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Physical & Chemical properties

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Solution obtained from the treatment (scrubbing and cooling) of the SO2 containing gasses from copper production processes. The solution can be used to produce gypsum or as a leaching agent, or can be thermally decomposed. It consists mainly of sulphuric acid and copper sulphate, and may contain other non-ferrous metal compounds.Synonyms are weak acid, dilute acid or bleed.

The UVCB substance, which is a complex mixture of metallic salts and sulphuric acid, which decomposes and partially precipitates spontaneously at ambient temperature. The major constituents of the UVCB are Sulphuric acid (with ca. 20%) and water (ca. 78%). In a representative sample, the main residual constituents was As (0,57%), Si (0,05%), Na (0,03%), iron (0,01%), and Zn (0,02%).

Water solubility of the UVCB can be read-across from its major constituent Sulphuric acid (which is miscible in water). The behaviour of the other constituents of the substance can be derived from solubility of the respective sulphate salts (eg copper sulphate, iron sulphate, aluminium sulphate, etc), when totally dissolved in the UVCB.

At room temperature, the substance is a liquid.

The UVCB can be considered as containing mainly contain sulfuric acid (ca 20 to 30% w/w) and water. A detailed chemical analysis (ICP) was performed on a representative sample (IUCLID 4.23).

The majority of the available data on physical and chemical properties of the UVCB is therefore read across from sulphuric acid data (as found in publicly available literature and reviews). Additional testing were performed on a representative sample in view to address boiling temperature, vapour pressure and self ignition properties, etc of the material ( REACH Copper Consortium).

It is important to note that the UVCB is not stable, and precipitates may be formed during transport.  

Explosive properties can be excluded in the absence of structural alerts. Flammability testing in accordance with UN Transport Test N1 is not applicable to a liquid. Experience of handling and use provide sufficient information to indicate the substance is not pyrophoric and investigation in accordance with UN Transport Test N3 is not required. The UVCB is not considered for oxidizing properties according to CLP -it is therefore not necessary to consider it for classification as self-reactive substance. From sulphuric acid, it is known that the substance emit flammable gases when in contact with metals. In addition the substance reacts with water, emitting SO2 (non-flammable gas).

 

The selection and collection of the representative samples was made based on expert knowledge and according to a standardized sampling protocol developed by the REACH Copper Consortium, an industry joint-venture regrouping major manufacturing and importing companies of the UVCB substance. Details on the sampling approach and the representative samples are reported as supporting information in IUCLID 1.4 and 4.1.

 

Sulphuric acid is known to be a strong mineral acid that has a high affinity for (and is miscible with) water. It dissociates in water to form sulphate and hydrogen (carbonium) ions. The dissolution and dissociation of sulphuric acid in water is strongly exothermic and occurs with a vigorous reaction. Sulphuric acid is known not to have oxidizing properties according to CLP (cellulose test).

These properties do also apply to the UVCB, to a minor extent (due to lower content in H2SO4) and with the consequence that the high affinity to water induce more or less precipitation of non-ferrous metal salts to occur.

Table 1: Summary of the results

ECI Comments / Remarks IUCLID Section Weak acid, dilute acid, bleed
Lab code   09TT03914
State / Colour 4.1 Liquid, transparent/cloudy
Relative Density g/m3 4.4 1.14
Specific surface area 4.5 n.d.
Granulometry, D50, µm 4.5 n.d.
Water solubility 4.8 high, for sulphuric acid portion of the UVCB
Freezing/pouring , ºCBoiling temperature,°C 4.24.3 258384
Vapour pressure, hPa 4.15 2.3
Assays / Chemistry 4.23 See table and text above
sulphuric acid + soluble salts from non-ferrous metals
Flammability 4.13 may react strongly with water; no pyrophicity
Self-ignition  4.12 above 400ºC
Explosive properties 4.14 negative
Oxidizing properties 4.15 negative

Corrosive to metals positive (H2SO4)