Cement Kilns: Difference between revisions

Revision as of 19:13, 7 April 2020

The production of cement utilizes waste materials in two primary ways, firstly using specific Industrial Waste and Mining & Quarrying Waste (and waste from the kiln part of the process itself) as additives and replacement for traditional raw materials, and secondly as a fuel to substitute for the use of traditional fossil fuels in a cement kiln. In 2018 1,414,195 tonnes of waste was used as raw materials and fuel in the production of cement, with just over 43% of kiln thermal input replaced by Waste Derived Fuel. The five companies manufacturing cement together supplied 78% of the cement consumed in the market in 2018. ^[1].

The Process

There are six main stages of cement manufacture^[2]:

Stage 1 - Raw Material Extraction: raw ingredients include limestone, sand and clay, shale, fly ash, mill scale and bauxite. Materials are mined, crushed and reduced in size.
Stage 2 - Grinding, Proportioning and Blending: the production of a fine homogeneous mix with additives that comprises primarily around 80% limestone and 20% clay.
Stage 3 - Pre-heating Raw Material: a pre-heating chamber using kiln 'exhaust' gases to reduce energy consumption and pre-condition the raw material into oxides.
Stage 4 - Kiln Phase: the principle phase which produces a clinker, exiting the kiln in marble-sized nodules - it is the binder that is use din cement products.
Stage 5 - Cooling and Final Grinding: the clinker is rapidly air-cooled and gypsum (and other active ingredients as required) is added to the clinker and ground to a fine power to produce cement
Stage 6 - Packing and Shipping: the cement is conveyed from grinding mills to silos where it is then packed in bags.

The introduction of waste materials - or 'Alternative Raw Materials' as coined by the industry - can be as part of the kiln phase or the final grinding stage and the percentage of recycled content of cement was almost 10% across these in 2018.

Not all cement kilns have have the total 'end to end' process on site, with some sites producing the clinker for subsequent grinding, blending and packing at a different site. This might include, for example, the introduction of other materials, such as Blast Furnace Slag to produce a Blast Furnace Cement - a highly sulphate resistant cement that can have up to 65% granulated Blast Furnace Slag mixed with the clinker. As Blast Furnace Slag is considered a primary input for this type of cement, it is not defined as waste and therefore is not normally captured in UK Waste Tonnage.

List of Cement Kilns

More detailed information can be found by clicking through to the site-specific page:

ID	Site Name	Operating Company
1.	Aberthaw Cement Kiln	Tarmac
2.	Cauldon Cement Kiln	Aggregate Industries t/a Lafarge Cement
3.	Cookstown Cement Kiln	Aggregate Industries t/a Lafarge Cement
4.	Tarmac Ltd, Dunbar Plant	Tarmac
5.	Hope Cement Kiln	Breedon Cement
6.	Ketton Cement Kiln	Hanson Cement
7.	Padeswood Cement Kiln	Hanson Cement
8.	Ribblesdale Cement Kiln	Hanson Cement
9.	Rugby Cement Kiln	Cemex
10.	South Ferriby Cement Kiln	Cemex
11.	Tunstead Cement Kiln	Tarmac
12.	Purfleet Cement Kiln	Kerneos
13.	Tilbury Cement and Ash Plant	Cemex
14.	Dagenham Cement Depot	Breedon Cement
15.	Dewsbury Cement Depot	Breedon Cement
16.	Reading (Theale) Cement Depot & Concrete Plant	Breedon Cement
17.	Walsall Cement & Aggregates Depot	Breedon Cement
18.	Barnstone Cement Plant	Tarmac
19.	Celtic Ash	Tarmac
20.	Tarmac Northfleet Works	Tarmac
21.	Seaham Depot	Tarmac
22.	ScotAsh	Tarmac
23.	Tarmac Thurrock Wharf	Tarmac

List of Grinding and Blending Sites

Site	Company	Process
Tilbury	Cemex	Grinding and Blending
Dagenham	Breeden	Blending only
Dewsbury	Breeden	Blending only
Theale	Breeden	Blending only
Walsall	Breedon	Blending only
Barnstone	Tarmac	Grinding only
Celtic Ash	Tarmac	Blending only
Northfleet	Tarmac	Blending only
Seaham	Tarmac	Blending only
Scotash	Tarmac	Blending only
West Thorrock	Tarmac	Blending only

^[3].

References

[1] MPA Cement Sustainability report 2019

[2] ttps://civiltoday.com/civil-engineering-materials/cement/106-cement-manufacturing-process

[3] MPA Cement Sustainability report 2019

[1]

[2]

[3]

@@ Line 11: / Line 11: @@
 * Stage 6 - '''Packing and Shipping''': the cement is conveyed from grinding mills to silos where it is then packed in bags.
-The introduction of waste materials - or 'Alternative Raw Materials' as coined by the industry - can be as part of the kiln phase (or Kiln Feed stage) or the final grinding stage (or Interground stage) and the percentage of recycled content of cement in 2018 is summarized in the following graphic and was almost 10% <ref>[https://cement.mineralproducts.org/documents/MPA_Cement_SD_Report_2019.pdf MPA Cement Sustainability report 2019]</ref>:see diagram below:
+The introduction of waste materials - or 'Alternative Raw Materials' as coined by the industry - can be as part of the kiln phase or the final grinding stage and the percentage of recycled content of cement was almost 10% across these in 2018.
-[[File:Cement recycled content graphic.png|400px|left|Figure 2 from MPA Cement Sustainability Report, 2019]]
-<br clear='left'/>
 Not all cement kilns have have the total 'end to end' process on site, with some sites producing the clinker for subsequent grinding, blending and packing at a different site. This might include, for example, the introduction of other materials, such as Blast Furnace Slag to produce a Blast Furnace Cement - a highly sulphate resistant cement that can have up to 65% granulated Blast Furnace Slag mixed with the clinker. As Blast Furnace Slag is considered a primary input for this type of cement, it is not defined as waste and therefore is not normally captured in [[UK Waste Tonnage]].