Raw & Waste materials

Raw and waste materials

Sommario

• Raw and waste materials ........................................................................................................................... 1
• 1. Intro RWM ................................................................................................................................................. 2
• 1.1 Definition ........................................................................................................................................... 2
• 2. RWME natural stones ................................................................................................................................ 2
• 3. Decay treatment of natural stones ........................................................................................................... 4
• 3.1 Ageing tests ....................................................................................................................................... 5
• 3.2 Different kind of cutting .................................................................................................................... 7
• 3.3 Surface finishing treatment ............................................................................................................... 7
• 4. Aggregates ................................................................................................................................................. 7
• 4.1 Aggregates characterization .............................................................................................................. 8
• 4.2 Treatment of aggregates ................................................................................................................... 9
• 5. Physical properties for mineral processing ............................................................................................... 9
• 5.1 Density ............................................................................................................................................. 10
• 5.2 Magnetic susceptibility .................................................................................................................... 10
• 5.3 Electrical conductivity ...................................................................................................................... 11
• 5.4 Yield and recovery ........................................................................................................................... 11
• 5.5 Sampling .......................................................................................................................................... 12
• 7. Screening and comminution .................................................................................................................... 12
• 7.1 Comminution ................................................................................................................................... 13
• 7.2 Milling .............................................................................................................................................. 15
• 8. Magnetic separators ................................................................................................................................ 18
• Equipments .................................................................................................................................................. 19
• Classification in a fluid (air or water) ........................................................................................................... 21
• 9. Separations .............................................................................................................................................. 22
• 1 10. Waste regulations and critical raw materials ...................................................................................... 25

1. Intro RWM

1.1 Definition

Ore (giacimento) = mineral raw material in solid state (composed by rock)

Crude oil = energetic mineral raw material in liquid state

Primary raw materials (PRM/RM) = solid georesources with commercial value intended for use in industry

Secondary raw materials (SRM) = solid material derived from the recovery and recycling of waste

Raw materials = they get through an activity that can be defined by mining, followed by the activity defined treatment. The final raw product will go to the manufacturing industry

Waste raw materials = they get through an activity that can be defined urban mining followed by the activity defined by treatment. The final raw product will go the manufacturing industry

Georesources = are represented by the set of the geological concentration of useful materials present in the earth’s crust

Mineral processing (mineral preparation, solid treatment, ore dressing, ore beneficiation, mineral dressing, milling represents all the operations needed to transform the “as mine” ore into the commercial product

2. RWME natural stones

Construction products may only be placed on the market if they are suitable for the intended use and have to follow this essential requirements:

• Mechanical strength and stability
• Safety in case of fire
• Hygiene, health and the environment
• Safety in use
• Noise protection
• Energy saving and heat retention

All construction products, if suitable for the intended use, must be marked with the CE marking, accompanied by a certificate of conformity to the European Regulation of construction products.

CE marking is a paper/identification of a product and it is related to the safety of this product. It is consulted in order to use a specific material for a specific purpose (paving, roof). It is important because the producer has to prepare the CE marking for each of it product. The producer has to perform different tests in order to determine the safety of the product.

2

Apparent density = depends from the presence of pores and therefore it is linked to its mineralogic composition and to its structure

Natural stone test methods – determination of real density and apparent density

The most precise method is that of the hydrostatic balance based on the Archimedes principle (each body immersed in water is subjected to an upward buoyant force equal to the weight of the displaced water volume) →

In order to determine the real density the volume of the solid part of a rock is measured by grinding the sample until a powder with a particle size of less than 0.1 mm is obtained. The weighted average of the voluminous masses of the minerals present in the rock is equal to its real density. Real density is expressed by the ratio between the milled and dried specimen and the volume of the liquid moved from the mass.

Porosity

It indicated the volume of voids in the specimen relative to its apparent volume in percentage. We need the saturated mass, the weight in water and the unsaturated mass. Water absorption is the amount of water that can enter in the specimen (percentage in mass)

Thermal expansion

It is important to leave to the rock the possibility to expand. First measurement of the length on the previously dried specimen, taken when it is returned to the ambient temperature. Second measurement at least 30 min after the specimen has reached the temperature of 80 degree. At least 2 cycles are performed. The cooling of the specimen up to room T must occur naturally.

Compressional strength

Resistance that bodies oppose to forces that tend to break them by crushing. The result of the compression test depends on the shape, size of specimen, regularity of form, load application speed. It is expressed by the ratio between the agent force and the area of the section on which the force P is applied. The force acting must be uniformly distributed on equal and opposite faces of the specimen and their result pass through the centre of gravity.

Flexural strength

Prismatic specimens are subjected to compression in the upper face and to tensile force in the lower face. On the upper rollers is applied a force, the ones down are fixed.