Robert Gerhard Merker

Freelancer, Master of mineral processing engineering

For nearly 40 years, I've been working in the raw materials industry as a mineral processing engineer.

A profound course of studies at the famous mining school of Freiberg (Bergakademie) has been a sound basis of my professional career.

I've been working successfully on various positions, and interesting tasks in the line of development, production and marketing, finally as an industry consultant.

My special skills and know-how provide a helpful service in all terms of mineral engineering, reclamation and use of secondary & primary raw materials.

I keep on being active as an independent freelancer, and offer my senior experience for your benefit with pleasure.

My references are shown in detail in this part of my web-site. rgmr

1976 – 1981

Mining University Freiberg/ Germany (Bergakademie)

  • studies of mineral processing / mechanical processing engineering, graduation as a master of engineering (Dipl.-Ing.), engineers degree project: china clay processing, diploma thesis: flotation of poor tin ores.

1991 – 1992

College of Chemistry Fresenius Wiesbaden (Chemieschule Fresenius)

  • professional training in industrial environmental pollution control, contaminated sites management, hazardous materials and waste management.

1981 - 1990

Mineral Raw Materials Consulting Dresden GmbH, (geological industry)

research associate and project manager,

  • project development, exploration of mineral deposits, process and product development, basic engineering, feasibility study rare earths (RE) ores etc.

1992 - 1995

B.U.S Environmental Services (Berzelius- Umwelt-Service AG)

(plants of processing and recycling of residues from the metallurgical industry)

Project engineer and project manager,

  • pilot tests, process development, engineering, plant construction, application engineering of secondary raw materials, product and market development

1996 - 2003

Aluminum Salt Slag Treatment Hanover und Luenen (ALSA GmbH)

(treatment and recycling plants of salt slags from Aluminium smelters)

Project manager, since 1997 head of Alumina sales and process development,

  • build-up of a secondary Alumina market in Germany and Central Europe, application engineering, product development,
  • process development, planning, construction and commissioning of processing plants in Germany, Norway and Canada

2004 - 2005

Recyclage d’Aluminium Québec Inc. Becancour/ Canada, later on ALSA Canada

(Al-smelters and salt slag treatment)

Consultant and manager of marketing and product development,

  • commissioning and de-bottlenecking of a Salt Slag processing facility
  • product and market development for Alumina in North America

2005 - 2009

Aluminum Salt Slag Treatment Hanover, Luenen and Toeging, (ALSA GmbH, now BEFESA Salzschlacke), in Germany

head of application engineering and product development,

  • expansion of an Alumina market towards South Germany and Southeast Europe
  • green field project site evaluation, commissioning and de-bottlenecking of processing facilities
  • Project management, product and process development

from 2010 on

Freelancer (R. Gerhard Merker – mmp)

  • consulting for raw material producer and trader, recycling and processing facilities, etc.
  • sourcing and supply of Alumina, mill scale, Iron ore, micro silica, Silicon carbide, Silicon, Iron sulphate, fly ash etc.
  • raw material sourcing and consulting for portland and special cement kilns, flux blenders, mineral wool facilities, etc.
  • market development and studies about secondary raw materials like Alumina, Magnesia, dross etc.
  • process deveolpment and engineering for processing respectively recycling of salt slags, Alumina, Silicon by-products, Rare Earthes, Tin-, Lithium- and Gold ores etc.
  • consulting of REACH- and CLP-procedures, development of a product status
  • consultant for processing tests of rare earth exploration projects ( for CRC among others)


1984 - 1988, from 2016

technical consulting, ore reserve evaluation, pilot tests, planning of a green field rare earth mining project

Belgium, France, Scandinavia, Poland, Hungary, Czech, Austria, Sweden etc.:

from 1994

PEA salt slag, acquisition / customer care/ application engineering (cement kilns, mineral wool, steel mills)



permit application, plant site evaluation, planning of a brown field salt slag project



Aluminium recycling seminar in Sao Paolo,

USA / Kanada:

2000 - 2008,

salt slag project development, plant planning, site evaluation, consulting, commissioning, manager of product and market development,

from 2011 on

consultant for metallurgical tests and process engineering, REE exploration + PFS projects, Nb/Ta-ores, Gold/Copper plants

middle East:

from 2011 on

consulting for Aluminium dross processors

Geological exploration:

Rare Earthes ores (REE), Feldspar, Quartz, Gold/Copper ores, Nb/Ta-ores, Bentonite,

Raw materials and commodities:

Quartz, Feldspar, Bentonite, REE-Y-ores, Col-Tan ores, Heavy Mineral sands, Baryte, Talcum, Tin/tungsten ores, Gold-Copper-Sulfide ores, Li-ores, China clay, Alumina, Aluminiumhydroxide, Aluminium Metal, Aluminium dross, Silicon,SiC, Arc furnaces steel mill dust, Waelzkiln slag, Foundry sand, Al- and Mg-Salt Slags and cakes, Bypass dust from cement kilns, Potash

Processes and techniques:

  • Flotation of REE-Y-minerals, Fluorite, Baryte, Mica, Li-minerals, Cassiterite, Potash, gold, sulfides etc.;
  • Magnetic separation and purifying of REE-minerals, Ilmenite, Mica, Fe-minerals, Aluminium oxide, Aluminum
  • Electrostatic separation of Silicon and Heavy minerals;
  • Eddy current separation of metals like Magnesium and Aluminum,
  • Gravity separation of REE, Gold, Tin and Col-Tan minerals;
  • Wet and dry processing/milling of Al- and Mg-salt slags as well as various ores;
  • Processing of various ores, Feldspar, Aluminium oxide, China clay etc.;
  • Classifying of Aluminium oxide, metals, Salt slags, ore slurries, China clay, etc.;
  • Autogenous comminution of Salt slags;
  • Screening of Aluminiumoxide, Aluminium hydroxide, Feldspar;
  • Calcining of ceramic products, secondary Alumina, Calcium Aluminates;
  • thermical purification and upgrading of Alumina from salt slag and dross processing;
  • Drying of Alumina, Aluminum, ore concentrates;
  • Pelletizing of Aluminium hydroxide, ceramic mixings, Steel mill dust, Bypass dust;
  • Briquetting of Stell mill dust, Aluminium hydroxide, Alumina, Silicon etc.;
  • Filtration of China clay, ore slimes, Aluminium hydroxide, Salt slag;
  • Dedusting and cleaning of dryers and calciners off-gases;
  • Melting of Alumina etc.;
  • Mechanical and pneumatical conveying of dusts, bulk materials, etc.;
  • Crystallization of Chlorides
  • Processing of Gold/Copper-ores

Ore processing:

1985 - 1989:

Rare Earthes Ores of Dong Pao/Vietnam:

development of a processing technique, basic engineering, (grinding, flotation, classifying, magnetic separation, filtration, drying, acidic leaching), site evaluation, mine and facility planning, feasibility study for 40 kt/y of ore input

2012 - 14:

Rare earth ore Ashram/Eldor/Canada:

development of a flotation technique for a Monazite + Bastnaesite bearing carbonatite rare earth ore, consulting for a PFS (CRC)

from 2016 on:

REE study Vietnam

from 2016 on:

Gold-Copper US

Consulting for a pilot plant operation, project development

Salt Slag processing:

1995 - 2009:

operation of Best-Available-Technology Salt Slag treatment plants at Luenen 170 kt/y, Hanover 110 kt/y, Toeging 100 kt/y in Germany (crushing, milling, screening, leaching, oxide filtration, chloride crystallization, off-gas washing, fertilizer production, etc.)

1998 - 2003:

process development and pilot processing tests of German, Canadian and Norwegian Salt Slags;

1997 / 1998:

development, construction and commissioning of a wet milling facility (milling, screening, magnetic separation, metal drying, off-gas washing) at ALSA Luenen/ Germany, 60 kt/y Al–Salt-Slag-fines input

2001 - 2004

development, planning, commissioning of a sophisticated processing plant (wet milling, screening, magnetic separation, leaching, oxide filtration, oxide curing and drying, chloride crystallization, off-gas combustion, etc.) at RAQ Inc. in Becancour /Canada, 30 kt/y slag input capacity


development, planning and permit application of a Salt Slag processing plant (crushing, wet milling, screening, filtration, leaching, crystallization etc.) at Hydro Aluminium in Karmoy /Norway, 50 kt/y capacity

2006 - 2008

construction, commissioning and de-bottlenecking of a Salt Slag processing plant (wet milling, screening, magnetic separation, leaching, oxide filtration, oxide curing and drying, crystallization, etc.) at ALSA Sued in Toeging/Germany, 100 kt/y input capacity


PEA study salt slag East Europe


1994 / 1995

development, construction and commissioning of a mixing and pelletizing facility of Steel Mills Arc Furnace dust and coke breeze at B.U.S Zinkrecycling Freiberg/ Germany, 100 kt/y capacity

Press filtration:

1999 / 2000

development, construction and commissioning of a press filtration facility of secondary Alumina at ALSA GmbH Luenen/Germany, ard. 100 kt/y output capacity



pilot tests and basic engineering of a fluidized bed calcining facility to produce high value ceramics from secondary Alumina, BUS AG

2001 / 2002:

development, planning and permit of a brown field calcining project (mixing, pelletizing, rotary kiln, cooler, screening, silo storage, packaging, off-gas cleaning) to produce Calcium Aluminate at ALSA GmbH Luenen / Germany, 30 kt/y output capacity


2003 / 2004

construction and commissioning of an Alumina drying facility (feeding system, rotary dryer, bag house filter, screening, packaging) at RAQ Inc. in Becancour/Canada, ard. 20 kt/y output capacity


construction, commissioning and de-bottlencking of an Alumina drying facility (feeding system, rotary dryer, bag house filter, pneumatic conveyors, silo station) at ALSA Sued in Toeging / Germany, ard. 50.000 t/y output capacity

2007 / 2009

start-up, de-bottlenecking and ramping-up of an Alumina drying facility at ALSA GmbH in Hanover/ Germany, ard. 20 kt/y output capacity


  • secondary Alumina for the lines of cement clinker, mineral wool, steel refining slags, refractories, building materials, filler etc.; development of a market of ard. 250 kt/y secondary Alumina in Germany, Europe and North America
  • Feldspar / Quartz products in the ceramic and glass industry;
  • waeltz-slag for the road construction
  • Silicon and SiC, by-products for the metallurgy etc.
  • Mikrosilica for construction
  • mill scale and low grade iron ores for cement kilns etc.
  • ...Hartgesteine als unkonventionelle Feldspatrohstoffe..., (granitic rocks as non-conventional feldspar raw materials), Freiberger Fo.-hefte C399, 1984, S. 49-56
  • Aufschlussverfahren von Bastnäsitkonzentraten, (chemical processing technique of Bastnaesite ore concentrates) Patent DD 262845 A1, 31.07.1987
    Pat REE DD
  • A processing technology for heavily weathered rare earth ores ...,17th Int. Mineral Processing Congr., Dresden, 23-28 Sept. 1991, Preprints Vol. IV, pp. 321-330,
    (dito in: Erzmetall 9/91, pp 452-457),
    DP IMPC 91
  • Geologische Situation und Aufbereitungsmöglichkeiten des Seltene Erden Erzes von Donp Pao/ Vietnam. (geology and processing of the rare earths ore of Dong Pao/Vietnam) - Erzmetall, 44(9/91): 452-457, Weinheim.
    REE DP Erzmetall91
  • Geologische Situation und Aufbereitungsmöglichkeiten des Seltene Erden Erzes von Donp Pao/ Vietnam. (geology and processing of the rare earths ore of Dong Pao/Vietnam) - Erzmetall, 44(9/91): 452-457, Weinheim.
    REE DP NatRes
  • Herstellung v. Schmelzspinell …, (manufacturing of molten spinel ...), Patent DE 433 30 21, 29.09.93
  • Bodenauskleidung f. Elektrolysezellen, (bottom lining of aluminium electrolysis cells), Patent DE 197 22 788 A1, 30.05.97
  • High-Alumina Secondary Raw Materials…, Tile & Brick International, Vol. 14, No. 3, 1998, S. 2-4
  • Hochtonerdehaltiges Pulver, Verfahren zur Herstellung und ..., (high alumina powder, procedure for its production and ...), Patent DE 100 40 582 A1, 15.08.00
  • ... Tonerderohstoff aus der Aufarbeitung von Al-Salzschlacke, (... alumina raw materials from the reclamation of aluminium salt slag), Freiberger Fo.-hefte A 864, 2001, S. 107 ff.
  • Porosierender, erstarrungsbeschleunigter Bindemittelbaustoff-Zusatz und Verfahren zu seiner Herstellung, (porosifying and solidification-accelerating additive for binding agent building materials and procedure of producing), 15.08.2000, Patent EP 1180504, US 6593262, etc.
  • Hochtonerdehaltiger Rohstoff, Verfahren zur Herstellung und …, (high alumina raw material, procedure of producing and ...), Patent EP 144 09 37 B1, 08.01.2004,
  • GET a KIS, Congress of metallurgists (COM) Vancouver, paper 19.3., Aug. 2003,
  • Sustainable reclamation of aluminium salt slags, Vortrag auf dem “Int. Seminar of Al-recycling of ALBA”, Sao Paolo, Okt. 2003,
    Sao Paolo
  • Verfahren zur Herstellung eines halogenarmen hochtonerdehaltigen Rohstoffs, (procedure for producing a low halogen high alumina raw material), Patent DE 102006060209 B3, 18.12.2006
  • An unconventional Al2O3 alternative, Industrial Minerals, Dez. 2006, S. 67-71
  • IM
  • ALSA are developing secondary aluminas, Vortrag auf: 13th bauxite and alumina seminar Athens 06 - 07.03. 2007
  • News from ALSA’s secondary alumninas, paper of the 14th bauxite and alumina seminar Miami, March 2008
  • Hochtonerdehaltiger Rohstoff und Verfahren zur Herstellung, (high alumina raw material and procedure for its production), Patentanmeldung EP 08005328.3, 20.03.08
  • About the processing of carbonatite rare earth ores; paper of the conference on processing and recycling at UVR-FIA Freiberg, Nov. 2012

    REE 2012

  • News release of the company Commerce Resource Corp. about the beneficiation of the Ashram REE ore, Feb. 2013 on
    CRC NR
  • About the reclamation of salt slag / salt cake / black dross (and the recycling of aluminium generally), paper of the conference on processing and recycling, UVR-FIA Freiberg, Nov 2013,
    the salt slag reclamation paper
  • News Release of the Commerce Ressource Corp. web site ( about the beneficiation of the Ashram REE ore, Dec 2013
    CRC NR dez 2013
  • Use of virtual fractions for the MLA of low grade Y-bearing REE ores, paper 894 of IMPC 2016 Quebec,
    894 IMPC Y-ores
  • Virtuelle Fraktionierung bei der MLA armer Y-REE-Erze. Bergbau 5/2017, 217ff
    Bergbau 5/2017
  • News release of CRC ( about publication of flotation results on Ashram ore (flotation of REE-minerals from fluorite by pH-shift) with Flotation17,
    CRC NR 1712
  • Flotation of REE-minerals from Fluorite by pH-shift; poster presentation of the “Flotation 17” conference, Capetown Nov 2017., REE-flot pH-shift_Flot17mmp
  • Rare earths – Aspects of Market and Beneficiation, World of Metallurgy – Erzmetall 71 (2018) No. 4, pp 189ff, REE aspects_mmp erzmetall 418
  • PARISITE FLOTATION FROM CARBONATITE REE-ORE, Flotation 19, Oral presentation MEI-conference Capetown Nov 2019., mmp_Parisite-flotation, MEI19