologies which include:
Laser scanning, extensive expertise in using the Faro 3D scanners for heritage conservation, evaluation of stockpile volumes and monitoring applications.
Mobile mapping using the SITECO’s RoadScanner 3 solution, employed in high-speed corridor acquisition of 360 images and point cloud data
Aerial photography through their own aircraft, equipped with digital cameras and LIDARS. More recently, UAVs are used in photogrammetry, precision agriculture and in close range data collection for complex structures
Hydrography with the use of single and multibeam echo-sounders.

Phosphate Mine Stockpile Monitoring
The phosphate mine project’s aim is to achieve the survey of 100 stockpiles on natural terrain (NT) and 12 mechanized stockpiles spread over a 30 km area (Figures 2 & 3). The required data density is 1 point per 10 cm2 with a margin of error on volume calculation not exceeding 1%. Data delivery deadlines by the seventh day after the start surveying for 100 stockpiles of NT, and the second day for mechanized stocks. The surveys are conducted once a month over a period of 24 months.

Configuration of the MMS
The Siteco MMS RoadScanner-3 is fitted with 3 Faro X330 laser scanners and a Point Grey Ladybug5 imaging system. An inertial navigation and positioning system, the Applanix Pos LV420 provides high precision vehicle position coordinates. An internal processor and memory is used to control all the subsystems, and an external laptop PC provides user control and interface functions.

Data Processing and Evaluation
The collected data is processed in 3 main phases:
1. Data Processing, Treatment of the Point Clouds: Includes calculating the trajectory and initial treatment of clouds and images in Siteco’s RoadSurvey RS-PostProcess. The trajectory processing takes into account the use of ground control points for improving the accuracy. Correction at this initial phase improves the trajectory of the order of 2 to 3 cm in good GPS reception conditions (Figure 4).

Results from the RS-PostProcess pointclouds and geo-referenced images can be viewed in video streams with images and pointclouds simultaneously overlayed. The pointcloud data, covering all areas of interest, provides for specific areas of feature and surface based extractions allowing for the later quantitative evaluation of stockpile volumes.

2. Export of point cloud and application filter for cleaning: The cleaning of the point cloud is based on filters including the individual point intensities. For this, noise selection parameters follow the distribution of the intensities of the cloud’s individual point values. Other noise removal filters duplicate and isolated points (Figures 5 & 6).

3. Calculations: Phosphate volume assessment and establishment of elevation maps are corrected by integrating the GPS ground control points. The noted differences are between 2 to 3 cm that are largely within the tolerances of the project. The calculation is performed thereafter based on the extracted surfaces and/or the contours of existing stocks. The generation of volumes is based on the incorporated area extracted from point cloud. The conversion to elevation maps allows easier visualization of phosphate storage levels (Figures 7 & 8).

Data acquisition speed using the mobile mapping system has exceeded deadlines and efficiency expectations in terms of all performance parameters. The point clouds are most representative of the actual field conditions compared to surveys only using GPS, and volume calculation has delivered the required accuracy. This has led to greater phosphate product reliability and workforce efficiency, both for the phosphate producers and their customers.

Thanks to this methodology ETAFAT has shown their ability to face the most advanced technological challenges of the Geomatics industry. This not only adds to economic prosperity, it encourages stability through promoting employment and export of goods, benefiting the entire population of 34 million. It is encouraging to see Morocco forging ahead into the future, setting the example of embracing modern technological advancement, encouraging peace and stability in the region.

Note: Original French language article by Mr. Kamal Benaddou Idrissi, Director General, and Mr. Najib Adouane, Head of Lasergrammetry Department, ETAFAT Ltd., Morocco. English adaptation and translation by Brent W. Gelhar, Spatial Initiatives Consulting, Canada.

Kamal Benaddou Idrissi graduated from the School of Surveyors and Topographers in 1991, and holds an MBA in Management. He incorporated ETAFAT in 1991 as an engineer project manager. Since 1999 he has been CEO and led the company to through ISO 9001 certification in 2003, During his leadership, ETAFAT has grown from 10 employees to 180. He has extensive teching experience in Moroccan (IAV Hassan II, EHTPs, Tanger FST) and French universities (ESGT, INSA Strasbourg).

Brent Gelhar is a technology commercialization consultant with more than 15 years experience in laser scanning hardware development. See for more information.

A 1.207Mb PDF of this article as it appeared in the magazine complete with images is available by clicking HERE