Calcium carbonate slurries

Both natural ground or precipitated calcium carbonate are available as dry products shipped in 22.7 kg multiwaH bags, supersacks, or in bulk via tmck and railcar. Calcium carbonate slurry, primarily used by the paper industry, is shipped by tmck and rail. The soflds content of these slurries is typically >70% by weight for ground products and 20—50% for precipitated. In the 1980s small precipitation plants were built at the site of large North American papermills. 

New Polymeric Dispersants for Very Fine Calcium Carbonate Slurries... 

These specific requirements of a calcium carbonate slurry used for paper coating have necessitated the development of new dispersants that allow the preparation of ultra fine calcium carbonate slurries at high solids concentration that provide good rheological behaviour in coating. 

This article studies some of the polymer characteristics influencing the slurry dispersion and describes a new class of acrylic based polymer showing promising dispersing properties for ultra fine calcium carbonate slurries. 

We developed another dispersant presenting properties for a special application. In some cases when an ultra fine calcium carbonate slurry is spray dried, a re-agglomeration of the powder often occurs, due to high water adsorption. This powder aggregation is detrimental to the quality of the final product. 

In this section we give a description of the colloidal interactions which govern the state of dispersion and rheology of calcium carbonate slurries. The description is based on a series of fundamental experimental studies that have been described in more detail in previous publications. ... 

From the preceding discussion, the most obvious way to improve the performance of polyacrylate-dispersed calcium carbonate slurries is to reduce the solution ionic strength by reducing the amount of non-adsorbed polymer in solution. 

Measures taken to minimise the amount of unadsorbed polymer in solution have been shown to improve the viscosity performance of both kaolin and calcium carbonate slurries. These include adjustment of the pH or initial neutralisation of the polymer to increase its affinity to the surface and fractionation of the polymer to reduce the width of its molecular weight distribution. 

A sample of a standard calcium carbonate slurry was received from a large manufacturer in the USA. This sample was subjected to preservative efficacy testing according to the ASTM E 723-91 test protocol. Preservative treated samples were inoculated with a mixed bacterial inoculum containing organisms with a known tolerance or resistance to BIT (l,2-Benzisothiazolin-3-one). Untreated controls were included for reference purposes. The test procedure is outlined below. 

Figure 1 Preservative ejficacy of BIT in a calcium carbonate slurry using the ASTM E723-91 test procedure...

These results point to the potential for Bronopol as a preservative in calcium carbonate slurries. In addition, they also indicate the ability of Bronopol to act as a clean-up treatment in slurries already contaminated with organisms showing tolerance or resistance to other preservatives. 

Data taken from the plate and frame filter press located in the unit operations laboratory are used to determine a, the specific cake resistance, of a calcium carbonate slurry. Several values of a, expressed in ft/lb, have been calculated from data taken during the fall semester. 

A rotary-drum filter filters 20 m /h (706 ft /h) of a calcium carbonate slurry at 20 °C (68 °F). The pressure drop across the cake is 0.658 bar (9.541 psi). If the slimy contains 0.15 mass fraction of calcium carbonate, and the filter cake contains 0.40 mass fraction of water, estimate the surface area of the rotary-drum filter. 

Renko, E. K. (1998). Modelling hindered batch settling part II A model for compnting solids profile of calcium carbonate slurry. Water S.A. 24, 4, 331-336. 

The most common absorbents are lime (calcium hydroxide) and limestone (calcium carbonate) slurries. Limestone is the preferred absorbent in many modern scrubbers, because of its low cost compared with lime and other absorbents.However, lime is also used because of its higher reactivity, which allows it to absorb sulfur more rapidly. This makes it possible to use smaller scrubbers to treat a given quantity of gas when lime is the absorbent. When lime or limestone... 

Chem. Descrip. Calcium carbonate slurry CAS 471-34-1 EINECS/ELINCS 207-439-9 Uses Filler for aq. coatings and inks, paper, paper coatings, thermosets (glass-reinforced polyester), thermoplastics (PP, ABS), PVC pipe, siding, profiles, extrusion, film, sheeting, color cones., paints (gloss, semigloss, flat latex)... 

Chem. Descrip. Precipitated calcium carbonate slurry CAS 471-34-1 EINECS/ELINCS 207-439-9 Uses Coating pigment for glossy, high brightness coated paper and board applies. 

Figure 6.2 The eflFect of organic acid carbon chain length on the viscosity of calcium carbonate slurries in squalane (a model hydrocarbon fluid) measured at different frequencies. (Reproduced with permission from Ref [7].)...

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