Triangular formula

Paper recycling

There are three categories of paper that can be used as feed stocks for making recycled paper mill broke, pre-consumer waste, and post-consumer waste.

 Mill broke is paper trimmings and other paper scrap from the manufacture of paper, and is recycled internally in a paper mill.

 Pre-consumer waste is material which left the paper mill but was discarded before it was ready for consumer use.

 Post-consumer waste is material discarded after consumer use, such as old corrugated containers  old magazines, and newspapers.Paper suitable for recycling is called "scrap paper", often used to produce molded pulp package

paper recycling process:

The process of waste paper recycling involves mixing used paper with water and chemicals to break it down. It is then chopped up and heated, which breaks it down further into strands of cellulose, a type of organic plant material; this resulting mixture is called pulp, or slurry. It is strained through screens, which remove any glue or plastic that may still be in the mixture then cleaned, de-inked, bleached, and mixed with water. Then it can be made into new recycled paper.

Recycling Basics:

Recycling:is the process of collecting and processing materials that would otherwise be thrown away as trash and turning them into new products. Recycling can benefit your community and the environment.

Benefits of Recycling

• Reduces the amount of waste sent to landfills and incinerators;
• Conserves natural resources such as timber, water, and minerals;
• Prevents pollution by reducing the need to collect new raw materials;
• Saves energy;
• Reduces greenhouse gas emissions that contribute to global climate change;
• Helps sustain the environment for future generations;
• Helps create new well-paying jobs in the recycling and manufacturing industries

Steps to Recycling Materials

Recycling includes the three steps below, which create a continuous loop, represented by the familiar recycling symbol.

• Step 1: Collection and Processing
  There are several methods for collecting recyclables, including curbside collection, drop-off centers, and deposit or refund programs. 

  After collection, recyclables are sent to a recovery facility to be sorted, cleaned, and processed into materials that can be used in manufacturing. Recyclables are bought and sold just like raw materials would be, and prices go up and down depending on supply and demand in the United States and the world.
• Step 2: Manufacturing
• More and more of today's products are being manufactured with recycled content. Common household items that contain recycled materials include:
  • newspapers and paper towels;
  • aluminum, plastic, and glass soft drink containers;
  • steel cans; and
  • plastic laundry detergent bottles.
  Recycled materials are also used in new ways such as recovered glass in asphalt to pave roads or recovered plastic in carpeting and park benches.

Industrial waste

Waste which is thown out as an un wanted material ruselt inch in effecting econmny of the country plus increasing pollution

Experimentation.

Experimenting different cold binders

Grinding of sanitary waste

other binders

Lime

There are two forms of lime: quicklime and hydrated lime.

Quicklime is produced by heating rock or stone containing calcium carbonate (limestone, marble, chalk, shells, etc.) to a temperature of around 1000°C for several hours in a process known as 'calcining' or sometimes simply 'burning'. It is an unstable and slightly hazardous product and therefore is normally 'hydrated' or 'slaked', by adding water, becoming not only more stable but also easier and safer to handle.

To produce dry powdered hydrated lime just sufficient water is added for the quicklime lumps to break down to a fine powder. This material would have a 'shelf life' of only a number of weeks, depending on storage conditions. 'Old' hydrated lime would have partially carbonated and become a less effective binder.

However, if quicklime is hydrated with a large excess of water and well agitated, it forms a milky suspension known as milk of lime. Allowing the solids to settle, and drawing off the excess water, forms a paste-like residue, termed lime putty, which is the form of lime which can be used in building applications to best effect. This will keep almost indefinitely and, in fact, improves with age. In most countries, though, lime is most widely available as a powder, due to its widespread utilisation in process and treatment industries rather than in construction. Lime putty, which needs a stiff bag or container for transportation, is more rarely produced.

Limes with high calcium content, often called 'fat' or 'white' limes are desirable for most industries, although the construction industry can use limes containing impurities. For instance, limestones containing a proportion of clay are often seen as an advantage in building as they produce hydraulic limes which will set under water and will produce stronger mortars.

In the construction industry, lime, in its hydrated or putty form, is mixed with aggregate and water to produce concrete or mortar in the usual manner. Lime putties generally produce mortars and renders of excellent quality and consistency.

Plain lime-sand mortars are quite weak; any early adhesive strength results from drying out, and longer term hardening occurs through the action of the air's carbon dioxide on the lime.

Traditionally lime renders and plasters were often mixed with animal hair to improve cohesion. Today the addition of gypsum or Portland cement and/or pozzolanas to increase durability and give faster setting times is usual.

Pozzolanas

Pozzolanas are materials which, although not cementitious in themselves, will combine chemically with lime in the presence of water to form a strong cementing material. They include:

• Volcanic ash
• Power station fly ash (usually known as pfa)
• Burnt clays
• Ash from some burnt plant materials
• Silicious earths (such as diatomite)

Materials not already in a fine powdered form must be ground, and some require calcining at around 600 -750 °C to optimize their pozzolanic properties.

Pozzolanas can be mixed with lime and/or Portland cement and can improve quality and reduce costs of concretes made from both materials.

In some countries (e.g. India and Kenya), pozzolanas are mixed with Portland cement and sold as blended cement, which in many respects is similar to Portland cement. In other countries (e.g. Cuba) lime/pozzolana/Portland cement blends are sold as an alternative to Portland cement. Lime-pozzolana cement by itself can make an excellent cementing material for low-rise construction or mass concrete and in some countries (e.g. Indonesia) is still produced extensively.

Gypsum plaster

Gypsum is a not an uncommon mineral, and needs only a low temperature, of around 150°C, to convert it into a very useful binding material, known as hemi-hydrate or plaster of Paris.

On its own, plaster of Paris sets very rapidly when mixed with water. To give time for it to be applied, around 5% of lime and 0.8% of a retarding material (such as the keratin glue-like extracts from boiling fish bones or animal hoof and horn) are added to the plaster.

Retarded plaster of Paris can be used on its own or mixed with up to three parts of clean, sharp sand. Hydrated lime can be added to increase its strength and water resistance. Gypsum plasters can be reinforced with various fibrous materials from reeds to chopped glass fibres.

Gypsum plaster is not wholly resistant to moist conditions and so is normally used internally, except in the drier Mediterranean and Middle Eastern countries where it has traditionally been used as an external render.