How COSMA on Your Finish Mill Can Improve Your
Plant's Performance
Cement Analysis


COSMA - Technical Differentiation
Mineralogical knowledge is vital in the determination of the performance of a cement plant and the cement product itself. However, mineralogical information is generally only estimated from chemical analysis in the laboratory. While it has generally not been practical to gather large amounts of mineralogical information before now, the fact that serious attempts are being made by cement manufacturers to estimate mineralogy from Bogue equations indicates the importance placed on it by those who understand the process. Unfortunately, these estimates are often incorrect and are therefore misleading.

COSMA measures information on mineralogy directly, continuously and in real time. COSMA provides to plant operators the key information they need to understand, optimise and control the manufacturing process. The value that this will create is difficult to estimate, but could potentially be of great significance.

COSMA - Benefits of a Cement Installation

A number of COSMA machines are already in service analysing cement mill product. The benefits realised from these installations fall into the following categories.

  1. Quality control
    COSMA allows better and more consistent control of quality parameters, as it provides accurate analysis of free lime, alite, belite, and other mineral phases, as well as the gypsum hydration states in real time. One example is the control of gypsum de-hydration with mill water sprays. Gypsum de-hydration plays a crucial role in cement setting times, which is an area of concern in many plants. COSMA also provides total sulphate in cement, allowing control of gypsum weighfeeders based on SO3 content.

    Cement analysis gypsum states

  2. Fine control of limestone/kiln dust/fly ash/pozzolans replacement
    Typically, the amount of filler material added by a plant is significantly lower than that allowed by Quality Standards in order to ensure that maximum permitted levels are not exceeded. By knowing the exact content of a particular filler material at all times, the plant can increase targets without any risk of exceeding them, thereby allowing the plant to increase its use of low cost filler material in cement.

    Following is an estimate of the cost/benefit for 1,000,000tpa cement plant with clinker cost per tonne of $28 and limestone cost per tonne of $8, and with a limestone addition limit of 5%. Cement price is $50 per tonne. Assume that limestone addition can be increased from 3% to 4.5% through closer control of the finish mill with COSMA.

    Clinker savings
    Cost difference clinker & limestone = $20/tonne
    Limestone substitution savings @ 3% = 1,000,000tpa x 3% x $20/tonne
      = $600,000
    Limestone substitution savings @ 4.5%
    = 1,000,000tpa x 4.5% x $20/tonne
      = $900,000
    Increased annual savings via COSMA = $300,000

    Production increase

    Current annual plant revenue = 1,000,000tpa x $50/tonne = $50,000,000
    Annual production increase @ 1.5% = 15,000 tonnes
    Annual revenue increase @ $50 = $750,000
    Annual profit increase = $750,000 – (15,000 x $28) = $330,000

    Limestone Addition

  3. Plant optimisation
    COSMA provides information about the plant and the cement product that has not previously been available. This information gives the operators insight into mill performance, and enables the plant to optimise both materials and plant operation. For example, the understanding of the correlation between mineralogy and product performance will enable the plant to optimise raw mix design to produce optimal product performance with the minimum production costs.

    Cement Analysis

  4. Reduction in fringe material
    A plant that produces a number of different cement types sends changeover material to Fringe Bins for reblending. COSMA gives plant operators the information they require to identify the exact point at which the material reaches the required specification. Thus, changeover fringe material is minimised.