Herzog Nonferrous

Aluminum metal is produced from alumina by electrolytic reduction. Using the Hall- Héroult process, alumina is decomposed in a cryolite electrolyte at about 1230 K. The conditions of the electrolytic cell has to be monitored carefully as slight changes in composition lead to significant alterations of the whole process. The addition of calcium fluoride and aluminum fluoride decreases solubility of alumina while lowering the melting point. Too low alumina concentrations my cause the so-called anode effect resulting in very high resistance to the flow of current at the anode surface. Too high alumina concentrations may lead to sludge formation. Lithium fluoride and sodium are affecting the efficiency by altering the conductivity of the bath.

In the Hall- Héroult process, the oxygen is separated from the alumina and combine with carbon from the carbon anode. The remaining molten aluminum accumulates at the bottom of the pot and is siphoned out.

In the Hall- Héroult process, the oxygen is separated from the alumina and combine with carbon from the carbon anode. The remaining molten aluminum accumulates at the bottom of the pot and is siphoned out. From the holding furnace, the molten aluminum is cast into an ingot. At that point, solid metallic samples are taken for optical emission spectroscopy. Sample shapes used for quality control vary from laboratory to laboratory. Some of the sample shapes have to undergo sawing before milling. The HN-FF or HN-SF can operate most of the sample shapes without major adaptation of the machine or sample handling.

Depending on the quality of the scrap, electrorefining is necessary. In primary smelters, copper scrap is largely applied as a coolant in ore-based copper production. In the matte-converting process, impure scrap is used for the slag-making stage whereas pure copper is used for the copper-making stage. Cooper scrap can be smelted in a number of different furnaces including blast furnaces, reverberatory, rotary, bath smelting or electrical furnaces.
In addition, electronic scrap (WEEE) enters the copper recycling process. The copper content in electronic scrap may vary between 3 and 27%. The electronic scrap is usually smelted under reducing conditions resulting in so-called black copper, which is further processed under oxidizing atmosphere to remove impurities.
The major challenge for sample preparation in the copper mining and recycling industry is the wide range of element concentrations and varying material properties of the various QC samples. One important focus of sample preparation is therefore to avoid cross-contamination between subsequent samples.
Samples originating during the copper production process include geological samples, leach feeds/ residues, concentrates, slags, matte, anodes, cathodes, ashes, environmental samples, and many more.  Quality control involves many different and complex analyzing methods including XRF, quantitative XRD, ICP, OES, AA, combustion analysis, fire assay, and other more. HERZOG equipment covers all relevant preparation steps including moisture determination, filtration and drying, crushing, pulverizing, pelletizing, fusion, screening, blending/splitting, and bagging.

Nowadays, 80% of lead is used in lead-acid batteries. At the same time, recycling rates of lead are between 56% and 73%, which is one of the highest rates of all materials in common use today. Primary lead is produced from ore containing galena (PbS). The ores are concentrated, fine-ground and subsequently undergo a process called “sintering” which includes oxidation of the galena and fusion to larger lumps. Afterwards, sintered lumps and coke are loaded into a blast furnace where lead bullions are produced.  Especially primary bullions need further metallurgical and electrometallurgical refining including decopperisation, oxidation of Sn, Sb and As, precious metal refining, and Bi removal.

There is a variety of samples used for the quality control of the production process. These include lead, lead alloys, lead ash, lead dust, lead sulfates, slag, sludge, and many more. Sample preparation of these raw materials encloses sampling, drying, moisture determination, grain sizing, splitting, and pulverizing. Potential health hazards of some of these substances support the trend towards automation of these processes. Lead is a very soft metal having a tendency to stick on surfaces. Therefore, thorough cleaning processes may be necessary to avoid contamination of subsequent samples.
Solid lead samples obtained in the smelting and refining process are usually milled using special non-ferrous milling machines. The sample is analyzed be optical emission spectroscopy. Potential residues in the sample preparation machine and the spark stand may require specific cleaning mechanisms.

Magnesium is produced using the silicothermic Pidgeon process, the Dow process, or the solid oxide membrane technology. Magnesium is a frequently used structural metal, taking third place behind iron and aluminum. Lightweight structural magnesium alloys are used in critical aerospace, automotive and military applications, including jet engine transmissions, generator housings, power-takeoff systems and other type of equipment running at high temperatures.
Magnesium and magnesium alloys are explosive and highly flammable. Therefore, sample preparation requires special precaution measures. Using the milling machines HN-FF, we offer special configuration of the milling chamber for complete chip removal without residues.